BEE Exam Prep › Paper-1 › Chapter 4

BEE Paper-1 — Chapter 4: Energy Management & Audit

153 questions — 65 objective (1 mark), 72 short (5 marks), 16 long (10 marks). Every answer is checked against the 2014 BEE guidebook and carries its book section reference plus an explanation.
▶ Practice this chapter interactively (timer, read-aloud, progress saving).

Objective questions (1 mark) — 65

📖 §4.12 Energy audit instruments — Ultrasonic Flow Meter

1. Non-contact flow measurement can be carried out by ____.

  1. Orifice meter
  2. Turbine flow meter
  3. Ultrasonic flow meter
  4. Magnetic flow meter
Answer: C) Ultrasonic flow meter
Confirmed vs Book-1 §4.12 — Book §4.12: the ultrasonic flow meter is "one of the popular means of non-contact flow measurement" (transit-time or Doppler), clamped on the outside of the pipe. Orifice and turbine meters are intrusive/in-line devices inserted in the fluid stream, and a magnetic flow meter, though obstruction-less, is still a wetted in-line spool piece — so only the ultrasonic meter is non-contact.
Source: Sep 2021
📖 §4.9 Maximizing system efficiencies (continuous-improvement practice; term itself not defined in Ch4 text)

2. Which of the following means 'continuous improvement'?

  1. Seiton
  2. Kaizen
  3. Seiso
  4. Kanban
Answer: B) Kaizen
Confirmed vs Book-1 §4.9 — Kaizen is the Japanese term for continuous improvement, i.e. small ongoing improvements in operation and maintenance practice — the spirit of Book §4.9 'best operation and maintenance practices'. Seiton (set in order) and Seiso (shine/clean) are 5-S housekeeping steps, and Kanban is a pull-type production-signalling system, so none of those means continuous improvement.
Source: Sep 2021
📖 §4.12 Energy audit instruments — Speed Measurements

3. Contact type speed measurement can be carried out by ____.

  1. Tachometer
  2. Stroboscope
  3. Oscilloscope
  4. Odometer
Answer: A) Tachometer
Confirmed vs Book-1 §4.12 — Book §4.12: "a simple tachometer is a contact type instrument, which can be used where direct access is possible." The stroboscope is expressly listed as the more sophisticated and safer NON-contact alternative, so it is the tempting wrong answer here; an oscilloscope displays waveforms and an odometer measures distance travelled.
Source: Sep 2021
📖 §4.6 Benchmarking — benchmark parameters

4. Which one is not an energy consumption benchmark parameter?

  1. kcal/kWh of electricity generated
  2. kg/deg C
  3. kWh/kg of fertilizer
  4. kWh/kg of yarn
Answer: B) kg/deg C
Confirmed vs Book-1 §4.6 — Book §4.6 benchmarks always relate energy to output: kcal/kWh (power-plant heat rate), Million kcal or kWh per MT of fertilizer, kWh/kg of yarn. 'kg/deg C' relates mass to temperature and carries no energy term at all, so it cannot be a specific-energy benchmark.
Source: Sep 2021
📖 §4.12 Energy audit instruments — Non Contact Infrared Thermometer

5. Infrared thermometer is commonly used to measure:

  1. Surface temperature
  2. Flue gas temperature
  3. Steam Temperature
  4. Hot water temperature
Answer: A) Surface temperature
Confirmed vs Book-1 §4.12 — Book §4.12: the IR thermometer computes temperature from the thermal radiation emitted by an object's SURFACE, and is used for objects in hazardous or hard-to-reach places. Flue gas, steam and hot-water temperatures are stream temperatures taken by inserting a contact thermometer (thermocouple) probe into the stream, per the Contact Thermometer entry.
Source: Sep 2021
📖 §4.1 Definition and Objectives of Energy Management (Book EOC Objective Q3)

6. The objective of energy management includes

  1. minimising energy costs
  2. minimising waste
  3. mitigating environmental degradation caused by energy
  4. all the above
Answer: D) all the above
Confirmed vs Book-1 §4.1 — Book §4.1 lists three objectives: optimum energy procurement and utilisation, minimising energy costs/waste without affecting production and quality, and minimising environmental effects. Since (a), (b) and (c) are each one of those listed objectives, only 'all the above' is complete.
Source: Apr 2010
📖 §4.12 Energy audit instruments — Fyrite

7. The instrument used to measure CO2 from boiler stack is

  1. infrared thermometer
  2. fyrite
  3. anemometer
  4. pitot tube
Answer: B) fyrite
Confirmed vs Book-1 §4.12 — Book §4.12: in the Fyrite a hand bellows pump draws flue gas into an absorbing solution — potassium hydroxide (dyed red) for CO2, chromous chloride (blue) for O2 — and the liquid-volume change reads the gas percentage. An infrared thermometer reads surface temperature, an anemometer air velocity and a pitot tube duct pressure/velocity, so none of them measures CO2.
Source: Apr 2010
📖 §4.11 Fuel and Energy Substitution

8. Replacement of steam based hot water generation by solar water heating system is an example of

  1. matching energy usage to the requirement
  2. maximising system efficiency
  3. energy substitution
  4. performance improvement
Answer: C) energy substitution
Confirmed vs Book-1 §4.11 — Book §4.11 gives exactly this example under 'few examples of energy substitution': "Replacement of steam based hot water by solar systems." It is not matching usage to requirement (§4.8, e.g. impeller trimming) nor maximising system efficiency (§4.9, e.g. steam traps) — the energy SOURCE itself is changed.
Source: Apr 2010
📖 §4.4 Step 6 Analysis of energy use / energy balance (Sankey detail in Book-1 Ch5 & Ch9)

9. Which among the following statements is not applicable in the case of Sankey diagram?

  1. useful tool to represent entire input and output energy flow
  2. represents visually, various outputs and losses
  3. depicts rejection and wastage of material flow
  4. helps energy managers to focus on finding improvements in a prioritized manner
Answer: C) depicts rejection and wastage of material flow
Confirmed vs Book-1 §4.4 — A Sankey diagram is an ENERGY flow diagram: band widths show the input energy and each output and loss stream, letting the energy manager prioritise the biggest losses. It does not depict rejection and wastage of MATERIAL flow — that belongs to the process flow diagram / material balance, so (c) is the statement that does not apply.
Source: Apr 2010
📖 §4.12 Energy audit instruments — Ultrasonic Flow Meter

10. A non-contact method to measure the water flow through a metallic pipe is

  1. orifice meter
  2. turbine flow meter
  3. ultrasonic flow meter
  4. none of the above
Answer: C) ultrasonic flow meter
Confirmed vs Book-1 §4.12 — Book §4.12 describes the ultrasonic flow meter as the popular means of NON-contact flow measurement, with clamp-on transducers working through the metallic pipe wall. An orifice meter needs a plate inside the line and a turbine meter a rotor in the stream, so both are contact/intrusive; 'none of the above' is therefore wrong.
Source: Apr 2010
📖 §4.3 Need for Energy Audit

11. To identify the energy conservation opportunity in a plant, the best option is to carry out:

  1. energy audit
  2. training and awareness programme
  3. seminars and workshops
  4. analysis of the plant energy bills
Answer: A) energy audit
Confirmed vs Book-1 §4.3 — Book §4.3: the energy audit "will help to understand more about the ways energy is used ... and help in identifying the areas where waste can occur and where scope for improvement exists" — it is the translation of conservation ideas into realities. Training, seminars and bill analysis alone build awareness or give only macro data; bill analysis is merely one input to the preliminary audit.
Source: Apr 2010
📖 §4.12 Energy audit instruments — Manometer with Pitot Tube

12. Air velocity in ducts can be measured by using ___

  1. pyrometer
  2. bourdon gauge
  3. pitot tube and manometer
  4. anemometer
Answer: C) pitot tube and manometer
Confirmed vs Book-1 §4.12 — Book §4.12: "To measure pressure in air pipes, manometers must be used in combination with a pitot tube" — the velocity pressure so obtained gives duct air velocity. An anemometer measures air velocity too but is not among the Ch4 instruments, while a pyrometer reads high temperature and a Bourdon gauge static pressure only.
Source: Apr 2010
📖 §4.12 Energy audit instruments — Speed Measurements

13. Non contact speed measurements can be carried out by

  1. odometer
  2. tachometer
  3. stroboscope
  4. oscilloscope
Answer: C) stroboscope
Confirmed vs Book-1 §4.12 — Book §4.12: the stroboscope is the non-contact speed instrument — its high-intensity flashes, when matched in frequency to the rotation, appear to freeze the motion and so give RPM. The tachometer is the tempting distractor but the book calls it "a contact type instrument"; an odometer measures distance and an oscilloscope displays waveforms.
Source: Nov 2009
📖 §4.4 Step 6 Analysis of energy use / energy balance (Sankey detail in Book-1 Ch5 & Ch9)

14. The statement not applicable in the case of Sankey diagram

  1. useful tool to represent an entire input and output energy flow
  2. represents visually various outputs and losses
  3. depicts rejection and wastage of material flow
  4. helps energy manager to focus on finding improvements in a prioritized manner
Answer: C) depicts rejection and wastage of material flow
Confirmed vs Book-1 §4.4 — The Sankey diagram maps energy input against every useful output and loss, so options (a), (b) and (d) all apply. Depicting rejection and wastage of MATERIAL flow is the job of the process flow diagram and material balance, not the Sankey diagram, so (c) is the odd one out.
Source: Nov 2009
📖 §4.1 Energy management approach (see also Book-1 Ch6 Energy Action Planning)

15. The first vital step in an energy management program is

  1. measurement
  2. setting goals
  3. energy audit
  4. top management commitment
Answer: D) top management commitment
Confirmed vs Book-1 §4.1 — Book §4.1: successful energy management "begins with the key decision makers" and organisations must "give priority to energy management and make it an integral part of company management strategy" — i.e. top management commitment comes first. Measurement, goal-setting and the audit itself all follow once management has committed the resources and mandate.
Source: Nov 2009
📖 §4.1 Energy management approach (see also Book-1 Ch6 Energy Action Planning)

16. The four pillars of successful energy management are technical ability, monitoring system, top management support and ______

  1. strategy plan
  2. energy audit plan
  3. quality plan
  4. financial plan
Answer: A) strategy plan
Confirmed vs Book-1 §4.1 — The four pillars of a successful energy management programme are top management support, a strategy plan, a monitoring system and technical ability; with three named in the stem, the missing pillar is the strategy plan. An energy-audit plan, quality plan or financial plan are activities that flow FROM the strategy, not pillars in their own right.
Source: Nov 2009
📖 §4.12 Energy audit instruments — Speed Measurements

17. Stroboscope is an instrument for measuring

  1. steam flow
  2. composition of flue gas
  3. speed
  4. pressure
Answer: C) speed
Confirmed vs Book-1 §4.12 — Book §4.12: "A stroboscope uses this principle for measurement of RPM" — flashes of light at a precise frequency make periodic motion appear stopped. It is a speed instrument only; flue-gas composition needs a Fyrite/gas analyser, pressure a manometer and steam flow a flow meter.
Source: 2019
📖 §4.6 Benchmarking — Equipment/Utility related parameters

18. The benchmarking parameter for a vapour compression refrigeration system is

  1. kW / kg of refrigerant used
  2. kcal / m3 of chilled water
  3. BTU / Ton of Refrigeration
  4. kW / Ton of Refrigeration
Answer: D) kW / Ton of Refrigeration
Confirmed vs Book-1 §4.6 — Book §4.6 lists "kWh/ton of refrigeration (on Air-conditioning plant)" as the equipment-related benchmark, and adds that parity of chilled-water temperature must be stated when comparing kW/TR. kW per kg of refrigerant and kcal/m3 of chilled water are not standard metrics, and BTU/TR mixes an energy unit with a power unit.
Source: 2017
📖 §4.2 Energy Audit Definition (EC Act 2001)

19. Definition of Energy Audit as per EC Act does not include:

  1. Creation of an Energy Management System (EnMS)
  2. evaluation of Techno-economics
  3. Verification, monitoring and analysis of energy use
  4. Action plan required for energy saving
Answer: A) Creation of an Energy Management System (EnMS)
Confirmed vs Book-1 §4.2 — The EC Act 2001 definition quoted in §4.2 covers verification, monitoring and analysis of energy use, a technical report with recommendations and COST-BENEFIT (techno-economic) analysis, and an action plan to reduce energy consumption — options (b), (c) and (d). Creating an Energy Management System (EnMS/ISO 50001) is nowhere in that statutory definition.
Source: 2018
📖 §4.1 Energy management (EnMS standard; ISO 50001 detail in Book-1 Ch6)

20. The ISO standard for Energy Management System is

  1. ISO 14001
  2. ISO 50001
  3. ISO 9001
  4. ISO 18001
Answer: B) ISO 50001
Confirmed vs Book-1 §4.1 — ISO 50001 is the international standard for an Energy Management System, giving the plan-do-check-act framework for energy policy, targets and review. ISO 14001 is environmental management, ISO 9001 quality management and ISO 18001 (OHSAS) occupational health and safety.
Source: 2018
📖 §4.12 Energy audit instruments — Speed Measurements

21. RPM of an electric motor is measured using ___.

  1. Ultrasonic meter
  2. Stroboscope
  3. Lux meter
  4. Rotameter
Answer: B) Stroboscope
Confirmed vs Book-1 §4.12 — Book §4.12: the stroboscope is the non-contact instrument used for RPM measurement, which is why it is preferred on running motors where contact is unsafe. An ultrasonic meter measures flow, a lux meter illumination and a rotameter (variable-area meter) liquid/gas flow rate.
Source: 2018
📖 §4.12 Energy audit instruments — Psychrometer

22. A sling psychrometer is used to measure :

  1. only dry bulb temperature
  2. only wet bulb temperature
  3. both a & b
  4. relative humidity
Answer: C) both a & b
Confirmed vs Book-1 §4.12 — Book §4.12: a sling psychrometer "consists of two thermometers" — one ordinary (dry bulb) and one with a wet cloth wick (wet bulb) — and BOTH temperatures are read after whirling. Relative humidity is not measured directly: the book says "by using these temperatures the humidity is computed", so (d) is the tempting but wrong choice.
Source: 2017
📖 §4.1 Energy management (EnMS rationale; ISO 50001 detail in Book-1 Ch6)

23. Which among the following factor(s) is most appropriate for adopting EnMS?

  1. To improve their energy efficiency
  2. To reduce costs
  3. To increase productivity
  4. Systematically manage their energy use
Answer: D) Systematically manage their energy use
Confirmed vs Book-1 §4.1 — The defining purpose of an EnMS (ISO 50001) is to give an organisation a systematic, continual framework for managing energy use — policy, targets, measurement and review. Improved efficiency, lower cost and higher productivity are outcomes that follow from that system, not the reason the system itself is adopted.
Source: 2016
📖 §4.12 Energy audit instruments — Psychrometer

24. A sling psychrometer is capable of measuring

  1. only dry bulb temperature
  2. only wet bulb temperature
  3. both dry and wet bulb temperature
  4. absolute humidity
Answer: C) both dry and wet bulb temperature
Confirmed vs Book-1 §4.12 — Book §4.12: the sling psychrometer's two thermometers give the dry-bulb and the wet-bulb temperature, and humidity is then COMPUTED from the two readings. Absolute humidity is therefore a derived quantity, not something the instrument measures, so (d) is wrong.
Source: 2016
📖 §4.12 Energy audit instruments — Ultrasonic Flow Meter

25. Doppler effect principle is used in the following instrument

  1. lux meter
  2. ultrasonic flow meter
  3. infrared thermometer
  4. flue gas analyzer
Answer: B) ultrasonic flow meter
Confirmed vs Book-1 §4.12 — Book §4.12: "Doppler ultrasonic flow meters measure dirty liquids. They compute flow rate based on a frequency shift that occurs when their ultrasonic signals reflect off particles in the flow stream." A lux meter uses a light-sensitive cell, an IR thermometer thermal radiation and a flue-gas analyser chemical cells — none uses the Doppler effect.
Source: 2016
📖 §4.12 Energy audit instruments and metering

26. Liquid fuel density is measured by an instrument called

  1. Tachometer
  2. hygrometer
  3. anemometer
  4. none of the above
Answer: D) none of the above
Confirmed vs Book-1 §4.12 — Density of a liquid fuel is measured with a HYDROMETER (or by a density/specific-gravity bottle), which is not among the options. A hygrometer is the tempting look-alike but measures humidity, a tachometer measures speed and an anemometer air velocity — hence 'none of the above'.
Source: 2016
📖 §4.1 Energy management (EnMS framework; ISO 50001 detail in Book-1 Ch6)

27. ISO 50001:2011 provides a framework of requirements for organizations to:

  1. Develop a policy for more efficient use of energy
  2. Measure the results
  3. Fix targets and objectives to meet the policy
  4. all of the above
Answer: D) all of the above
Confirmed vs Book-1 §4.1 — ISO 50001:2011 requires an organisation to develop an energy policy, fix objectives and targets to meet that policy, use data to support decisions, measure the results and review the policy — so (a), (b) and (c) are all required elements and 'all of the above' is the only complete answer.
Source: 2016
📖 §4.12 Energy audit instruments — Ultrasonic Flow Meter

28. Transit time method is used in which of the instrument?

  1. Lux Meter
  2. Ultrasonic Flow Meter
  3. Pitot Tube
  4. Fyrite
Answer: B) Ultrasonic Flow Meter
Confirmed vs Book-1 §4.12 — Book §4.12: transit-time ultrasonic meters send signals with and against the flow; the signal with the flow travels faster and "the difference between these two timings is proportional to flow rate". A lux meter measures illumination, a pitot tube uses velocity pressure and a Fyrite uses chemical absorption — none uses transit time.
Source: Sep 2024
📖 §4.6 Benchmarking — Equipment/Utility related parameters

29. The energy benchmarking parameter for air conditioning equipment is

  1. kW/Ton of Refrigeration
  2. kW/ kg of refrigerant handled
  3. kW/m3 of chilled water
  4. kW/EER
Answer: A) kW/Ton of Refrigeration
Confirmed vs Book-1 §4.6 — Book §4.6 lists "kWh/ton of refrigeration (on Air-conditioning plant)" as the benchmark for A/C plant, i.e. kW/TR. kW/kg of refrigerant handled says nothing about cooling delivered, kW/m3 of chilled water ignores the temperature rise, and kW/EER is not a defined metric.
Source: 2013
📖 §4.12 Energy audit instruments — Fyrite

30. CO2 measurement in a Fyrite kit is based on

  1. Weight basis (dry)
  2. Volume basis (dry)
  3. Weight basis (wet)
  4. Volume basis (wet)
Answer: B) Volume basis (dry)
Confirmed vs Book-1 §4.12 — Book §4.12: "The FYRITE employs the well-known Orsat method of volumetric analysis using chemical absorption of a sample gas" — the gas sample is absorbed and the change in VOLUME is read on the scale. Orsat/Fyrite readings are on a dry basis because the moisture is not part of the absorbed volume, so it is volume basis (dry), not any weight basis.
Source: 2013
📖 §4.12 Energy audit instruments — Manometer with Pitot Tube

31. Air velocity in the ducts can be measured by using ___________ and manometer

  1. orifice meter
  2. Bourden gauge
  3. Pitot tube
  4. anemometer
Answer: C) Pitot tube
Confirmed vs Book-1 §4.12 — Book §4.12: the digital flexible-membrane manometer must be used "in combination with a pitot tube", inserted through a 6-cm monitoring hole in the duct, to measure the pressure from which duct air velocity is obtained. An anemometer would measure velocity by itself (no manometer), an orifice meter is an in-line liquid/gas element and a Bourdon gauge reads static pressure only.
Source: 2012
📖 §4.12 Energy audit instruments — Speed Measurements

32. Speed measurement (RPM) of an electric motor is measured with a

  1. stroboscope
  2. ultrasonic meter
  3. lux meter
  4. rotameter
Answer: A) stroboscope
Confirmed vs Book-1 §4.12 — Book §4.12: the stroboscope is the non-contact RPM instrument, flashing light at a precise frequency until the rotating object appears stationary. An ultrasonic meter measures flow, a lux meter illumination and a rotameter flow rate — none reads motor speed.
Source: 2012
📖 §4.1 Definition and Objectives of Energy Management (Book EOC Objective Q1)

33. 'The judicious and effective use of energy to maximise profits and enhance competitive positions'. This can be the definition of:

  1. energy conservation
  2. energy management
  3. energy policy
  4. energy Audit
Answer: B) energy management
Confirmed vs Book-1 §4.1 — This is the book's own definition in §4.1: energy management is "the judicious and effective use of energy to maximize profits (minimize costs) and enhance competitive positions". Energy conservation is the act of using less energy, an energy policy is the written commitment, and an energy audit (§4.2) is the verification/monitoring/analysis exercise.
Source: Guidebook
📖 §4.1 Energy management function (Book EOC Objective Q2; role detailed in Book-1 Ch6)

34. Role of energy manager is

  1. energy auditor and in charge of the finance department of the plant
  2. intermediate player between top management, energy and cost centres of the plant
  3. in charge of the captive power plant and mediator between plant and electricity boards
  4. as well as called production manager and project manager
Answer: B) intermediate player between top management, energy and cost centres of the plant
Confirmed vs Book-1 §4.1 — The energy manager is the link between top management and the plant's energy and cost centres — carrying management's commitment down to the shop floor and the audit findings back up. He is not the finance head, not the captive-power-plant in-charge, and not the production or project manager.
Source: Guidebook
📖 §4.7 Energy Performance — Production Factor

35. The ratio of current year's production to the reference year's production is

  1. demand factor
  2. production factor
  3. utilisation factor
  4. load factor
Answer: B) production factor
Confirmed vs Book-1 §4.7 — Book §4.7: "Production factor is the ratio of production in the current year to that in the reference year", used to work out the reference-year equivalent energy. Demand factor, utilisation factor and load factor are all electrical-loading ratios and involve no production output at all.
Source: Guidebook
📖 §4.1/§4.6 energy unit equivalence (Book EOC Objective Q5)

36. One unit of electricity is equivalent to ___ kcal heat units.

  1. 800
  2. 860
  3. 400
  4. 680
Answer: B) 860
Confirmed vs Book-1 §4.1/§4.6 — One unit of electricity (1 kWh) = 860 kcal of heat; this is the conversion used throughout the guidebook whenever electrical and thermal energy are added on a common basis (e.g. heat rate in kcal/kWh). 800, 400 and 680 kcal are simply wrong values for this standard equivalence.
Source: Guidebook
📖 §4.6 Benchmarking — Equipment/Utility related parameters (Book EOC Objective Q6)

37. The benchmarking parameter for air conditioning equipment is

  1. kW/Ton of refrigeration
  2. kW/kg of refrigerant handled
  3. kcal/m^3 of chilled water
  4. differential temperature across chiller
Answer: A) kW/Ton of refrigeration
Confirmed vs Book-1 §4.6 — Book §4.6 lists "kWh/ton of refrigeration (on Air-conditioning plant)" — power input per unit of cooling delivered. kW/kg of refrigerant handled and kcal/m3 of chilled water do not measure useful cooling per unit energy, and the differential temperature across the chiller is an operating parameter, not an energy benchmark.
Source: Guidebook
📖 §4.12 Energy audit instruments — Combustion Gas Analyzer vs Fyrite (Book EOC Objective Q7)

38. Which instrument is used to monitor O2, CO in flue gas?

  1. combustion analyzer
  2. power analyzer
  3. pyrometer
  4. fyrite
Answer: A) combustion analyzer
Confirmed vs Book-1 §4.12 — Book §4.12: the combustion gas analyzer "has in-built chemical cells which measure various gases such as CO2, CO, NOx, SOx" — so it is the instrument that can monitor BOTH O2 and CO. The Fyrite is the tempting distractor, but it absorbs one gas at a time (KOH for CO2, chromous chloride for O2) and cannot read CO; a power analyzer reads electrical parameters and a pyrometer temperature.
Source: Guidebook
📖 §4.6 Benchmarking — External benchmarking factors (Book EOC Objective Q9)

39. Which one of the following is not considered for external benchmarking:

  1. scale of operation
  2. vintage of technology
  3. energy price
  4. quality of raw material and products
Answer: C) energy price
Confirmed vs Book-1 §4.6 — Book §4.6 lists the comparative factors for external benchmarking as scale of operation, vintage of technology, raw material specification/quality and product specification/quality. Energy PRICE is not on that list — benchmarking compares physical specific energy consumption, and price varies by state, city and consumer (§4.5) without affecting how efficiently energy is used.
Source: Guidebook
📖 §4.12 Energy audit instruments — Ultrasonic Flow Meter (Book EOC Objective Q10)

40. Transit time method is used in which of the instruments

  1. lux meter
  2. ultrasonic flow meter
  3. Pitot tube
  4. fyrite
Answer: B) ultrasonic flow meter
Confirmed vs Book-1 §4.12 — Book §4.12: transit-time ultrasonic meters send one signal with and one against the flow and take the difference of the two travel times, which is proportional to flow rate. The lux meter uses a light-sensitive cell, the pitot tube velocity pressure and the Fyrite chemical absorption.
Source: Guidebook
📖 §4.7 Energy performance monitoring (scatter/trend-line detail in Book-1 Ch9 Monitoring & Targeting)

41. Large scattering on production versus energy consumption trend line indicates ____.

  1. Poor process monitoring
  2. Good level of control
  3. Poor level of control
  4. None of the above
Answer: C) Poor level of control
Confirmed vs Book-1 §4.7 — On a production-versus-energy-consumption plot the best-fit line is the expected energy relationship; points hugging the line mean consumption tracks output predictably. Wide scatter about that line means the same output was made with widely differing energy, i.e. a POOR level of control — 'good level of control' would show tight clustering.
Source: Mar 2023
📖 §4.1 Energy management function (Energy Manager duties; see also Book-1 Ch6)

42. Which of the following is the duty of an Energy Manager?

  1. Establish energy conservation cell
  2. Analyze equipment performance
  3. Develop and manage training programmes on energy efficiency
  4. All of the above
Answer: D) All of the above
Confirmed vs Book-1 §4.1 — The energy manager's statutory/functional duties include establishing an energy conservation cell, analysing equipment performance against design and benchmarks, and developing and managing energy-efficiency training programmes. Since each option is a genuine duty, 'all of the above' is the only complete answer.
Source: Mar 2023
📖 §4.4 Types of Energy Audit — Targeted Energy Audits

43. "Paper industry in Ghaziabad got its boiler audited and report generated", This statement refers to ____.

  1. Preliminary energy audit
  2. Detailed energy audit
  3. Targeted energy audit
  4. None of the above
Answer: C) Targeted energy audit
Confirmed vs Book-1 §4.4 — Book §4.4: "an organization may target its lighting system or boiler system or steam system ... Targeted audits therefore involve detailed surveys of the target subjects" and end in recommendations — exactly the boiler-only audit described. A preliminary audit is a quick walk-through using existing data, and a detailed audit covers ALL major energy-using equipment in the facility.
Source: Mar 2023
📖 §4.12 Energy audit instruments — Speed Measurements

44. Non-contact speed measurement can be carried out by ____.

  1. Tachometer
  2. Stroboscope
  3. Oscilloscope
  4. Speedometer
Answer: B) Stroboscope
Confirmed vs Book-1 §4.12 — Book §4.12: the stroboscope is the "more sophisticated and safer" NON-contact speed instrument, using high-intensity flashes at a precise frequency to freeze the motion and read RPM. The tachometer is the contact-type instrument, an oscilloscope displays waveforms and a speedometer reads linear vehicle speed.
Source: Jul 2022
📖 §4.12 Energy audit instruments and metering

45. A list of instruments and what they measure are given below. Which is the incorrect among this list?

  1. Gas analyzer - CO
  2. Lux Meter - Lumens
  3. Manometer- Pressure
  4. Tachometer - Speed
Answer: B) Lux Meter - Lumens
Confirmed vs Book-1 §4.12 — Illuminance is measured in LUX (lumens per square metre) — Book §4.12 says the light-sensitive cell's "measurement result in lux" — so pairing a lux meter with 'lumens' (the unit of luminous flux from a source) is the incorrect pairing. Gas analyzer–CO, manometer–pressure and tachometer–speed are all correct pairings in the same section.
Source: Jul 2022
📖 §4.1 Energy management (EnMS standard; ISO 50001 detail in Book-1 Ch6)

46. The ISO Series pertaining to the Energy Management System is ____.

  1. ISO 9001
  2. ISO 14001
  3. ISO 27000
  4. ISO 50001
Answer: D) ISO 50001
Confirmed vs Book-1 §4.1 — ISO 50001 is the ISO series for Energy Management Systems. ISO 9001 covers quality management, ISO 14001 environmental management and ISO 27000 information security — none of them is the energy standard.
Source: Jul 2022
📖 §4.9 Maximizing System Efficiencies (TPM practice; six big losses not listed in Ch4 text)

47. In Total Productive Maintenance (TPM), which of the following is not one of the six big losses that lower equipment efficiency?

  1. Breakdowns
  2. Idling and minor stoppages
  3. Reduced speed
  4. Excessive overtime hours
Answer: D) Excessive overtime hours
Confirmed vs Book-1 §4.9 — The six big losses in TPM are breakdowns, setup and adjustment, idling and minor stoppages, reduced speed, process defects/rework and reduced yield (start-up) losses — all of which lower Overall Equipment Effectiveness. Excessive overtime hours is a manpower/cost issue and is not one of the six equipment losses.
Source: Sep 2025
📖 §4.4 Step 6 Analysis of energy use / energy balance (Sankey detail in Book-1 Ch5 & Ch9)

48. Sankey diagrams help energy managers by:

  1. Prioritizing improvements based on visualized energy losses
  2. Reducing the need for energy audits
  3. Replacing thermodynamic calculations
  4. Eliminating the use of performance indicators
Answer: A) Prioritizing improvements based on visualized energy losses
Confirmed vs Book-1 §4.4 — A Sankey diagram draws each energy stream with a width proportional to its magnitude, so the largest losses are immediately visible and improvement effort can be prioritised where the money is. It supplements — never replaces — the energy audit, the thermodynamic calculations behind the balance, or the performance indicators used to track progress.
Source: Sep 2025
📖 §4.12 Energy audit instruments — Electrical Measuring Instruments

49. Which instrument measures power factor directly?

  1. Ammeter
  2. Wattmeter
  3. Lux meter
  4. Power analyzer
Answer: D) Power analyzer
Confirmed vs Book-1 §4.12 — Book §4.12: electrical measuring instruments (power analyzers) measure "KVA, KW, PF, Hertz, KVAr, Amps and Volts" on-line without stopping the motor, so power factor is read directly. An ammeter gives current only, a wattmeter active power only (PF then has to be computed with kVA) and a lux meter measures illumination.
Source: Sep 2025
📖 §4.4 Ten Steps Methodology for Conducting Detailed Energy Audit

50. Which of the following is a typical step in an energy audit?

  1. Data collection
  2. Analysis
  3. Reporting
  4. All of the above
Answer: D) All of the above
Confirmed vs Book-1 §4.4 — The book's ten-step methodology runs through primary data gathering (Step 3), survey/measurement and detailed trials (Steps 4-5), analysis of energy use (Step 6) and reporting and presentation to top management (Step 9) — so data collection, analysis and reporting are all typical steps and 'all of the above' is correct.
Source: Sep 2024
📖 §4.12 Energy audit instruments — Electrical Measuring Instruments

51. Which tool is commonly used for measuring power factor?

  1. Thermometer
  2. Hygrometer
  3. Anemometer
  4. None of the above
Answer: D) None of the above
Confirmed vs Book-1 §4.12 — Power factor is read with an electrical measuring instrument — a power analyser / PF meter (§4.12: measures KVA, KW, PF, Hertz, KVAr, Amps, Volts). A thermometer measures temperature, a hygrometer humidity and an anemometer air velocity, so none of the listed tools applies and 'none of the above' is correct.
Source: Sep 2024
📖 §4.7 Energy Performance — Plant Energy Performance

52. For calculating plant energy performance which of the following data is not required?

  1. Current year production
  2. Capacity Utilization
  3. Reference year production
  4. Reference year Energy use
Answer: B) Capacity Utilization
Confirmed vs Book-1 §4.7 — PEP needs only three inputs: reference-year energy use, the production factor (current year's production / reference year's production) and the current year's energy use. Capacity utilization never enters the formulae — PEP deliberately normalises for output via the production factor instead.
Source: Sep 2024
📖 §4.1 Energy management (EnMS rationale; ISO 50001 detail in Book-1 Ch6)

53. Which among the following factors is most appropriate for adopting EnMS?

  1. To improve their energy efficiency
  2. To reduce cost
  3. To increase productivity
  4. Systematically manage their energy use
Answer: D) Systematically manage their energy use
Confirmed vs Book-1 §4.1 — An EnMS is adopted to give a systematic, auditable framework for managing energy use — energy policy, planning, targets, measurement, review and continual improvement. Better efficiency, lower cost and higher productivity are the benefits that result, not the purpose of the system itself.
Source: Sep 2024
📖 Book-1 §4.12 — Speed Measurements

54. Which instrument is used for NON-CONTACT measurement of the speed (RPM) of a rotating machine?

  1. Tachometer
  2. Stroboscope
  3. Pitot tube
  4. Lux meter
Answer: B) Stroboscope
Confirmed vs Book-1 §4.12 — a tachometer is the CONTACT-type speed instrument, used where direct access to the shaft is possible. The stroboscope is the non-contact instrument: its light source gives high-intensity flashes at a precise frequency, so periodic motion appears slowed or stopped and RPM can be read. Pitot tube (duct velocity) and lux meter (illumination) have nothing to do with speed.
Source: AI practice
📖 Book-1 §4.12 — Fyrite

55. A Fyrite is used to measure:

  1. Velocity of gas in a duct
  2. Illumination level in lux
  3. O₂ or CO₂ content in flue gas
  4. Liquid flow rate
Answer: C) O₂ or CO₂ content in flue gas
Confirmed vs Book-1 §4.12 — in a Fyrite a hand-bellows pump draws the flue-gas sample into a chemical solution; the resulting change in liquid volume reveals the gas percentage, and OXYGEN or CO2 is read off the scale. It employs the Orsat method of volumetric analysis: potassium hydroxide (dyed red) absorbs CO2 and chromous chloride (blue) absorbs O2. Exam trap: the Fyrite does NOT read CO, NOx or SOx — those need the combustion gas analyzer.
Source: AI practice
📖 Book-1 §4.12 — Ultrasonic Flow Meter

56. The transit-time method for measuring flow of clean liquids is used by which instrument?

  1. Pitot tube
  2. Ultrasonic flow meter
  3. Tong tester
  4. Fyrite
Answer: B) Ultrasonic flow meter
Confirmed vs Book-1 §4.12 — transit-time ultrasonic meters have a sender and a receiver and send two signals across the pipe, one with the flow and one against it; the difference between the two transit times is proportional to flow rate. Transit-time meters usually monitor CLEAN liquids, while Doppler meters (frequency shift off particles) measure DIRTY liquids. Both are non-contact flow measurement.
Source: AI practice
📖 Book-1 §4.12 — Manometer with Pitot Tube

57. A pitot tube with a manometer is used to measure:

  1. Surface temperature
  2. Velocity / pressure of gas in ducts
  3. Power factor of a motor
  4. Humidity of air
Answer: B) Velocity / pressure of gas in ducts
Confirmed vs Book-1 §4.12 — the digital flexible-membrane manometer, used in combination with a pitot tube, measures pressure/velocity in air ducts carrying exhaust flue gases (boilers, furnaces) or air from fans and blowers. A 6-cm monitoring hole is made in the duct and the pitot tube inserted. Surface temperature is measured by the IR thermometer and humidity by the sling psychrometer.
Source: AI practice
📖 Book-1 §4.1 — Definition and Objectives of Energy Management

58. Energy management is best defined as:

  1. The complete elimination of all energy use
  2. The judicious and effective use of energy to maximise profits and enhance competitive position
  3. Switching entirely to renewable energy
  4. Auditing energy bills only
Answer: B) The judicious and effective use of energy to maximise profits and enhance competitive position
Confirmed vs Book-1 §4.1 — the book's verbatim definition is 'The judicious and effective use of energy to maximize profits (minimize costs) and enhance competitive positions.' The fundamental goal is to produce goods and provide services with the least cost and least environmental effect — not to eliminate energy use or merely audit bills.
Source: AI practice
📖 Book-1 §4.4 — Types of Energy Audit

59. A quick energy audit that uses existing/easily-obtained data to set a baseline and find low-cost savings is called a:

  1. Detailed (comprehensive) audit
  2. Targeted audit
  3. Preliminary (walk-through) audit
  4. Statutory audit
Answer: C) Preliminary (walk-through) audit
Confirmed vs Book-1 §4.4 — the preliminary energy audit, also known as the walk-through audit and diagnostic audit, is a relatively quick exercise using existing or easily obtained data. Its scope is to establish consumption from bills/invoices, estimate the scope for savings, identify the easiest areas and immediate no-/low-cost improvements, set up a baseline or reference point, and flag areas for more detailed study.
Source: AI practice
📖 Book-1 §4.6 — Benchmarking (external benchmarking)

60. Which of the following is NOT a factor considered in EXTERNAL benchmarking?

  1. Scale of operation
  2. Vintage of technology
  3. Energy price
  4. Raw material specification & quality
Answer: C) Energy price
Confirmed vs Book-1 §4.6 — the comparative factors to be carefully looked into while EXTERNAL benchmarking are exactly four: scale of operation, vintage of technology, raw material specifications & quality, and product specifications & quality. Energy price is not among them; if these four are not ascertained, benchmarking findings can be grossly misleading.
Source: AI practice
📖 Book-1 §4.7 — Plant Energy Performance

61. The Production Factor used in plant energy performance is defined as:

  1. Reference year production / Current year production
  2. Current year production / Reference year production
  3. Current year energy / Reference year energy
  4. Reference year energy × Current year production
Answer: B) Current year production / Reference year production
Confirmed vs Book-1 §4.7 — Production factor = current year's production / reference year's production. It is then used as: Reference year equivalent = reference year energy use x production factor, and PEP = (reference year equivalent - current year's energy) / reference year equivalent x 100.
Source: AI practice
📖 Book-1 §4.6 — Benchmark parameters (equipment/utility related)

62. The standard benchmark parameter (specific energy consumption) for an air-conditioning plant is:

  1. kWh/MT
  2. kcal/kWh
  3. kW/TR (kW per ton of refrigeration)
  4. kWh/Nm³
Answer: C) kW/TR (kW per ton of refrigeration)
Confirmed vs Book-1 §4.6 — under equipment/utility-related benchmarks the book lists kWh per ton of refrigeration for an air-conditioning plant (written kW/TR in the same section), and notes that parity of chilled-water temperature is crucial when comparing kW/TR. kcal/kWh is the heat rate of a power plant, kWh/MT applies to cement, and kWh/Nm3 to compressed air.
Source: AI practice
📖 Book-1 §4.13 — BEE (Manner and Intervals of Time for Conduct of Energy Audit) Regulations, 2008

63. Under the BEE (Manner and Intervals of Energy Audit) Regulations 2008, the first energy audit must be carried out within:

  1. 6 months of notification
  2. 12 months of notification
  3. 18 months of notification
  4. 36 months of notification
Answer: C) 18 months of notification
Confirmed vs Book-1 §4.13 — every designated consumer shall have its FIRST energy audit conducted by an accredited energy auditor within 18 months of the notification issued by the Central Government. The interval for subsequent audits is three years with effect from the date of submission of the previous audit report to the management of the designated consumer.
Source: AI practice
📖 Book-1 §4.2 — Energy Audit Definition (EC Act 2001)

64. As defined in the Energy Conservation Act 2001, an 'Energy Audit' means the verification, monitoring and analysis of use of energy, including submission of a technical report containing:

  1. Only a record of the electricity bills of the previous year
  2. Recommendations for improving energy efficiency with cost-benefit analysis and an action plan to reduce energy consumption
  3. A list of all employees trained in energy conservation
  4. The plant's safety and environmental clearance certificates
Answer: B) Recommendations for improving energy efficiency with cost-benefit analysis and an action plan to reduce energy consumption
Corrected (was a) — Book-1 §4.2: the original item asked which improvement cycle ISO 50001 runs on, which Chapter 4 does not cover at all (ISO 50001 appears only in §6.8, and the book there says it is 'based on the management system model of continual improvement', never naming PDCA for it). The question has therefore been rewritten to the definition given verbatim in §4.2: energy audit = the verification, monitoring and analysis of use of energy including submission of a technical report containing recommendations for improving energy efficiency with cost-benefit analysis and an action plan to reduce energy consumption.
Source: AI practice
📖 Book-1 §4.3 — Need for Energy Audit

65. In any industry the three top operating costs are usually energy, labour and materials. Which of these has the HIGHEST potential for cost reduction?

  1. Labour
  2. Materials
  3. Energy
  4. All three have equal potential
Answer: C) Energy
Corrected (was b) — Book-1 §4.3: the original item tested the Sankey diagram, which does not appear anywhere in Chapter 4 (it is §5.8, and the Chapter-5 bank already tests it). Rewritten to the opening line of §4.3: 'In any industry, the three top operating costs are often found to be energy (both electrical and thermal), labour and materials. Among the three, energy has the highest potential for cost reduction.' This is also why §4.5 stresses that energy cost is NOT a fixed overhead.
Source: AI practice

Short questions (5 marks) — 72

📖 §4.1 Definition and Objectives of Energy Management

1. Define energy management and state its fundamental goal.

Model answer: Energy management is "the judicious and effective use of energy to maximize profits (minimize costs) and enhance competitive positions." It is also defined as the strategy of adjusting and optimizing energy-using systems and procedures so as to reduce energy requirement per unit of output while holding constant or reducing total cost of producing that output. The fundamental goal is to produce goods and provide services with the least cost and least environmental effect.
Two marks sit on the quoted words. Learn the phrase by heart: "judicious and effective use of energy to maximize profits (minimize costs) and enhance competitive positions." Then add the goal line in your own words: same output, less energy per unit, cost not increased. Memory hook: energy DOWN per unit, profit UP, quality UNCHANGED. Common mistake: defining energy conservation or energy audit instead. Energy management is the whole strategy; the audit is only one tool inside it.
Source: Book/Concept
📖 §4.1 Definition and Objectives of Energy Management

2. State the objectives of energy management.

Model answer: The objectives of energy management are: (1) to achieve and maintain optimum energy procurement and utilisation throughout the organization; (2) to minimise energy costs and waste without affecting production and quality; and (3) to minimise environmental effects. Successful energy management combines an effective strategy with the right practical action, starting with key decision-makers and involving every employee day-to-day.
Write it as a numbered list of three, not a paragraph - the examiner ticks three items. Memory hook: COST - WASTE - ENVIRONMENT (optimum procurement and utilisation is the umbrella above all three). Note the guard clause "without affecting production and quality"; leaving it out is the usual lost mark. Close with one line that it needs top-management commitment plus every employee, since management sometimes carries a mark of its own.
Source: Book/Concept
📖 §4.2 Energy Audit Definition (EC Act 2001)

3. State the definition of energy audit as per the EC Act 2001.

Model answer: As per the EC Act 2001, "energy audit" means the verification, monitoring and analysis of use of energy, including submission of a technical report containing recommendations for improving energy efficiency with cost-benefit analysis and an action plan to reduce energy consumption. Energy audit is the key to a systematic approach for decision-making in energy management; it balances total energy inputs with their use and identifies/quantifies all energy streams in a facility according to discrete functions.
This is a legal definition, so reproduce it word-for-word from the EC Act 2001; paraphrasing costs marks. Memory hook - four things must appear: VERIFY, MONITOR, ANALYSE, then a technical REPORT that carries cost-benefit analysis and an action plan. Common mistake: stopping at "analysis of energy use" and forgetting the report, the cost-benefit analysis and the action plan - those are separate marks. If space allows, add the one-line function: it balances total energy input against use and finds the losses.
Source: Book/Concept
📖 §4.3 Need for Energy Audit

4. Why is an energy audit needed? Which of the top operating costs has the highest potential for cost reduction?

Model answer: In any industry the three top operating costs are usually energy (electrical and thermal), labour and materials; among these, energy has the highest potential for cost reduction. An energy audit helps understand how energy is used, identifies where waste occurs and where scope for improvement exists. It reviews variations in energy cost, availability and reliability of supply, decides the appropriate energy mix, and identifies energy conservation technologies and retrofits. In general it translates conservation ideas into reality through technically feasible solutions within economic and organizational constraints.
The examiner is looking for one fact first: of the three top operating costs - energy, labour, materials - ENERGY has the highest potential for cost reduction. State that in the first line. Then give the purpose in three short points: know where energy goes, find the waste, and prioritise where to act. Common mistake: naming labour or materials, or listing four costs. It is exactly three, and energy is the one you can attack. Finish with the aim: minimise energy cost per unit of output without hurting production or quality.
Source: Book/Concept
📖 §4.4 Types of Energy Audit and Approach

5. Name the three types of energy audit and briefly describe each.

Model answer: (1) Preliminary energy audit (also called Walk-Through or Diagnostic audit): a relatively quick exercise using existing or easily obtained data to establish baseline consumption and identify easy, no-/low-cost savings. (2) Targeted energy audit: arises from the preliminary audit and gives detailed data/analysis on one specified target system (e.g. lighting, boiler, steam or compressed-air system). (3) Detailed (comprehensive) energy audit: accounts for the energy use of all major equipment, builds an energy balance, considers interactive effects, and gives the most accurate savings/cost estimate with a detailed implementation plan.
Give the three names first, then one line each - names alone will not carry full marks. Memory hook: WIDE and shallow (preliminary), NARROW and deep (targeted), WIDE and deep (detailed). Common mistake: writing "walk-through" as a fourth type. Walk-through / diagnostic is just another name for the preliminary audit. Mention the order in which they occur: preliminary comes first and its findings decide what gets a targeted or detailed audit.
Source: Book/Concept
📖 §4.4 Targeted Energy Audits (Book EOC Short Q S-1)

6. Explain what is meant by a targeted energy audit.

Model answer: A targeted energy audit is a focused audit that often results from a preliminary audit. It provides data and detailed analysis on a specified target system or project rather than the whole plant — for example targeting the lighting system, boiler, steam system or compressed-air system to effect energy savings. It involves detailed surveys of the chosen target and analysis of the energy flows and costs associated with it, and its final outcome is specific recommendations regarding the actions to be taken.
The word to stress is TARGET - one chosen system, not the whole plant. Always name two or three examples (lighting, boiler, steam system, compressed air); the examiner expects concrete systems. Say where it comes from: it normally follows a preliminary audit that flagged that system. Common mistake: describing a full plant-wide detailed audit. Targeted = one system, deep data, its own recommendations and costs.
Source: Book/Concept (OCR S-1)
📖 §4.4 Preliminary vs Detailed Energy Audit (Book EOC Short Q S-2)

7. Explain the major differences between a preliminary energy audit and a detailed energy audit.

Model answer: A preliminary (walk-through / diagnostic) audit is a relatively quick exercise using existing or easily-obtained data; it establishes energy consumption, sets a baseline, finds obvious wastage and the easiest no-/low-cost savings, and identifies areas for more detailed study — needing little instrumentation or time. A detailed (comprehensive) audit accounts for the energy use of all major equipment, uses portable/on-line instruments for measurement and monitoring, builds full energy and material balances, evaluates the techno-economic feasibility (savings, cost, payback) of each measure, and produces a detailed report with a prioritised implementation action plan; it can take weeks to months.
Answer this as a two-column comparison, not two paragraphs. Name the three differences the examiner is marking: (1) TIME and effort - a quick walk-through vs weeks/months; (2) DATA DEPTH - existing bills and easily-obtained data vs measurements on all major equipment with portable instruments and an energy balance; (3) COST and OUTPUT - cheap, gives obvious no-/low-cost savings vs costly, gives the most accurate savings estimate and a full project implementation plan. Memory hook: TIME - DATA - COST. Common mistake: saying the preliminary audit uses no instruments at all; it uses little instrumentation, not none.
Source: Book/Concept (OCR S-2)
📖 §4.4 Preliminary Energy Audit — scope

8. What is the scope of a preliminary energy audit?

Model answer: The scope of a preliminary energy audit is to: establish energy consumption in the organization (from energy bills and invoices); obtain related data such as production to relate with energy consumption; estimate the scope for energy savings; identify the most likely and easiest areas for attention (e.g. unnecessary lighting, high temperature settings, leakages); identify immediate, especially no-/low-cost, improvements; set up a baseline or reference point for energy consumption; and identify areas needing more detailed study or measurement.
This is a list question - use numbered points and keep each to one line. The order is a logical chain: establish consumption (bills) -> get production data to relate to it -> estimate savings scope -> pick the easiest areas -> list immediate no-/low-cost actions -> flag what needs detailed study -> set a reference point for future work. The words the examiner wants are "baseline" and "no-cost / low-cost". Common mistake: drifting into detailed-audit work such as energy balance or 24-hour trials - those belong to the detailed audit, not here.
Source: Book/Concept
📖 §4.4 Preliminary Energy Audit — no-cost / low-cost measures

9. Give examples of no-cost and low-cost energy management measures.

Model answer: No-cost energy management measures include arresting leaks (steam, compressed air) and controlling excess air by adjusting the fan damper. Low-cost measures include shutting equipment when not needed (e.g. stopping idle running of motors) and replacing with appropriate lamps and luminaires. Areas needing more detailed study/measurement include converting from direct to indirect steam-heated equipment with condensate recovery, installing/upgrading insulation, modifying the process to reduce steam demand, rescheduling operations to cut peak demands, and recovering waste heat.
Split your answer under two clear headings: NO COST and LOW COST. One heading only loses half the marks. Memory hook: no cost = things you fix by turning a valve or a damper (stop leaks, adjust excess air). Low cost = things you switch off or swap cheaply (stop idle motors, change lamps and luminaires). Common mistake: putting VFDs, heat recovery, condensate recovery or new efficient equipment here - those are medium/high investment and belong in the detailed-study list. Link back to Table 4.3 grouping: A = no investment, B = low investment, C = high investment.
Source: Book/Concept
📖 §4.4 Detailed Energy Audit — energy balance

10. What is the energy balance in a detailed energy audit, and on what is it based?

Model answer: The energy balance is one of the key elements of a detailed energy audit. It is based on an inventory of energy-using systems, assumptions about current operating conditions, and measurements and calculations of energy use. By balancing the total energy inputs against their use, it identifies and quantifies all the energy streams and the losses/wastes in the facility, forming the basis for accurate savings estimates.
The examiner wants the phrase "key element of a detailed energy audit" plus the three things it is based on. Memory hook for the base: INVENTORY - ASSUMPTIONS - MEASUREMENTS (what you have, how it runs, what you measured). State the purpose in one line: input energy = useful energy + losses, so it quantifies every stream and every loss. Common mistake: confusing it with the material balance. Both are made in Step 6, but the energy balance is about energy streams, not raw materials.
Source: Book/Concept
📖 §4.4 Detailed energy auditing — Pre-Audit, Audit and Post-Audit phases

11. Name the three phases in which a detailed energy audit is carried out and the broad activities of each.

Model answer: A detailed energy audit is carried out in three phases: (a) Pre-Audit Phase — planning and organising the audit team, walk-through, instrument arrangement, macro data collection and an introductory meeting; (b) Audit Phase — primary data gathering, process-flow/energy-utility diagrams, surveys and monitoring, detailed trials/tests, energy and material balance, identifying ENCON opportunities, cost-benefit analysis, and reporting to top management; (c) Post-Audit Phase — implementation of recommendations, follow-up, monitoring and periodic review.
Name the three phases first: Pre-Audit, Audit, Post-Audit - then give 3-4 activities under each. Memory hook: PLAN - MEASURE - IMPLEMENT. Tie it to the ten steps if you are asked in the same paper: Steps 1-2 = Pre-Audit, Steps 3-9 = Audit, Step 10 = Post-Audit. Common mistake: forgetting the post-audit phase. Monitoring and follow-up carry marks - an audit is incomplete without them.
Source: Book/Concept
📖 §4.4 Ten Steps Methodology for Conducting Detailed Energy Audit

12. List the ten-step methodology for conducting a detailed energy audit.

Model answer: Step 1 Plan and organise (form audit team, walk-through, organise instruments). Step 2 Introductory meeting with divisional heads (rapport, awareness, issue questionnaires). Step 3 Primary data gathering, process flow and energy-utility diagrams (baseline). Step 4 Conduct survey and monitoring with portable instruments. Step 5 Conduct detailed trials/tests on major energy equipment (24-hr power, boiler/furnace efficiency). Step 6 Analysis of energy use — energy and material balance, loss analysis. Step 7 Identify and develop ENCON opportunities. Step 8 Cost-benefit analysis and prioritisation. Step 9 Reporting and presentation to top management. Step 10 Implementation and follow-up (monitoring and periodic review).
Write it as a numbered table: Step number, plan of action, purpose. Ten steps means ten lines - do not merge them. Memory hook, in three blocks: PLAN (1 organise, 2 introductory meeting) - MEASURE (3 primary data and flow diagrams, 4 survey with portable instruments, 5 detailed trials, 6 energy and material balance, 7 identify ENCON ideas, 8 cost-benefit and prioritise, 9 report and present to top management) - FOLLOW UP (10 implementation and monitoring). Common mistake: putting the reporting step in the post-audit phase; in the book Step 9 is still inside Phase II, and only Step 10 is post-audit. Add one closing line that the methodology is flexible and adapted to the industry.
Source: Book/Concept
📖 §4.4 Phase I — Pre Audit Phase (Book EOC Short Q S-3)

13. What are the areas that need to be focused during the pre-audit phase?

Model answer: During the pre-audit phase the focus is on planning, since proper planning is a prerequisite for an effective audit. Key actions/outcomes: discuss the aims of the audit with senior management and explain its purpose; analyse major energy consumption data with relevant personnel; obtain site drawings (plant layout, steam/compressed-air/electricity distribution); tour the site with a representative; finalise the energy audit team; know management's expectations; identify the main energy-consuming areas to survey; identify existing instrumentation and additional metering required; plan the audit with a time frame; collect macro data on energy resources and major equipment; and build awareness and support for the detailed audit.
One sentence opens it: proper planning is a pre-requisite for an effective audit, and the initial site visit should take only one day. Then split into ACTIONS (discuss aims with senior management, explain the purpose, discuss economic guidelines, analyse major consumption data, obtain site drawings, tour the site with a representative) and OUTCOMES (finalise the audit team, know management's expectations, identify main energy-consuming areas, identify existing and extra metering needed, plan the time frame, collect macro data, build awareness). The two words that earn marks: DRAWINGS and METERING - most students forget both. Common mistake: writing measurement or trial work here; no readings are taken in the pre-audit phase.
Source: Book/Concept (OCR S-3)
📖 §4.4 Phase I — Pre Audit Phase (questions the energy auditor should ask)

14. List the standard questions an energy auditor typically asks about each system during the initial site visit.

Model answer: During the initial site visit the energy auditor typically asks of each system: (1) What function does this system serve? (2) How does this system serve its function? (3) What is the energy consumption of this system? (4) What are the indications that this system is probably working? (5) If the system is not working, how can it be restored to good working condition? (6) How can the energy cost of this system be reduced? These questions structure the assessment of current operation and the search for savings.
There are SIX questions, not five or ten - count them as you write. Memory hook in pairs: what it does / how it does it - how much energy / how do we know it works - how to restore it / how to cut its cost. They run in a fixed logic: function, method, consumption, evidence of working, restoration, cost reduction. Common mistake: mixing these with the pre-audit action list. These are questions asked about EACH SYSTEM during the initial site visit.
Source: Book/Concept
📖 §4.4 Phase II — Detailed Energy Audit Phase (information to be collected)

15. What information is collected during the detailed energy audit phase?

Model answer: Information collected during the detailed audit includes: (1) sources of energy supplies (grid electricity or self-generation); (2) energy cost and tariff data; (3) generation and distribution of site services (compressed air, steam, water, chilled water); (4) process and material flow diagrams; (5) material balance data (raw materials, intermediates, final products, recycled/scrap, by-products); (6) energy consumption by type, department, major equipment and end-use; (7) potential for fuel substitution, process modification and cogeneration; and (8) review of ongoing energy management procedures and awareness/training programs.
A pure list question - number the items and keep each to a few words. Memory hook, follow energy from outside in: SUPPLY (source, tariff/cost) -> UTILITIES (compressed air, steam, water, chilled water) -> PROCESS (flow diagrams, material balance) -> CONSUMPTION (equipment-wise data) -> PEOPLE AND PLANS (operating practices, energy management procedures, future expansion). Give at least six items; a short answer with three items reads as incomplete. Common mistake: listing instruments here. Instruments are §4.12; this question is about INFORMATION.
Source: Book/Concept
📖 §4.4 Phase II — baseline data to be collected

16. What baseline data should the energy audit team ensure is collected?

Model answer: The team should ensure collection of: quantity and type of raw materials; technology, process and equipment used; capacity utilisation; efficiencies/yield; percentage rejection/reprocessing; quantity and types of wastes; and consumption of fuel, water, steam, electricity, compressed air, cooling water and chilled water. The auditor should specially interview supervisors and equipment operators (and the maintenance manager) who hold information on lighting, lamps, motor sizes, A/C plant, electrical load and performance problems.
Keep this separate in your mind from the previous list: baseline data is the plant's own operating numbers. Memory hook: INPUTS (raw materials, fuel, water, steam, electricity, compressed air, cooling and chilled water) - PROCESS (technology, equipment, capacity utilisation, efficiency/yield) - LOSSES (rejection/reprocessing, wastes). Do not miss the last line: the auditor must interview supervisors, operators and the maintenance manager. That people-side point is often a separate mark. Common mistake: giving only fuel and electricity. Baseline data covers all utilities plus production.
Source: Book/Concept
📖 §4.4 Preparing Process Flow Diagram (Figure 4.1 Penicillin-G)

17. What is the purpose of preparing a process flow diagram in an energy audit?

Model answer: A process flow diagram assembles an overview of unit operations, important process steps, material and energy use and waste generation. It is built using existing drawings, records and shop-floor survey, with the team identifying the various input and output streams at each step (including obvious wastes such as drained condensate and steam leakages). The audit focus then depends on consumption of input resources, energy-efficiency potential, the impact of a step on the entire process, and the intensity of waste/energy use — helping pinpoint major energy-conservation potential areas.
The purpose in one line: it gives an overview of unit operations and shows where material, energy and waste enter and leave each step. Then say how it is built - existing drawings, records and shop-floor survey - and that the team marks the input and output streams at every step, including obvious wastes such as drained condensate and steam leaks. Finish with why it matters: it tells you which step to audit first (highest input consumption, highest energy loss, highest waste). Common mistake: confusing it with the energy utility diagram. Process flow = the product route; utility diagram = the steam, air, water and power distribution route.
Source: Book/Concept
📖 §4.4 Identification of ENCON Opportunities

18. In which broad areas are energy conservation (ENCON) opportunities identified during an audit?

Model answer: ENCON opportunities are identified in four broad areas: (1) Fuel substitution — choosing the appropriate fuel for efficient energy conversion; (2) Energy generation — efficiency in conversion equipment, e.g. high-efficiency/optimally-loaded DG sets, boiler optimisation (minimum excess-air combustion), biomass gasifiers, cogeneration; (3) Energy distribution — efficiency in transformers, cables, switchgear, power-factor improvement, and chilled/cooling/hot water and compressed-air systems; and (4) Energy usage by processes — where the major (often hidden) opportunity lies, addressed through process analysis and process integration.
The examiner wants exactly FOUR headings, each with an example. Headings alone are half marks. Memory hook, follow the energy path: SUBSTITUTE the fuel -> GENERATE it efficiently -> DISTRIBUTE it with low loss -> USE it well. One clean example each: agro-residue for coal; optimally loaded DG set or cogeneration; power factor improvement and low-loss transformers/cables; VFDs, efficient motors and pumps. Common mistake: dumping all examples under "energy usage". Spread them across the four areas so each heading is earned.
Source: Book/Concept
📖 §4.4 Technical and Economic Feasibility

19. What issues are addressed under technical feasibility and economic viability when evaluating ENCON measures?

Model answer: Technical feasibility addresses: technology availability, space and skilled manpower; the impact of the measure on safety, quality, production or process; and reliability, service issues, maintenance requirements and spares availability. Economic viability is usually the key parameter for management acceptance and is assessed using the Payback method, Internal Rate of Return (IRR) and Net Present Value (NPV) methods. For low-investment, short-duration measures with attractive economics, the simple payback method is sufficient.
Answer under two headings - TECHNICAL FEASIBILITY and ECONOMIC VIABILITY - and give three points under each. Technical memory hook: RESOURCES (technology, space, skilled manpower) - IMPACT (safety, quality, production) - UPKEEP (reliability, service, maintenance, spares). Economic: name the three methods - Payback, IRR, NPV - and say economic viability is usually the key parameter for management acceptance. Common mistake: writing only payback. Naming IRR and NPV is a cheap extra mark.
Source: Book/Concept
📖 §4.4 Worksheet for Economic Feasibility

20. State the formulae for net savings per year and simple payback period used in the economic feasibility worksheet.

Model answer: Net Savings/year = Annual savings − Annual operating costs. Payback period (in months) = (Investment / Net Savings per year) × 12. In the worksheet, Investment covers equipment, civil works, instrumentation and auxiliaries; Annual operating costs cover cost of capital, maintenance, manpower, energy and depreciation; Annual savings cover thermal energy, electrical energy, raw materials and waste-disposal savings.
This is a formula question - write both formulas on their own lines, boxed, before any explanation. Net Savings/year = Annual savings - Annual operating costs. Payback (months) = (Investment / Net Savings per year) x 12. If the question asks in years, drop the 12. Common mistake: dividing investment by GROSS annual savings. You must subtract the annual operating cost first, and remember investment includes civil works, instrumentation and auxiliaries, not just the equipment price.
Source: Book/Concept
📖 §4.4 Classification of ENCON Measures

21. How are potential energy-saving (ENCON) measures classified, and which receive priority?

Model answer: ENCON measures are classified into three categories: (a) Low cost – high return; (b) Medium cost – medium return; and (c) High cost – high return. Normally the low cost–high return projects receive priority. Other projects are analysed, engineered and budgeted for phased implementation. Equipment- and process-change projects almost always involve high cost coupled with high returns, are complex, need long lead times, and require careful scrutiny before funds are committed.
Three categories, and you must also say which one gets priority - that is a separate mark. Memory hook: LOW cost-HIGH return first, then MEDIUM-MEDIUM, then HIGH-HIGH. Add the reason low-cost projects come first: quick returns, little risk, and they build management confidence for the big projects, which are phased and budgeted. Common mistake: forgetting the note that equipment and process-change projects are high cost with high return, complex, long lead time, and so are taken up in a planned, phased way.
Source: Book/Concept
📖 §4.4 Table 4.1 Project Priority Guideline

22. On what three feasibility dimensions are energy projects prioritised (A–D) in the project priority guideline?

Model answer: Projects are prioritised on three dimensions: Economical feasibility, Technical feasibility, and Risk feasibility. Priority A (good): well-defined and attractive economics, existing technology, no/adequate risk — highly feasible. Priority B (may-be): marginally acceptable economics, technology may need updating, minor operating risk — may be feasible. Priority C (held): poorly defined/marginally unacceptable economics, inadequate existing technology, doubtful risk. Priority D (no): clearly unattractive, needs a major technological breakthrough — not feasible.
Name the three dimensions in one line - ECONOMICAL, TECHNICAL, RISK feasibility - then describe A, B, C, D. Memory hook: A = good, B = may-be, C = held, D = rejected. Attractive economics and proven technology give A; poor economics or high risk pushes it to C or D. Do not confuse this with Table 4.3 (A/B/C by INVESTMENT level - no, low, high). This table grades projects by FEASIBILITY. Common mistake: giving only two dimensions. Risk feasibility is the one usually dropped.
Source: Book/Concept
📖 §4.4 Energy Audit Report

23. How should an energy audit report be structured, and how should the executive summary be written?

Model answer: The report should begin with an executive summary giving management a brief synopsis of total savings and a highlight of each energy-saving measure; it should be tailored to non-technical personnel. The main report starts with a general description of the process/facility, then annual energy consumption and bills (with tables and graphs), followed by a description of energy inputs/outputs by department or process and the efficiency of each step. Recommended ENCON measures are then presented with cost-benefit calculations and expected payback. It concludes with recommendations for detailed engineering studies and feasibility analyses for high-investment measures. The whole report should be clear, concise and easy to understand.
The one point the examiner wants first: the report OPENS with an executive summary aimed at non-technical management, giving total savings and a highlight of each measure. Then give the running order: process/facility description -> annual energy consumption and bills with tables and graphs -> energy inputs and outputs department-wise -> the energy conservation measures with savings, investment and payback -> action plan. Memory hook: SUMMARY FIRST, DETAIL AFTER - management reads only page one. Common mistake: burying the savings figures deep in the report or writing the summary in technical language.
Source: Book/Concept
📖 §4.4 Table 4.3 Types and Priority of Energy Saving Measures

24. Describe the A, B and C priority categories used for implementing energy-saving measures.

Model answer: Energy-saving measures are grouped by implementation priority: A — No Investment (Immediate): operational improvement and good housekeeping. B — Low Investment (Short to Medium Term): controls, equipment modification and process change. C — High Investment (Long Term): energy-efficient devices, product modification and technology change. This grouping (along with annual electricity/fuel savings) guides the order in which measures are scheduled.
Three categories by INVESTMENT and TIME - keep both attributes with each. Memory hook: A = No investment, immediate (housekeeping and operating improvement). B = Low investment, short to medium term (controls, equipment modification, process change). C = High investment, long term (efficient devices, product modification, technology change). Give one example under each - an example-free answer is treated as half done. Common mistake: mixing this up with the Table 4.1 A/B/C/D priority grades. Here A/B/C means investment level, not feasibility.
Source: Book/Concept
📖 §4.4 Phase III — Post Audit Phase

25. What is done in the post-audit phase regarding the energy action plan and monitoring?

Model answer: On completion of the audit, an energy action plan is prepared listing which ENCONs to implement first and suggesting an overall implementation schedule. An audit is incomplete without monitoring and feedback: monitoring consists of collecting and interpreting data (especially electrical power and fuel consumption), with data chosen per the goals in the action plan and fed back to those able to implement changes; additional sub-meters may be installed. Monitoring should lead to more action and replication of good practices. If the gap between planned objectives and actual achievements is large, reasons are analysed and new objectives/actions initiated — so analysis, action and monitoring form a cyclic process.
Two parts, so use two headings: ACTION PLAN and MONITORING. Action plan = what to implement first plus an overall implementation schedule. Monitoring = collect and interpret data (mainly electrical power and fuel), choose the data to suit the goals in the action plan, and feed results back to the people who can act on them. The line that earns the mark: an audit is INCOMPLETE without monitoring and feedback. Also mention that additional metering may be needed and that the whole thing is a repeating cycle of analysis, action and review.
Source: Book/Concept
📖 §4.5 Understanding Energy Costs — energy invoices

26. For what purposes can energy invoices be used in understanding energy costs?

Model answer: Energy cost is not a fixed overhead — there is often large savings potential. Where meters are insufficient, fuel/electricity invoices and the annual balance sheet are useful. Energy invoices can be used to: provide a record of energy purchased in a year, giving a baseline for future reference; indicate potential savings when related to production, air-conditioning or space-heating requirements; reveal maximum-demand-based purchase patterns; suggest where savings are most likely; and, in later years, quantify the energy and cost savings achieved through conservation measures.
Open with the key idea: energy cost is NOT a fixed overhead - it can be reduced. Then list what invoices give you: a record of the year's purchase (the baseline), savings potential when linked to production or heating/cooling load, maximum-demand and load-factor information, and a check on tariff and billing errors. Memory hook: BASELINE - RELATE TO OUTPUT - DEMAND PATTERN - CHECK THE BILL. Common mistake: forgetting to say invoices are used when metering is insufficient, along with the annual balance sheet.
Source: Book/Concept
📖 §4.5 Understanding Energy Costs — Power Costs

27. What factors are involved in deciding the final cost of purchased electricity?

Model answer: Factors deciding purchased-electricity cost include: maximum demand charges in kVA (how fast electricity is used); energy charges in kWh (how much is consumed); Time-of-Day (TOD) charges for peak/non-peak periods (when electricity is used); power-factor charge (real vs apparent power); other incentives and penalties; high-tension vs low-tension tariff rates; slab-rate costs and their variation; tariff clause/rate for categories (commercial, residential, industrial, government, agricultural); regional tariff differences; and tax holidays for new projects.
Answer as a list of charge heads, not prose. Memory hook - the four W's: HOW FAST (maximum demand in kVA), HOW MUCH (energy in kWh), WHEN (Time-of-Day peak/non-peak), HOW WELL (power factor charge). Then add HT vs LT rates, slab rates, penalties and incentives, and any tariff clause for high load factor or overdrawing. Keep the units right: demand in kVA, consumption in kWh - swapping them loses a mark. Common mistake: writing only energy charges. Demand, TOD and power factor are separate marks.
Source: Book/Concept
📖 §4.5 Understanding Energy Costs — Fuel Costs

28. What factors should be considered while procuring fuels for energy efficiency and economics?

Model answer: Fuel is purchased in tons or kilolitres, and availability, cost and quality are the three main factors. During procurement the factors to consider are: price at source, transport charge and type of transport; quality of fuel (contaminations, moisture, etc.); and energy content (calorific value). A wide variety of fuels is available for thermal energy — e.g. fuel oil, LSHS, LDO, lignite, coal, LPG and wood.
Start with the three main factors: AVAILABILITY, COST, QUALITY. Then the procurement points: price at source plus transport charge and mode; quality (moisture, contamination); and energy content, i.e. calorific value. Memory hook: PRICE - QUALITY - CALORIFIC VALUE. What matters is cost per unit of USEFUL heat, not cost per tonne. Round off with the list of thermal fuels the book names - fuel oil, LSHS, LDO, lignite, coal, LPG, wood - and note fuel is bought in tons or kilolitres.
Source: Book/Concept
📖 §4.6 Benchmarking (Book EOC Short Q S-4)

29. What is meant by energy benchmarking and how is it helpful?

Model answer: Energy benchmarking is a process in which the energy performance of an individual plant or an entire sector of similar plants is compared against a common metric representing 'standard' or 'optimal' performance (and may compare several plants against each other). The most common, size-independent metric is energy intensity = energy use per unit of output. It is helpful because it reveals the gap between current and best-achievable performance, sets realistic improvement targets, identifies inefficient/energy-intensive areas, and forms the basis for monitoring and target setting toward continuous improvement.
Give the definition, then the metric, then the benefit - three clean sentences. The metric to name is ENERGY INTENSITY = energy use per unit of output (specific energy consumption). The benefit line: it shows the gap between where you are and the best achievable, so targets become realistic and are set on evidence, not guesswork. Common mistake: comparing plants of different size or vintage without adjusting - always add the caution that the comparison must be like with like.
Source: Book/Concept (OCR S-4)
📖 §4.6 Benchmarking — features of a benchmark metric

30. What two features should a benchmarking metric have, and what is the most common metric?

Model answer: Because benchmark tools are applied to plants/sectors of different sizes and outputs, the metric must have two features: (1) it should be common irrespective of plant size; and (2) the tool should be usable in a wide range of facilities so as to compensate for differences in production at similar facilities. The most common metric used is energy intensity, which measures energy use per unit of output.
Only two features are wanted, so write them as (1) and (2) and stop - extra padding hides the answer. (1) The metric must be independent of plant size. (2) It must work across a wide range of facilities so it compensates for differences in production at similar plants. Then name the metric: energy intensity = energy use per unit of output. Common mistake: quoting total annual kWh or total fuel as the benchmark. Absolute consumption is size-dependent and is exactly what a benchmark metric must avoid.
Source: Book/Concept
📖 §4.6 Industrial Benchmarking Programs — three approaches

31. Describe the three approaches to energy benchmarking.

Model answer: (1) Evaluate an entire industrial sector (e.g. iron & steel, aluminium, cement) — comparing the sector against best available technology, against the same sector in other countries, and over time. (2) Compare individual plants within a sector (external/inter-unit benchmarking) — a benchmark indicator is computed for all facilities so they can be compared on even terms, while keeping indicators general enough not to reveal proprietary data. (3) Internal benchmarking — large companies set their own efficiency goals using their historical best performance as the benchmark, needing no disclosure of proprietary information.
Three approaches, each in one or two lines, and give an example industry for the first one. Memory hook by scope: SECTOR (whole industry vs best available technology, vs other countries, vs its own past) - PLANT vs PLANT (external / inter-unit benchmarking) - INSIDE ONE PLANT (process or equipment level, and against the plant's own historical best). Note the caution the book repeats for approach 2: proprietary data, so indicators must stay general enough not to reveal a company's confidential information. Common mistake: giving only external benchmarking. The sector-level and process-level approaches carry marks too.
Source: Book/Concept
📖 §4.6 External benchmarking — comparative factors

32. List the comparative factors that must be carefully examined while doing external benchmarking. Which common factor is NOT one of them?

Model answer: External benchmarking is inter-unit comparison across a group of similar units to identify best practices; the factors that must be carefully examined to ensure similarity are: (1) scale of operation; (2) vintage of technology; (3) raw material specifications and quality; and (4) product specifications and quality. Energy PRICE is NOT one of the external-benchmarking factors (a common trick option). If similarities are not ascertained, the findings can be grossly misleading.
Four factors, and one trap. Learn the four as two pairs: SCALE and VINTAGE (how big, how old the technology), RAW MATERIAL and PRODUCT specification and quality (what goes in, what comes out). The trap: energy PRICE is not a comparative factor. Price differs between locations but does not change how efficiently energy is used, so it never makes plants un-comparable. Add the closing line: if similarities cannot be established, benchmarking should be avoided or the figures normalised before comparing. Common mistake: adding location, climate or fuel price to the list. Stick to the four the book prints.
Source: Sep 2021 P1 / Mar 2023 / Book
📖 §4.6 Steps in energy conservation benchmarking

33. Summarise the steps in energy conservation benchmarking.

Model answer: (1) Identify the best available technology for the individual process units. (2) Collect information to thoroughly understand the process and identify the key/controlling parameters. (3) Determine the performance of the process unit. (4) Analyse the gap between the existing performance and the benchmark for the key controlling parameters. (5) Set targets or benchmarks, keeping constraints in view, and implement improvements based on the findings.
Five steps, in order - the sequence itself is what is being marked. Memory hook: FIND the best technology -> UNDERSTAND the process and its key parameters -> MEASURE your own performance -> COMPARE (gap analysis) -> SET the target and improve. The phrase to use is "key/controlling parameters" - the gap is analysed on those, not on total consumption. Common mistake: skipping the gap-analysis step and jumping from measurement to target setting.
Source: Book/Concept
📖 §4.6 Benchmark parameters — gross production related and equipment/utility related

34. Give examples of gross-production-related and equipment/utility-related benchmark (Specific Energy Consumption) parameters.

Model answer: Gross-production-related: kWh/MT clinker or cement (cement plant), kWh/kg yarn (textile), kWh/MT or kcal/kg paper (paper plant), kcal/kWh = heat rate (power plant), Million kcal/MT urea or ammonia (fertilizer plant), kWh/MT of liquid metal (foundry). Equipment/utility-related: kWh/ton of refrigeration i.e. kW/TR (A/C plant), % thermal efficiency (boiler plant), % cooling-tower effectiveness, kWh/Nm³ of compressed air generated, and kWh/litre in a diesel power-generation plant. Crucial process parameters must be stated alongside for meaningful comparison.
Split the answer clearly: GROSS PRODUCTION related (energy per tonne or per kg of PRODUCT) and EQUIPMENT / UTILITY related (energy per unit of SERVICE delivered). Give three or four examples on each side with correct units - the units are the marks. Cement kWh/MT clinker, textile kWh/kg yarn, power plant kcal/kWh heat rate, foundry kWh/MT liquid metal; then A/C plant kW/TR, boiler % thermal efficiency, cooling tower % effectiveness, compressor kWh/Nm3 air. Memory hook: all of these are just SEC = energy in / output out. Common mistake: writing kWh alone with no denominator - that is consumption, not a benchmark.
Source: Book/Concept
📖 §4.7 Energy Performance — Plant Energy Performance

35. What is Plant Energy Performance (PEP) and what does PEP monitoring compare?

Model answer: Plant Energy Performance (PEP) is a measure of whether a plant is now using more or less energy to manufacture its products than it did in the past — i.e. a measure of how well the energy management programme is performing. PEP monitoring compares the plant's energy use in a reference year with subsequent years, taking production output into account, to determine the improvement or deterioration. Because production varies year to year, the reference-year energy is adjusted (via the production factor) to give the energy that would have been needed for the current output, and this is compared with the actual current energy use.
Define PEP in one plain line: is the plant using more or less energy now than before, for the same output? The key word is COMPARISON - reference year against the current year, WITH production taken into account. Say why production must be adjusted: output changes year to year, so raw energy figures alone would mislead. That is exactly why the production factor exists. Common mistake: describing PEP as equipment-wise efficiency. PEP is a whole-plant, top-level indicator of how the energy management programme is doing.
Source: Book/Concept
📖 §4.7 Production Factor, Reference Year Equivalent and Plant Energy Performance

36. Define (i) Production Factor, (ii) Reference Year Equivalent, and (iii) Plant Energy Performance, with formulae.

Model answer: (i) Production Factor = Current year's production / Reference year's production — used to find the energy that would have been required for this year's output had the plant operated as in the reference year. (ii) Reference Year Equivalent = Reference year energy use × Production Factor — the energy that would have been used to produce the current year's output. (iii) Plant Energy Performance (%) = [(Reference Year Equivalent − Current year's energy) / Reference Year Equivalent] × 100 — the energy saved at the current rate of use compared to the reference year; the greater the improvement, the higher the (positive) number.
Write the three formulas in order, one line each; the marks are on the formulas, not on the words. Production Factor = Current year production / Reference year production; and Reference Year Equivalent = Reference year energy use x Production Factor. PEP (%) = [(Reference Year Equivalent - Current year energy) / Reference Year Equivalent] x 100. Memory hook: PF scales the OLD energy to the NEW output, then PEP is the percentage saving against that scaled figure. Common mistake: dividing by the current year's energy instead of the reference year equivalent, and forgetting the sign - positive PEP is improvement, negative is deterioration.
Source: Book/Concept (OCR L-1)
📖 §4.7 Solved Example — Plant Energy Performance

37. Reference year (2009) energy use = 12 million kcal, production factor for 2010 = 0.9, current year energy = 11 million kcal. Calculate the Plant Energy Performance (PEP) for 2010 and state your inference.

Model answer: Reference Year Equivalent = Reference year energy × PF = 12 × 0.9 = 10.8 Mkcal. PEP = [(Reference Year Equivalent − Current year energy) / Reference Year Equivalent] × 100 = [(10.8 − 11) / 10.8] × 100 = −1.85%. Inference: the plant energy performance is marginally negative (a slight deterioration), so the energy manager / plant manager has to take corrective action to improve the performance.
Show every step: first the reference year equivalent, then PEP, then the inference. Marks are split across all three. Do not skip the interpretation line - a negative PEP means the plant used MORE energy than it should have for that output, so performance has slipped and corrective action is needed. Watch the sign carefully. (10.8 - 11) is negative; students often flip the subtraction to get a positive answer and then write the wrong conclusion. Keep the units consistent (million kcal throughout) and quote the answer as a percentage.
Source: Book/Concept (Solved Example)
📖 §4.7 Energy Performance — PEP as starting point

38. Why is PEP considered the starting point for evaluating energy performance, and how often can it be reported?

Model answer: PEP is the starting point because it does not require detailed calculation of the energy used by every piece of equipment, process or building; instead it uses the most effective measure of energy savings — actual measured energy consumption compared with production output. Yearly comparisons minimise seasonal effects. Once a plant has started measuring yearly performance, management often wants more frequent information, and PEP can be used just as easily for monthly reporting as for yearly reporting.
Two things are being asked - WHY it is the starting point, and HOW OFTEN it can be reported. Answer both. Why: it needs no equipment-by-equipment calculation. It uses the most effective measure available - actual measured energy consumption compared with production output. How often: yearly to start with (yearly comparison cancels seasonal effects), then monthly once the system settles, because management wants information more frequently. Common mistake: forgetting to mention why the yearly basis is chosen. "Minimises seasonal variations" is the phrase the examiner is looking for.
Source: Book/Concept
📖 §4.8 Matching Energy Usage to Requirement (Book EOC Short Q S-5)

39. What do you understand by matching energy use to requirements? Give three examples.

Model answer: Matching energy use to requirement means correcting the mismatch between equipment capacity and user requirement (designers add safety margins, leading to oversized equipment) so that energy is supplied only as the process actually needs, avoiding part-load and wastage. Three examples: (1) eliminating throttling of a pump by impeller trimming, installing variable speed drives or resizing the pump; (2) eliminating damper operations in fans by impeller trimming, VSDs, pulley-diameter modification or fan resizing; (3) moderating chilled-water temperature to actual process needs and adopting task lighting in place of less-effective area lighting.
First give the reason the mismatch exists: designers add safety margins, so equipment ends up oversized and runs part-loaded. That one sentence sets up the whole answer. Then give exactly three examples with the fix named - throttled pump (trim the impeller, fit a VSD or resize the pump), damper-controlled fan (change the pulley, fit a VSD or resize the fan), and oversized motors, pumps, compressors, boilers or air-conditioning plant running at low load. Memory hook: SUPPLY SHOULD FOLLOW DEMAND, not the other way round. Common mistake: describing efficiency improvement instead. This section is about SIZE matching; §4.9 covers running the equipment efficiently.
Source: Book/Concept (OCR S-5)
📖 §4.9 Maximizing System Efficiencies

40. Give examples of measures for maximizing system efficiencies.

Model answer: After matching energy usage to sources, equipment should be operated efficiently through best O&M practices and best available technology. Examples: eliminating steam leakages using appropriate steam traps; maximising condensate recovery; adopting combustion controls for maximum combustion efficiency; replacing pumps, fans, air compressors, refrigeration compressors, boilers, furnaces and heaters wherever significant efficiency margins exist; and ensuring rated electrical parameters at the motor terminals.
Give four or five examples with a one-line reason each - a bare list scores low here. Memory hook, three routes: OPERATE better (best O&M practice, combustion controls, correct steam traps, condensate recovery) - REPLACE with better technology (efficient pumps, fans, compressors, boilers, furnaces) - MAINTAIN and TRAIN (regular maintenance, operator awareness). Say where this sits in the sequence: first you match energy use to requirement (§4.8), THEN you maximise system efficiency. Common mistake: repeating §4.8 examples like impeller trimming here. Keep sizing separate from efficiency.
Source: Book/Concept
📖 §4.10 Optimising Input Energy Requirements

41. What measures help in optimizing the input energy requirements?

Model answer: After fine-tuning energy-use practices, the input energy requirement is minimised by: maximising heat recovery from waste energy streams to reduce purchased energy; adopting cogeneration plants to balance heat and power requirements, reducing energy purchases; and adopting cost-effective renewable sources of energy such as solar, wind and biomass.
Only three measures are wanted - keep it tight. Memory hook: RECOVER (waste heat), COMBINE (cogeneration for heat and power together), RENEW (solar, wind, biomass). Open with the position in the sequence: this comes AFTER energy-use practices have been fine-tuned. The aim is to cut the energy you have to BUY. Common mistake: repeating housekeeping or efficiency measures here. This step is about reducing the INPUT energy requirement, not about running equipment better.
Source: Book/Concept
📖 §4.11 Fuel and Energy Substitution (with case study)

42. What is fuel substitution? Give examples of fuel substitution and of energy substitution.

Model answer: Fuel substitution is replacing an existing fossil fuel with a more efficient, less costly and less polluting fuel such as natural gas, biogas or locally available agro-residues. Examples of fuel substitution: natural gas as fuel/feedstock in fertilizer, petrochemical, power and sponge-iron industries; replacing coal with coconut shells or rice husk; replacing LDO with LSHS. There are two ways to reduce energy dependency — conservation and substitution. Examples of energy substitution: replacing electric heaters with steam heaters, and replacing steam-based hot water with solar systems.
The examiner is checking whether you can tell FUEL substitution from ENERGY substitution. Define and separate them. Fuel substitution = swap one fuel for a cheaper, cleaner, more efficient fuel (natural gas, biogas, agro-residues; coconut shell or rice husk for coal; LSHS for LDO). Energy substitution = change the FORM of energy delivering the same duty. The book's two examples are electric heaters replaced by steam heaters, and steam-based hot water replaced by solar systems. Common mistake: giving one example list for both. Remember the book's framing line - there are two ways to reduce energy dependency: energy conservation and substitution.
Source: Book/Concept
📖 §4.12 Key Performance Parameters for Energy Audit

43. What are the key performance parameters (electrical and non-electrical) measured in an energy audit?

Model answer: Basic electrical parameters (AC & DC): voltage (V), current (I), power factor, active power (kW), maximum demand (kVA), reactive power (kVAr), energy consumption (kWh), frequency (Hz) and harmonics. Important non-electrical parameters: temperature and heat flow, radiation, air and gas flow, liquid flow, RPM, air velocity, noise and vibration, dust concentration, TDS, pH, moisture content, relative humidity, and flue-gas analysis (CO₂, O₂, CO, SOₓ, NOₓ) with combustion efficiency.
Two headings: ELECTRICAL and NON-ELECTRICAL. Writing one long mixed list loses structure marks. Electrical memory hook: V, I, PF, kW, kVA, kVAr, kWh, Hz, harmonics - voltage and current first, then power in its three forms, then energy, frequency and harmonics. Non-electrical memory hook by medium: HEAT (temperature, heat flow, radiation, flue-gas composition) - FLOW (air, gas, liquid, air velocity) - MECHANICAL (RPM, noise, vibration) - QUALITY (dust, TDS, pH, moisture, relative humidity). Common mistake: naming the instruments instead of the parameters. Here the question asks for PARAMETERS.
Source: Book/Concept
📖 §4.12 Energy audit instruments and metering

44. What parameters are measured with the following instruments? (a) Pitot tube (b) Stroboscope (c) Fyrite (d) Lux meter (e) Power analyser.

Model answer: (a) Pitot tube (with manometer) — velocity/pressure of moving gases in air ducts of boilers, furnaces, fans and blowers; (b) Stroboscope — speed/RPM (non-contact); (c) Fyrite — O₂ or CO₂ in flue gas; (d) Lux meter — illumination/light level in lux; (e) Power analyser — kW, kVA, kVAr, power factor, frequency (Hz), current and voltage (and harmonics on advanced models).
One line per instrument, parameter only - no working principle unless asked. Full marks come from precision. The two traps in this set: FYRITE reads only CO2 or O2 - never CO (CO needs a combustion gas analyser); LUX METER reads illumination in LUX, not lumens (lumen is the lamp's output, lux is what falls on the surface). Stroboscope is NON-CONTACT speed; its contact-type twin is the tachometer. Do not swap them. Pitot tube must be written with a manometer - the pitot tube senses the pressure, the manometer reads it, and velocity is derived from it.
Source: Dec 2009 P1 Set A / Book
📖 §4.12 Energy audit instruments and metering

45. Write the parameters measured by the following instruments: (a) Stroboscope (b) Sling Psychrometer (c) Fyrite (d) Tachometer (e) Pitot tube.

Model answer: (a) Stroboscope — speed/RPM (non-contact); (b) Sling Psychrometer — dry-bulb and wet-bulb temperatures (used to compute humidity); (c) Fyrite — O₂ or CO₂ in flue gases; (d) Tachometer — speed/RPM (contact type); (e) Pitot tube — velocity (pressure) of moving gases in ducts.
This set deliberately puts stroboscope and tachometer side by side. Both measure speed / RPM - the difference is the marking point: TACHOMETER = contact type, STROBOSCOPE = non-contact. Sling psychrometer gives TWO temperatures - dry bulb and wet bulb. Humidity is calculated from them, not read directly, so say "used to find humidity" rather than "measures humidity". Fyrite = O2 or CO2 in flue gas only. Writing CO here is the standard lost mark. Pitot tube (with manometer) = velocity/pressure of gases in ducts.
Source: Last-10-yr compilation / Book
📖 §4.12 Energy audit instruments and metering

46. Name the instrument used to measure each of the following in an energy audit: (a) O₂, CO, CO₂ and temperature in flue gas; (b) Illumination levels; (c) Non-contact speed measurement; (d) kW, kWh, kVAr, kVA and power factor; (e) Non-contact surface temperature.

Model answer: (a) Combustion (flue gas) analyser; (b) Lux meter; (c) Stroboscope; (d) Power analyser; (e) Non-contact infrared (IR) thermometer.
This is the reverse question - parameter given, instrument wanted. Answer with the instrument name only, one line each. The giveaway in (a) is CO. The moment CO appears, the answer is a combustion (flue gas) ANALYSER, never a Fyrite - the Fyrite cannot read CO. In (c) "non-contact speed" means stroboscope; if it had said contact, the answer would be tachometer. In (e) "non-contact temperature" means infrared thermometer; a contact thermometer is a thermocouple probe. For (d), the single instrument covering kW, kWh, kVA, kVAr and PF together is the power analyser (clamp-on type is applied on-line without stopping the motor).
Source: Jul 2010 P1 Set A
📖 §4.12 Energy audit instruments and metering

47. Match the following instruments with the parameter/principle: A. Fyrite, B. Combustion gas analyser, C. Psychrometer, D. Stroboscope, E. Ultrasonic flowmeter — with — 1. CO₂, 2. CO, 3. Wet-bulb temperature, 4. Speed, 5. Transit time.

Model answer: A. Fyrite – 1. CO₂ (also O₂); B. Combustion gas analyser – 2. CO (also CO₂, NOₓ, SOₓ); C. Psychrometer – 3. Wet-bulb temperature (and dry-bulb); D. Stroboscope – 4. Speed (non-contact RPM); E. Ultrasonic flowmeter – 5. Transit time (transit-time/Doppler flow measurement).
In a matching question, do the certain pairs first and let the rest fall out. Speed -> stroboscope, wet bulb -> psychrometer, transit time -> ultrasonic flow meter are all unambiguous. The only real decision is CO2 vs CO. Fyrite takes CO2 (it reads CO2 or O2 only); the combustion gas analyser takes CO (it also does CO2, NOx, SOx). Getting this pair the wrong way round is the classic error. "Transit time" is the tell-tale phrase for the ultrasonic flow meter - the other type is Doppler. Write the final answer as clean pairs (A-1, B-2, C-3, D-4, E-5); do not explain unless asked.
Source: Mar 2023 (23rd Exam)
📖 §4.12 Energy audit instruments and metering

48. What parameters are measured with the following instruments? (a) Pitot tube (b) Stroboscope (c) Fyrite (d) Psychrometer (e) Anemometer.

Model answer: (a) Pitot tube — static, dynamic and total pressure of gas (velocity of moving gases); (b) Stroboscope — speed/RPM (non-contact); (c) Fyrite — CO₂ or O₂ in flue gas; (d) Psychrometer — dry-bulb and wet-bulb temperature; (e) Anemometer — air or wind velocity. (Anemometer is not in the Ch4 instrument list; the other four are.)
Four of the five are the standard §4.12 instruments; the ANEMOMETER is the odd one - it measures air or wind VELOCITY. Answer it anyway, but note it is not part of the chapter's instrument list. For the pitot tube, the fuller answer is static, dynamic (velocity) and total pressure of the gas - velocity is then derived from the pressure difference. Fyrite = CO2 or O2, never CO. Stroboscope = non-contact RPM (tachometer is the contact one). Psychrometer gives dry-bulb AND wet-bulb temperature - always write both, one temperature only is half marks.
Source: Last-10-yr compilation
📖 §4.12 Psychrometer

49. Write a short note on the psychrometer.

Model answer: A sling psychrometer consists of two thermometers mounted together with a handle. One is an ordinary thermometer measuring the dry-bulb temperature; the other has a wet cloth wick over its bulb and is the wet-bulb thermometer. When a reading is taken the psychrometer is whirled (swung) around; water evaporates from the wick, cooling the wet-bulb thermometer. Both temperatures are then read. Drier surrounding air causes more evaporation and a greater difference between the two readings. From these dry- and wet-bulb temperatures, the relative humidity is computed.
Structure a short note as: what it is -> how it works -> what you get from it. The mechanism is the marking point: the wet wick loses water by evaporation, evaporation takes heat, so the wet-bulb thermometer reads LOWER. Whirling it keeps fresh air passing over the wick. The rule to state: the drier the surrounding air, the more evaporation, so the bigger the gap between dry-bulb and wet-bulb. Equal readings mean saturated air. Common mistake: saying it measures humidity directly. It measures two temperatures; humidity is read off a psychrometric chart or table from them.
Source: Book/Concept (OCR L-2)
📖 §4.12 Non Contact Infrared Thermometer

50. Write a short note on the non-contact infrared (IR) thermometer.

Model answer: An infrared thermometer measures the amount of thermal (infrared) radiation emitted from an object. By knowing the object's emissivity and the amount of IR energy it emits, the object's temperature is determined. It allows measurement of temperatures of objects in hazardous or hard-to-reach places (non-contact). The most common design uses a lens to focus the infrared energy onto a detector; the detector converts the energy into an electrical signal that is displayed in units of temperature after correction for ambient-temperature variation.
Three parts win the marks: PRINCIPLE (measures the infrared radiation emitted by the object), INPUT NEEDED (the object's emissivity), and CONSTRUCTION (a lens focuses the IR energy onto a detector, which converts it to an electrical signal displayed as temperature). The application line: it lets you measure hot, moving, live or hard-to-reach surfaces safely, without contact - for example insulation surfaces, furnace walls, steam lines, motor and bearing housings. Memory hook: NO TOUCH - reads what the surface radiates. Common mistake: forgetting emissivity. Set the wrong emissivity and the reading is wrong - that point is often worth a mark on its own. Its contact-type counterpart is the thermocouple contact thermometer.
Source: Book/Concept (OCR L-2)
📖 §4.12 Speed Measurements — Stroboscope

51. Write a short note on the stroboscope.

Model answer: Speed measurements are critical in an audit as speed varies with frequency, belt slip and loading. A simple tachometer is a contact-type instrument used where direct access is possible; a more sophisticated and safer non-contact instrument is the stroboscope. A stroboscopic light source gives high-intensity flashes of light at a precise frequency. When this light falls on an object with periodic motion, the motion appears slowed or stopped when the two frequencies bear a definite relationship — the stroboscope uses this principle to measure RPM without contact.
Open with why speed matters in an audit: speed varies with frequency, belt slip and loading, so measured RPM is needed to judge motor and drive loading. Then draw the contrast the examiner wants: TACHOMETER = simple, contact type, used only where direct access is possible. STROBOSCOPE = non-contact, safer, and sophisticated. The principle: a high-intensity light flashes at a precise, adjustable frequency; when the flash rate matches the rotation speed the moving object appears to stand still, and the flashing frequency is then read as the RPM. Common mistake: writing that it measures vibration or that it is a contact instrument.
Source: Book/Concept (OCR L-2)
📖 §4.12 Manometer with Pitot Tube

52. Write a short note on the pitot tube (with manometer).

Model answer: A digital flexible-membrane manometer used with a pitot tube measures pressures (velocity) in air ducts carrying exhaust flue gases of boilers and furnaces, or air from fans and blowers. To measure, flexible rubber tubes are attached to the inlet and outlet probes of the manometer and to the ends of the pitot tube (tightened to prevent air leakage), a roughly 6-cm monitoring hole is made in the duct/pipeline, and the pitot tube is inserted into the hole. The pressure difference indicates the gas velocity.
Say the pair clearly: the PITOT TUBE senses the pressure, the MANOMETER displays it, and velocity is worked out from the pressure. Neither is complete without the other. Give the application: velocity/pressure of exhaust flue gases in boiler and furnace ducts, and of air from fans and blowers. If method steps are asked, keep the book's order: connect flexible rubber tubes from the manometer probes to the pitot tube ends and tighten them to prevent leakage, make the monitoring hole (about 6 cm) in the duct, insert the pitot tube and take the reading. Common mistake: saying it measures flow rate directly. It gives velocity; flow = velocity x duct area.
Source: Book/Concept (OCR L-2)
📖 §4.12 Fyrite (Orsat method of volumetric analysis)

53. Explain how the Fyrite works and what it measures.

Model answer: In the Fyrite, a hand-bellows pump draws a flue-gas sample into the solution inside the instrument; a chemical reaction changes the liquid volume, revealing the gas percentage, and O₂ or CO₂ is read from the scale. It employs the well-known Orsat method of volumetric analysis using chemical absorption of the sample gas — potassium hydroxide (dyed red) absorbs CO₂, and chromous chloride (blue) absorbs O₂. Its unique feature is that the absorbing fluid is also the indicating fluid, so one vessel replaces both the measuring burette and the absorption pipette.
The three things being marked: the METHOD (Orsat method of volumetric analysis by chemical absorption), the CHEMICALS (potassium hydroxide, dyed red, absorbs CO2; chromous chloride, blue, absorbs O2), and the PROCEDURE (a hand bellows pump draws the flue-gas sample into the solution; the liquid volume changes and the percentage is read off the scale). Say plainly what it does NOT do: the Fyrite reads CO2 or O2 only. It cannot read CO - that needs a combustion gas analyser. This distinction is asked again and again. Memory hook for the colours: RED for CO2 (KOH), BLUE for O2 (chromous chloride). One instrument reads one gas, so state which type of Fyrite you are using.
Source: Book/Concept
📖 §4.12 Combustion Gas Analyzer and Fuel Efficiency Monitor

54. What does a combustion gas analyzer measure, and how does it differ from a fuel efficiency monitor?

Model answer: A combustion gas analyzer has in-built chemical cells/sensors that measure various gases such as CO₂, CO, NOₓ and SOₓ; sensors can be changed for different components, but because a maximum of two sensors can be connected, only two or three parameters are measured at a time. A fuel efficiency monitor measures the oxygen and the temperature of the flue gas; calorific values of common fuels are fed into its microprocessor, which then calculates the combustion efficiency. The gas analyzer is lighter and easier to handle than the fuel efficiency monitor.
Answer this as a comparison, since the question says "how does it differ". COMBUSTION GAS ANALYSER: chemical cells/sensors read the actual gases - CO2, CO, NOx, SOx. Give the limit the book prints: a maximum of two sensors can be connected, so only two or three parameters at a time. FUEL EFFICIENCY MONITOR: measures only OXYGEN and flue-gas TEMPERATURE, and its microprocessor - which already holds the calorific values of common fuels - CALCULATES combustion efficiency from them. Memory hook: the analyser MEASURES the gases; the monitor CALCULATES efficiency from O2 and temperature. Common mistake: saying the fuel efficiency monitor measures CO or efficiency directly.
Source: Book/Concept
📖 §4.12 Electrical Measuring Instruments (with safety precautions)

55. What do electrical measuring instruments (power analysers/clamp meters) measure, and what safety precautions apply?

Model answer: Electrical measuring instruments measure major electrical parameters such as kVA, kW, PF, Hz, kVAr, amps and volts (some also measure harmonics). They are applied on-line on running motors without stopping them; hand-held meters give instant readings while advanced units give cumulative readings with printouts at set intervals. Safety precautions: never attach the clamp to a circuit operating above the maximum rated voltage or over bare conductors (to avoid short circuits and life-threatening hazards); and use rubber gloves, boots and a safety helmet, and never use the instrument with wet hands, to avoid electric shock.
Two parts, so split the answer: PARAMETERS then PRECAUTIONS. Answering only the parameters loses half. Parameters memory hook: kVA, kW, PF, Hz, kVAr, A, V - plus harmonics on advanced meters. Add the practical point that clamp-on meters work on-line on running motors, hand-held units give instant readings and advanced units log cumulative data with printouts. Precautions to name: never exceed the meter's rated voltage or current; check the insulation of the clamp and leads; use gloves and stand on an insulated mat; keep the meter and hands away from live bare conductors; do not use a damaged instrument. Common mistake: writing kWh readings without the demand and power-factor parameters, and skipping safety altogether.
Source: Book/Concept
📖 §4.12 Ultrasonic Flow Meter — transit time and Doppler

56. How does an ultrasonic flow meter work, and what is the difference between its transit-time and Doppler types?

Model answer: The ultrasonic flow meter is a popular non-contact flow measurement device. A transit-time meter has both a sender and a receiver; it sends two ultrasonic signals across the pipe — one with the flow and one against it. The signal travelling with the flow is faster; the meter measures the transit time of both, and the difference between the two timings is proportional to the flow rate. Transit-time meters usually monitor clean liquids, whereas Doppler ultrasonic meters measure dirty liquids, computing flow rate from the frequency shift caused when their signals reflect off particles in the flow stream.
The difference between the two types is the whole question. Learn it as a one-line rule: TRANSIT TIME for CLEAN liquids, DOPPLER for DIRTY liquids (those with particles or bubbles). Transit time: signals are sent both with and against the flow; the one going with the flow arrives sooner, and the TIME DIFFERENCE is proportional to flow rate. Doppler: the signal reflects off particles or bubbles moving in the liquid and comes back with a shifted frequency; the frequency shift gives the velocity. Say once that it is a NON-CONTACT, clamp-on instrument - no pipe cutting, so it can be used on a running plant. Common mistake: swapping clean and dirty between the two types.
Source: Mar 2023 (23rd Exam)
📖 §4.12 Contact Thermometer

57. What does a contact thermometer measure and how?

Model answer: Contact thermometers are thermocouples that measure, for example, flue-gas, hot-air and hot-water temperatures by inserting the probe directly into the stream. For measuring a surface temperature, a leaf-type probe is used with the same instrument. They are contact-type devices (unlike the non-contact infrared thermometer/thermography that sense emitted radiation).
Short answer, but be precise: contact thermometers are THERMOCOUPLES; the probe is inserted directly into the stream - flue gas, hot air, hot water. Add the accessory: for a SURFACE temperature, a LEAF-TYPE probe is used with the same instrument. That detail is usually the extra mark. Always finish with the contrast: contact type touches the medium; the infrared thermometer and thermography sense radiation without touching. Examiners pair these in the same question. Common mistake: describing it as non-contact, or leaving out what it is actually used on.
Source: Book/Concept
📖 §4.12 Thermography

58. What is thermography and what is it used for in energy audits?

Model answer: Thermography is infra-red thermal monitoring and imaging (non-contact type) that measures the thermal-energy radiation from the hot/cold surfaces of an object, providing input for assessing equipment health and predictive maintenance. The thermal-camera unit converts the electromagnetic thermal (IR) energy radiated by the object into electronic video signals, which are amplified and transmitted to a display monitor where the resulting image is analysed and interpreted for hot/cold spots.
Define it in the book's words: infra-red thermal monitoring and imaging, NON-CONTACT type, measuring the thermal radiation from hot or cold surfaces. Then the working chain: the thermal camera converts radiated IR energy into electronic video signals, which are amplified and shown on a monitor as a thermal image where colour indicates temperature. The use in an audit is the marking point: it finds hot spots and defects without shutdown - loose electrical joints, overloaded cables, damaged refractory, missing or wet insulation, faulty steam traps, hot bearings - so it feeds predictive maintenance. Memory hook: an IR thermometer gives ONE POINT reading, thermography gives a PICTURE of the whole surface.
Source: Book/Concept
📖 §4.12 Lux Meters and Smart Energy Meters

59. Explain the working of a lux meter and a smart energy meter.

Model answer: Lux meter: a light-sensitive cell measures the incident light (all light in the visible spectrum) and evaluates it against the human daylight-sensitivity curve, giving the result in lux; basic cells need a different correction factor for each light spectrum, while expensive single-cell meters use optical filters/lenses tuned to the eye's sensitivity (one correction value for any spectrum). Smart energy meter: usually an electric meter that keeps detailed real-time usage statistics (can also be used for fuel/water); it uses wireless communication to track consumption, is easily installed, gives accurate readings, and can be monitored/controlled via mobile or internet to save electricity and money.
Two instruments, so use two headings. Do not run them together. LUX METER: a light-sensitive cell measures the incident light in the visible spectrum, evaluated against the human daylight-sensitivity curve, and the result is read in LUX. Basic cells need a different correction factor for each light spectrum; costly single-cell meters use optical filters/lenses matched to the eye, so one correction value works for any spectrum. SMART ENERGY METER: an electric meter (also usable for fuel or water) that keeps detailed usage statistics and, using wireless communication, shows the end user consumption on a real-time basis, monitored or controlled through mobile or internet - so it saves both electricity and money. Common mistake: writing that the lux meter reads LUMENS. Lumen is the light OUTPUT of a lamp; lux is the light FALLING on a surface (1 lux = 1 lumen per square metre).
Source: Book/Concept
📖 §4.13 BEE (manner and intervals of time for conduct of energy audit) Regulations, 2008 — intervals of time

60. As per the BEE (manner and intervals of energy audit) Regulations 2008, what are the intervals for conducting an energy audit by a designated consumer?

Model answer: Every designated consumer must have its first energy audit conducted by an accredited energy auditor within 18 months of the notification issued by the Central Government. The interval for conduct and completion of subsequent energy audits is three years, with effect from the date of submission of the previous energy audit report by the accredited energy auditor to the management of the designated consumer.
Only two numbers matter here, so lead with them: FIRST audit within 18 MONTHS of the Central Government notification; SUBSEQUENT audits every 3 YEARS. Say what the three years is counted from - the date the previous audit report was SUBMITTED by the accredited energy auditor to the management of the designated consumer, not from the date the audit started. The audit must be by an ACCREDITED energy auditor; an in-house energy manager cannot do it. Common mistake: writing 18 months for both, or counting the three years from the notification date.
Source: Book/Concept
📖 §4.13 BEE Regulations 2008 — manner of energy audit

61. Outline the manner (steps) of conducting an energy audit as per the BEE Regulations 2008.

Model answer: The regulations prescribe: (1) Verification of energy-use data — verify the information submitted for the previous two years, establish the specific energy consumption, and disaggregate consumption to identify major energy-using equipment, processes and systems. (2) Scope of energy audit — the accredited auditor jointly with the energy manager develops the scope, selects energy-intensive equipment/processes, agrees on best-practice measurement procedures, and collects consumption, production and operating data. (3) Monitoring and analysis — verify data accuracy, analyse for consistency, give recommendations to reduce consumption, and summarise consumption by fuel type and section. Recommendations with cost-benefit analysis are then prepared and prioritised into an action plan, and the report is certified by the accredited energy auditor.
Answer as numbered steps in the order the regulation prints them - the sequence is being marked. Memory hook: VERIFY the past two years' data and establish specific energy consumption -> agree the SCOPE jointly with the energy manager (select energy-intensive equipment and processes) -> MEASURE and analyse -> RECOMMEND with cost-benefit and an implementation plan -> REPORT with the auditor's certification. The phrase to include: disaggregate consumption to identify major energy-using equipment, processes and systems. Common mistake: writing the generic ten-step audit methodology of §4.4 instead. This question is about the 2008 Regulations specifically.
Source: Book/Concept
📖 §4.13 BEE Regulations 2008 — structure of the energy audit report / certification

62. What certification must the accredited energy auditor provide in the energy audit report under the 2008 Regulations?

Model answer: The report must conclude with the accredited energy auditor's certification stating that: (a) data collection has been carried out diligently and truthfully; (b) all data-monitoring devices are in good working condition and have been calibrated/certified by approved agencies with no tampering; (c) all reasonable professional skill, care and diligence have been taken and the contents are a true representation of facts; (d) adequate training has been provided to personnel involved in daily operations after implementation; and (e) the audit has been carried out in accordance with the BEE (manner and intervals of energy audit) Regulations, 2008. The report is signed under the firm's seal with accreditation and manpower details and a signed work-schedule sheet.
Three certifications - write them as (a), (b), (c). Each is a separate mark. Memory hook: HONEST DATA (collected diligently and truthfully) - GOOD INSTRUMENTS (monitoring devices in working order, calibrated and certified by approved agencies, no tampering) - PROFESSIONAL CARE (reasonable skill, care and diligence; contents are a true representation of facts). Note who signs it: the ACCREDITED energy auditor, and the certification comes at the END of the report. Common mistake: describing the contents of the report instead of the certification clauses.
Source: Book/Concept
📖 §4.6 External benchmarking factors and benchmark parameters

63. (a) Name three factors influencing external energy benchmarking. (b) List two energy benchmarking parameters.

Model answer: (a) External-benchmarking factors (any three): scale of operation; vintage of technology; raw material specification and quality; product specification and quality. (b) Benchmarking parameters (any two, all forms of specific energy consumption): kWh/MT of cement or clinker (cement plant); kWh/kg of yarn (textile); kcal/kWh heat rate (power plant); kW/TR (air-conditioning plant); % thermal efficiency (boiler).
Read the marks: it says name THREE and list TWO. Give exactly that, then stop - extra items waste time and earn nothing. The four external-benchmarking factors to pick three from: scale of operation, vintage of technology, raw material specification and quality, product specification and quality. Energy PRICE is not one of them. For part (b), any benchmark parameter is a specific energy consumption - always write it as a RATIO with units (kWh/MT cement, kWh/kg yarn, kcal/kWh heat rate, kW/TR, % boiler efficiency). Common mistake: giving a bare number or a total consumption figure with no denominator.
Source: Mar 2023 (23rd Exam)
📖 §4.1 Definition and Objectives of Energy Management (Book EOC Objective Q1 & Q3)

64. The phrase "the judicious and effective use of energy to maximise profits and enhance competitive positions" defines which term, and what does its objective include?

Model answer: This phrase defines Energy Management (not energy conservation, energy policy or energy audit). The objective of energy management includes all of: minimising energy costs, minimising waste, and minimising environmental degradation — i.e. achieving and maintaining optimum energy procurement and utilisation while not affecting production and quality.
The quoted phrase belongs to ENERGY MANAGEMENT. Recognise it by the words "profits" and "competitive positions" - those are management words, not conservation or audit words. For the objective part, the answer is ALL of them together: minimise cost, minimise waste, minimise environmental degradation. If "all of the above" is an option, that is the answer. Memory hook: energy CONSERVATION = use less; energy AUDIT = measure and report; energy MANAGEMENT = the overall strategy that includes both. Common mistake: picking energy conservation because the phrase mentions saving.
Source: Book/Concept
📖 §4.1 Energy management function — role of the energy manager (Book EOC Objective Q2)

65. What is the role of the energy manager?

Model answer: The energy manager acts as the intermediate player between the top management and the energy/cost centres of the plant. He is responsible for driving the energy management programme — coordinating energy procurement and utilisation, monitoring energy performance, and ensuring that the conservation measures identified are implemented, while keeping management informed and involving every employee day-to-day.
The one phrase the examiner wants: the energy manager is the INTERMEDIATE PLAYER between top management and the energy/cost centres of the plant. Then give three duties: coordinate energy procurement and utilisation, monitor energy performance, and ensure the identified conservation measures are actually implemented. Add the two-way role: keeps management informed and involves employees at every level day to day. Common mistake: describing the energy AUDITOR's job. The auditor investigates and reports; the manager runs the programme continuously.
Source: Book/Concept
📖 §4.1/§4.6 energy unit equivalence (Book EOC Objective Q5)

66. One unit (kWh) of electricity is equivalent to how many kcal of heat?

Model answer: One unit (1 kWh) of electricity is equivalent to 860 kcal of heat. This conversion (1 kWh = 860 kcal) is the basis used when comparing electrical and thermal energy consumption in audits and benchmarking (e.g. heat rate in kcal/kWh).
One number to lock in: 1 kWh = 860 kcal. Learn it alongside 1 kWh = 3.6 MJ and 1 MTOE = 10^7 kcal. Where it is used: converting electricity to heat units so electrical and thermal energy can be added on one scale - in energy balances, MTOE calculations and heat rate in kcal/kWh. Memory hook: 860 comes from 3600 kJ divided by 4.1868 kJ/kcal. Common mistake: writing 3600 or 4.18. Those are the joule conversions, not the kcal equivalent of a unit of electricity.
Source: Book/Concept
📖 §4.4 Step 6 Analysis of energy use / energy balance (Sankey detail in Book-1 Ch5 & Ch9)

67. What is a Sankey diagram and how is it used in energy management?

Model answer: A Sankey diagram is a flow diagram that visualises energy flows and losses through a system, in which the width of each band/arrow is proportional to the quantity of energy it represents. It is used to depict the input energy and how it splits into useful output and the various losses, making it easy to see where the largest energy losses occur and where conservation effort should be focused.
The defining feature is the WIDTH: each band is drawn proportional to the quantity of energy it carries, so the biggest loss is visually the widest band. Say what it shows - total input splitting into useful output plus each named loss - and why it helps: it points straight at where conservation effort will pay most. In Ch4 it belongs to Step 6 (analysis of energy use / energy balance). The detailed Sankey drawing and worked examples are Book-1 Ch5 and Ch9, so revise the diagram itself there. Common mistake: drawing all arrows the same width - then it is just a block diagram, not a Sankey.
Source: Concept (supplementary)
📖 §4.1 Energy management (EnMS / ISO 50001; detail in Book-1 Ch6)

68. What is an Energy Management System (EnMS) and on what cycle does it operate?

Model answer: An Energy Management System (EnMS, e.g. ISO 50001) is a structured framework to systematically manage energy use so as to continually improve energy performance. It is driven by an energy policy and a Goal → Objective → Target hierarchy, and operates on the PDCA cycle: Plan – Do – Check – Act. This continual-improvement cycle matches the book's cyclic process of analysis → action → monitoring, where results are reviewed and new objectives set if gaps remain.
Two things must appear: the PURPOSE (a structured framework to manage energy and continually improve energy performance) and the CYCLE (PDCA - Plan, Do, Check, Act). Also give the hierarchy: energy POLICY, then Goal -> Objective -> Target. Policy first, targets last. This is really Book-1 Ch6 (ISO 50001 / energy management systems) material sitting inside Ch4, so revise the full EnMS clauses there - Ch4 only links it to the cyclic analysis-action-monitoring idea. Common mistake: writing PDCA without saying what continual improvement means in practice - results are reviewed and fed back so the next cycle sets tighter targets.
Source: Concept (supplementary)
📖 §4.6 Benchmarking — internal (historical best) vs external (inter-unit) benchmarking

69. Differentiate between internal and external energy benchmarking.

Model answer: External benchmarking is inter-unit comparison across a group of similar units (or plants within a sector) to identify best practices; it requires care in ascertaining similarities (scale, vintage, raw material and product specifications), and proprietary data is a concern so indicators must stay general. Internal benchmarking is done by a company against its own historical best performance, setting targets to reduce energy use by certain percentages over time; since it is done internally, the company need not reveal any proprietary information.
Answer in two columns; the contrast is the whole answer. Memory hook: INTERNAL = against MYSELF (the plant's own historical best performance). EXTERNAL = against OTHERS (inter-unit comparison across similar plants to find best practice). For external, add the caution: check scale, vintage of technology, raw material and product specifications before comparing, and keep indicators general because plant data is proprietary. Common mistake: saying internal benchmarking compares departments within a plant only. The book's point is comparison against the company's own best past performance, used to set reduction targets.
Source: Book/Concept
📖 §4.12 Energy audit instruments + energy-power basics (1 kWh = 3.6 MJ = 860 kcal)

70. (a) State the parameters measured by: Stroboscope, Sling Psychrometer, Fyrite, Pitot Tube. (b) An electric resistive heater consumes 3.6 MJ in one hour on a 200 V supply. Find its rating and the current drawn.

Model answer: (a) Stroboscope — non-contact speed/RPM; Sling Psychrometer — dry-bulb and wet-bulb temperature; Fyrite — O₂ and CO₂ in flue gas; Pitot tube — pressure/velocity of gas in ducts. (b) Power = Energy/time = 3.6×10⁶ J / 3600 s = 1000 W = 1 kW. Current = Power/Voltage = 1000/200 = 5 A.
Two unrelated parts - do them separately and label them (a) and (b). For (a), one line per instrument, parameter only. The traps: stroboscope is NON-CONTACT speed (tachometer is the contact one); Fyrite reads O2/CO2 only, never CO; the psychrometer gives TWO temperatures, dry bulb and wet bulb. For (b), convert first: 3.6 MJ in one hour is exactly 1 kWh, so the rating is 1 kW. Then I = P/V = 1000/200 = 5 A (a resistive heater, so power factor is 1 and P = VI applies directly). Common mistake: dividing 3.6 x 10^6 by 60 instead of 3600. Always convert the hour to seconds.
Source: Sep 2024 (24th Exam)
📖 §4.4 Step 8 Cost benefit analysis / §4.8 Matching energy usage to requirement (VSD retrofit)

71. A centrifugal pump (30 kW motor) runs 16 h/day, 300 days/yr at 65% loading and 88% efficiency with no flow control. A VFD retrofit (cost ₹1,50,000) is expected to cut energy by 10%; power cost ₹7.0/kWh. Find (a) current annual energy, (b) annual saving, (c) annual cost saving, (d) simple payback.

Model answer: (a) Current annual energy = (30 × 0.65 / 0.88) × 16 × 300 ≈ 106,364 kWh. (b) Energy saved with VFD = 106,364 × 0.10 ≈ 10,636 kWh/yr. (c) Annual cost saving = 10,636 × ₹7.0 ≈ ₹74,455. (d) Simple payback = 1,50,000 / 74,455 ≈ 2.01 years (≈ 24 months).
Work in a fixed order and show each line: input power -> annual energy -> energy saved -> money saved -> payback. Each step carries marks even if a later number is wrong. Input power = rated kW x loading / efficiency. Loading is multiplied, efficiency is DIVIDED - swapping them is the commonest error in this question type. Annual hours = hours/day x days/year (16 x 300 = 4800 h). Do not use 8760 unless the question says continuous running. Simple payback (years) = Investment / Annual cost saving. Quote it in years and, if asked, x12 for months. This is §4.4 Step 8 cost-benefit applied to a §4.8 matching-energy-to-requirement measure.
Source: Sep 2025 (25th Exam)
📖 §4.5 Understanding Energy Costs / energy accounting in MTOE (designated-consumer threshold from EC Act 2001 — Book-1 Ch2)

72. A paper plant's daily energy: 50,000 kWh total (20,000 kWh own back-pressure cogeneration, rest from grid), 100 t imported coal (GCV 6900 kcal/kg) for cogeneration, and 2 kL HSD (49574.08 kJ/kg; density 0.8263 kg/L) for material handling. (a) Daily % share of energy sources in MTOE. (b) Annual MTOE. (c) Does it qualify as a designated consumer?

Model answer: Basis: 1 MTOE (metric tonne of oil equivalent) = 10^7 kcal; 1 kWh = 860 kcal. (a) Net grid import = 50,000 - 20,000 = 30,000 kWh/day = 30,000 x 860 = 2.58 x 10^7 kcal = 2.58 MTOE. Coal for cogeneration = 100 t = 1,00,000 kg x 6900 kcal/kg = 6.9 x 10^8 kcal = 69.0 MTOE. HSD = 2 kL x 0.8263 kg/L x 1000 = 1652.6 kg; GCV = 49,574.08 kJ/kg / 4.1868 = 11,841 kcal/kg -> 1652.6 x 11,841 = 1.957 x 10^7 kcal = 1.96 MTOE. Daily total = 2.58 + 69.0 + 1.96 = 73.54 MTOE. Share: grid electricity 3.5%, coal 93.8%, HSD 2.7%. (b) Annual (365 days) = 73.54 x 365 = 26,842 MTOE (at 300 working days it would be about 22,062 MTOE). (c) The notification threshold for the pulp and paper sector is 30,000 MTOE per year. Since the annual consumption (about 26,842 MTOE, and lower still on a 300-day basis) is below 30,000 MTOE, the plant does NOT qualify to be notified as a designated consumer. (Designated-consumer thresholds come from the EC Act 2001 - Book-1 Ch2 - while the energy accounting method is Ch4 audit practice.)
Set the two conversion constants down before you calculate anything: 1 MTOE = 10^7 kcal and 1 kWh = 860 kcal. For fuels, kJ/kg divided by 4.1868 gives kcal/kg. The trap is double counting: only the NET GRID IMPORT is counted as purchased electricity, because the coal burnt in the cogeneration plant is already counted as coal. Counting all 50,000 kWh plus the coal counts the same energy twice. For HSD, convert kilolitres to kg using the density first, then apply the calorific value. Then get the daily percentage share, multiply by the operating days for the annual figure, and compare with the notified threshold for that sector. The designated-consumer threshold itself is EC Act 2001 material from Book-1 Ch2 - revise the sector-wise threshold table there, not in Ch4.
Source: Mar 2023 (23rd Exam)

Long questions (10 marks) — 16

📖 Book-1 §4.4 — Detailed Energy Audit: three phases and Ten Steps Methodology

1. Describe in detail the methodology for conducting a detailed energy audit, covering the three phases and the ten-step approach.

Model answer: A detailed (comprehensive) energy audit accounts for the energy use of all major equipment and is carried out in THREE PHASES using a flexible TEN-STEP methodology. PHASE I - PRE-AUDIT PHASE (planning): Step 1 - Plan and organise: constitute the energy audit team, do a walk-through audit, organise instruments and time frame, collect macro data suitable to the industry, hold an informal interview with the energy/production/plant manager and familiarise with the process. Step 2 - Introductory meeting with all divisional heads and persons concerned (1-2 hrs) to build cooperation and rapport, create awareness/orientation and issue questionnaires tailored to each department. PHASE II - AUDIT PHASE (measurement and analysis): Step 3 - Primary data gathering: prepare process flow diagrams and energy-utility diagrams, collect historic data to set the baseline, single-line power distribution / water / steam / compressed-air diagrams, design and operating data and the annual energy bill. Step 4 - Conduct survey and monitoring: motor, insulation and lighting surveys using portable instruments; confirm and compare operating data with design data. Step 5 - Conduct detailed trials/tests on selected major equipment: 24-hour power monitoring (MD, PF, kWh), load-variation trends in pumps/fans/compressors, boiler efficiency trials (4-8 hrs), furnace efficiency trials, equipment performance tests. Step 6 - Analysis of energy use: energy and material balance and energy loss/waste analysis. Step 7 - Identification and development of Energy Conservation (ENCON) opportunities by brainstorming, value analysis, reviewing ideas from unit personnel and previous reports, and contacting vendors. Step 8 - Cost-benefit analysis: assess technical feasibility and economic viability, prioritise ENCON options (low/medium/long term) and select the most promising projects. Step 9 - Reporting and presentation to top management, with final report prepared on feedback. PHASE III - POST-AUDIT PHASE (action): Step 10 - Implementation and follow-up: implement ENCON recommendations, prepare the action plan and schedule, monitor performance and carry out periodic review. The methodology is flexible and can be adapted to the industry concerned.
High-frequency long question. Remember the phase split: Pre-Audit = Steps 1-2, Audit = Steps 3-9, Post-Audit = Step 10. Anchor each step by its one-line purpose. The energy/material balance (Step 6) is a key element of any detailed audit.
Source: unknown
📖 Book-1 §4.12 — Instruments and Metering for Energy Audit

2. Describe the common instruments used in an energy audit and state the parameter each one measures.

Model answer: Energy audit instruments are portable, durable, easy to operate and relatively inexpensive. 1. Electrical measuring instruments (power/PF analyzers): measure kVA, kW, PF, Hz, kVAr, amps, volts and (advanced units) harmonics. Applied on-line on running motors without stopping them; hand-held meters give instant readings, advanced ones give cumulative printouts. 2. Fyrite: draws a flue-gas sample by a hand-bellows pump into a chemical solution; a colour/volume change gives the gas percentage. Reads O2 or CO2 in flue gas using the Orsat method - KOH (dyed red) absorbs CO2, chromous chloride (blue) absorbs O2; the absorbing fluid is also the indicating fluid. 3. Fuel efficiency monitor: measures oxygen and temperature of the flue gas; calorific values fed to a microprocessor which computes combustion efficiency. 4. Combustion gas analyzer: in-built chemical cells/sensors measure CO2, CO, NOx, SOx etc.; sensors are interchangeable but only two-three parameters can be read at a time; lighter than the fuel efficiency monitor. 5. Manometer with pitot tube: a digital flexible-membrane manometer used with a pitot tube to measure velocity/pressure of exhaust flue gases in ducts (boilers, furnaces) or air from fans and blowers (a 6-cm hole is made in the duct). 6. Contact thermometer: thermocouples that measure flue-gas, hot-air and hot-water temperatures by inserting a probe into the stream; a leaf-type probe measures surface temperature. 7. Non-contact infrared thermometer: calculates surface temperature from the infrared radiation emitted by an object (emissivity must be known); ideal for hazardous or hard-to-reach places. 8. Ultrasonic flow meter: non-contact liquid flow measurement. Transit-time type sends signals with and against flow and uses the time difference (clean liquids); Doppler type uses frequency shift from particles (dirty liquids). 9. Speed measurement: tachometer (contact type, where direct access is possible) and stroboscope (non-contact; high-intensity light flashes at a precise frequency make periodic motion appear slowed/stopped to read RPM). 10. Sling psychrometer: dry-bulb and wet-bulb thermometers whirled around; evaporation cools the wet bulb, and the two readings give humidity. 11. Lux meter: a light-sensitive cell measures incident visible light against the human daylight-sensitivity curve, giving illumination in lux. 12. Smart energy meter: gives real-time electricity (or fuel/water) usage via wireless communication; monitored/controlled through mobile or internet. 13. Thermography (thermal imaging camera): non-contact; converts radiated IR energy into a video image showing hot/cold spots for predictive maintenance.
The single highest-yield topic in Ch.4. Learn the instrument-to-parameter map cold. Trick pairs: Fyrite = O2/CO2 flue gas (NOT SOx); Stroboscope = non-contact RPM vs Tachometer = contact; Ultrasonic transit-time = clean liquid, Doppler = dirty; Pitot+manometer = duct air/gas velocity.
Source: unknown
📖 Book-1 §4.1 — Definition and Objectives of Energy Management

3. Define energy management. State its fundamental goal, objectives and the essentials for successful energy management.

Model answer: Definition: Energy management is 'the judicious and effective use of energy to maximise profits (minimise costs) and enhance competitive positions'. Alternatively, it is 'the strategy of adjusting and optimising energy, using systems and procedures so as to reduce energy requirements per unit of output while holding constant or reducing total costs of producing that output'. Fundamental goal: to produce goods and provide services with the LEAST COST and LEAST ENVIRONMENTAL EFFECT. Objectives of energy management: 1. To achieve and maintain optimum energy procurement and utilisation throughout the organization. 2. To minimise energy costs / waste without affecting production and quality. 3. To minimise environmental effects (degradation). Essentials for success: Successful energy management must combine an effective strategy with the right practical action. It begins with the key decision makers and then involves every employee on a day-to-day basis. Many organisations wish to save energy, but to achieve the greatest impact they must give priority to energy management and make it an integral part of the company's overall management strategy.
The famous quoted definition is a guaranteed 1-mark and the anchor of any essay answer. The three objectives are commonly examined as 'all of the above'. Note the goal is stated as least cost AND least environmental effect.
Source: unknown
📖 Book-1 §4.4 — Types of Energy Audit and Approach

4. Explain the different types of energy audit. Bring out the major differences between a preliminary energy audit and a detailed energy audit.

Model answer: The type of energy audit depends on the type of industry, the depth required and the magnitude of cost reduction desired. There are THREE types: 1. Preliminary energy audit (also Walk-through / Diagnostic audit): a relatively quick exercise using existing or easily-obtained data. Its scope is to establish energy consumption in the organization (from energy bills/invoices), obtain production data to relate to energy use, estimate the scope for savings, identify the easiest areas for attention (e.g. unnecessary lighting, high temperature settings, leakage), identify immediate no-/low-cost improvements, set up a baseline/reference point and identify areas for more detailed study. 2. Targeted energy audit: often results from a preliminary audit; provides detailed data and analysis on a specified target (e.g. the lighting, boiler, steam or compressed-air system). It involves a detailed survey of the target subject, analysis of the associated energy flows and costs, and recommendations on actions to be taken. 3. Detailed (comprehensive) energy audit: accounts for the energy use of all major equipment and results in a detailed energy project implementation plan. It considers the interactive effects of various projects, offers the most accurate estimate of energy savings and cost, and includes detailed cost-saving and project-cost calculations. A key element is the energy balance, based on an inventory of energy-using systems, current operating assumptions, and measurements/calculations of energy use. Major differences (Preliminary vs Detailed): (a) Data - preliminary uses existing/easily obtained data, detailed uses measured data from surveys and trials; (b) Depth - preliminary is quick and identifies easy/no-cost measures and a baseline, detailed covers all major equipment with an energy balance; (c) Accuracy - detailed gives the most accurate savings and cost estimates and considers interactive effects; (d) Output - preliminary flags areas for study, detailed delivers a full project implementation plan with calculations and payback.
Common 5-10 mark question. Preliminary = quick, existing data, baseline + easy savings; Detailed = all equipment, energy balance, accurate costs, implementation plan. Targeted sits in between and focuses on ONE system.
Source: unknown
📖 Book-1 §4.6 — Benchmarking

5. What is energy benchmarking? Explain its approaches, the metric used, external benchmarking factors, and give examples of benchmark (specific energy consumption) parameters.

Model answer: Energy benchmarking is a process in which the energy performance of an individual plant or an entire sector of similar plants is compared against a common metric that represents 'standard' or 'optimal' performance; it may also compare the performance of several plants against each other. Benchmarking forms the basis for monitoring and target setting. Metric: Because benchmarks are applied to plants of different sizes and outputs, the metric must be common irrespective of plant size. The most common metric is ENERGY INTENSITY = energy use per unit of output, applied over a wide range of facilities. Three approaches: (1) Evaluate an entire industrial sector (e.g. iron & steel, cement, aluminium) against best available technology and against the same sector in other countries. (2) External benchmarking - compare individual plants within a sector on even terms to identify best practices (proprietary-data concerns arise). (3) Internal benchmarking - large companies set goals using their own historical best performance; no proprietary information need be disclosed. External benchmarking comparative factors that must be examined (else findings mislead): scale of operation, vintage of technology, raw material specification & quality, and product specification & quality. (Energy PRICE is NOT one of these factors.) Examples of benchmark parameters (specific energy consumption): kWh/MT clinker or cement (cement plant); kWh/kg yarn (textile); kWh/MT or kcal/kg paper (paper plant); kcal/kWh = heat rate (power plant); Million kcal/MT urea or ammonia (fertilizer); kWh/MT liquid metal (foundry); kWh/TR (air-conditioning plant); % thermal efficiency of a boiler; % cooling-tower effectiveness; kWh/Nm3 of compressed air; kWh/litre in a diesel power plant.
The four external-benchmarking factors (scale, vintage, raw material, product) are a classic 5-marker, and 'energy price is NOT a factor' is a trick objective. Energy intensity (energy per unit output) is the key size-independent metric.
Source: unknown
📖 §4.7 Solved Example — Plant Energy Performance

6. An Energy Manager gathered the following data: Reference Year (2009) energy use = 12 million kcal; Production Factor for the current year (2010) = 0.9; Current year's energy = 11 million kcal. Compute the Plant Energy Performance (PEP) for 2010 and state your inference.

Model answer: Step 1 - Reference Year Equivalent energy use = Reference year energy use x Production Factor = 12 x 0.9 = 10.8 Mkcal. (This is the energy that would have been needed to make the current year's output if the plant ran as it did in the reference year.) Step 2 - Plant Energy Performance: PEP (%) = [(Reference Year Equivalent - Current year's energy) / Reference Year Equivalent] x 100 PEP = [(10.8 - 11) / 10.8] x 100 PEP = (-0.2 / 10.8) x 100 = -1.85%. Inference: The plant energy performance is marginally NEGATIVE (-1.85%), meaning the plant used slightly more energy than the reference-year rate for the same output - a small deterioration. The energy manager / plant manager must take corrective action to improve performance. (A positive PEP would indicate improvement; the greater the number, the greater the energy saved.)
The book's solved example. Sequence: Production Factor -> Reference Year Equivalent (ref energy x PF) -> PEP% = (RYE - current)/RYE x 100. Positive = improvement, negative = deterioration.
Source: unknown
📖 §4.7 Production Factor, Reference Year Equivalent and Plant Energy Performance (Book EOC Long Q L-1)

7. Explain the following: (i) Production factor (ii) Reference Year Equivalent (iii) Plant Energy Performance.

Model answer: (i) Production factor: the ratio of the production in the current year to the production in the reference (base) year. Production factor = Current year's production / Reference year's production. It is used to determine the energy that would have been required to produce the current year's output if the plant had operated as it did in the reference year. (ii) Reference Year Equivalent (reference year equivalent energy use): the energy that would have been used to produce the current year's production output, obtained by multiplying the reference year's energy use by the production factor. Reference year equivalent = Reference year energy use x Production factor. (iii) Plant Energy Performance (PEP): a measure of whether a plant is now using more or less energy to manufacture its products than it did in the past - i.e. how well the energy management programme is doing. It is the improvement or deterioration from the reference year: PEP (%) = [(Reference year equivalent - Current year's energy) / Reference year equivalent] x 100. The greater the improvement, the higher (more positive) the number; yearly comparisons minimise seasonal effects. PEP is the starting point for evaluating energy performance and can be used for monthly as well as yearly reporting.
This is the verbatim end-of-chapter Long Question L-1. Keep the three formulae exact and in sequence; they lead directly into any PEP numerical.
Source: unknown
📖 §4.12 Energy audit instruments — Psychrometer, Infrared thermometer, Stroboscope, Pitot tube (Book EOC Long Q L-2)

8. Write short notes on: (i) Psychrometer (ii) Infrared thermometer (iii) Stroboscope (iv) Pitot tube.

Model answer: (i) Psychrometer: a sling psychrometer consists of two thermometers mounted with a handle - one ordinary (dry-bulb) thermometer measuring air temperature, and one with a wet cloth wick (wet-bulb). When whirled around, water evaporates from the wick and cools the wet-bulb thermometer; drier air causes more evaporation and a larger difference between the two readings. From the dry-bulb and wet-bulb temperatures the humidity (moisture content / relative humidity) of the air is computed. (ii) Infrared (non-contact) thermometer: calculates the amount of thermal (infrared) radiation emitted by an object; knowing the object's emissivity and the emitted IR energy, its surface temperature is determined. A lens focuses the IR energy onto a detector that converts it into an electrical signal displayed as temperature (after ambient-temperature correction). It is used for objects in hazardous or hard-to-reach places. (iii) Stroboscope: a non-contact speed (RPM) measuring instrument. A stroboscopic light source gives high-intensity flashes of light at a precise, adjustable frequency; when this light falls on an object in periodic motion, the motion appears slowed or stationary when the flash frequency and the rotational frequency bear a definite relationship - allowing the RPM to be read. (iv) Pitot tube: used with a (flexible-membrane) manometer to measure velocity/pressure in air ducts carrying exhaust flue gases (boilers, furnaces) or air from fans and blowers. Flexible tubes connect the manometer to the pitot tube, which is inserted through a ~6-cm hole in the duct; from the pressure difference the air/gas velocity, and hence flow, is obtained.
The verbatim end-of-chapter Long Question L-2. Each note: state the instrument, the parameter it measures, and one line on the working principle. Psychrometer -> humidity; IR -> surface temp (non-contact); Stroboscope -> RPM (non-contact); Pitot -> duct air/gas velocity.
Source: unknown
📖 Book-1 §4.4 — Identification of ENCON Opportunities; Technical and Economic Feasibility; Classification of ENCON Measures (Table 4.1)

9. How are Energy Conservation (ENCON) opportunities identified and evaluated in a detailed energy audit? Explain their technical/economic feasibility and how ENCON measures are classified and prioritised.

Model answer: Identification of ENCON opportunities: (a) Fuel substitution - identifying the appropriate fuel for efficient energy conversion. (b) Energy generation - efficiency opportunities in conversion equipment/utilities, e.g. high-efficiency DG sets, optimal DG loading, boiler optimisation (minimum excess-air combustion), biomass gasifiers, cogeneration. (c) Energy distribution - efficiency in transformers, cables, switchgear, power-factor improvement, and in chilled/cooling/hot water and compressed air. (d) Energy usage by processes - the biggest, often hidden opportunity; process analysis/integration is a useful tool. Technical feasibility should address: technology availability, space and skilled manpower; impact of the measure on safety, quality, production or process; and reliability, service, maintenance requirements and spares availability. Economic viability is usually the key parameter for management acceptance, analysed by payback method, IRR or NPV. For low-investment, short-duration measures with attractive returns, the simple payback method suffices: Net savings/year = Annual savings - Annual operating costs; Payback period (months) = (Investment / Net savings per year) x 12. Classification of ENCON measures (three categories): (a) Low cost - high return; (b) Medium cost - medium return; (c) High cost - high return. Normally the LOW cost - high return projects receive priority. Projects involving equipment/process changes usually carry high cost and high returns and need careful scrutiny and long lead times. Prioritisation for implementation: A - No investment (immediate: operational improvement, housekeeping); B - Low investment (short-to-medium term: controls, equipment modification, process change); C - High investment (long term: energy-efficient devices, product modification, technology change). Project priority is also judged on economic feasibility, technical feasibility and risk (grades A-good/highly feasible, B-may be, C-held, D-no).
Covers Steps 7-8 of the audit. Anchor the four ENCON areas (generation, distribution, process usage, fuel substitution), the payback formula, and the two classifications: cost-return (low/medium/high) and implementation priority (A no-invest / B low / C high).
Source: unknown
📖 §4.11 Fuel and Energy Substitution — Case Study on fuel substitution

10. Explain fuel substitution and energy substitution with examples, and illustrate the economics with a case study of replacing a furnace-oil thermic fluid heater by an agro-fuel fired heater.

Model answer: Fuel substitution is basically substituting an existing fossil fuel with a more efficient and/or less costly/less polluting fuel such as natural gas, biogas and locally available agro-residues. There are two ways to reduce energy dependency: energy conservation and substitution. Examples of FUEL substitution: - Natural gas as fuel and feedstock in fertilizer, petrochemicals, power and sponge-iron industries. - Replacement of coal by coconut shells, rice husk etc. - Replacement of LDO by LSHS. Examples of ENERGY substitution: - Replacement of electric heaters by steam heaters. - Replacement of steam-based hot water by solar systems. Case study (agro fuel in place of furnace oil): A textile process industry replaced an old furnace-oil fired thermic fluid heater with a coconut-chip (agro fuel) fired boiler. Old system: furnace oil, GCV 10,200 kcal/kg, thermal efficiency 82%, heat duty 15 lakh kcal/hr, operating 25 days x 12 months x 24 hrs = 7,200 hrs, annual fuel cost = 7,200 x Rs.1,800/hr = Rs.130 lakh. Modified system: coconut chips, GCV 4,200 kcal/kg, thermal efficiency 72%, same 15 lakh kcal/hr heat duty; annual operating cost = 7,200 x Rs.700/hr = Rs.50 lakh. Annual savings = 130 - 50 = Rs.80 lakh. Less additional auxiliary power + manpower cost = Rs.10 lakh -> Net annual saving = Rs.70 lakh. Investment for new coconut-fired heater = Rs.35 lakh. Simple payback period = 35 / 70 x 12 = 6 months. Despite the agro fuel's lower GCV and lower efficiency, its far lower cost per hour gives an attractive 6-month payback.
Distinguish fuel substitution (change the fuel) from energy substitution (change the energy form/carrier). The case shows that a cheaper fuel can win even with lower calorific value and efficiency - the deciding factor is Rs/hr operating cost. Payback = Investment/Net annual saving x 12.
Source: unknown
📖 Book-1 §4.4 — Energy Audit Report and Table of Contents

11. Describe the structure and contents of a detailed energy audit report.

Model answer: The length and detail of the report depend on the facility audited, but it should be written in a clear, concise and easy-to-understand style so the reader is more likely to implement the recommendations. It should begin with an EXECUTIVE SUMMARY giving management a brief synopsis of the total savings and a highlight of each energy-saving measure, tailored to non-technical personnel. The MAIN REPORT should: start with a general description of the process/facility; present annual energy consumption and bills with tables and graphs; describe energy inputs and outputs by major department or process and evaluate the efficiency of each step; then present the recommended ENCON measures with cost-benefit calculations and expected payback on any capital investment. It should conclude with specific recommendations for detailed engineering studies and feasibility analyses needed to justify high-investment measures. A typical detailed-energy-audit table of contents: (i) Acknowledgement; (ii) Energy Audit Team; (iii) Executive Summary (options at a glance and recommendations). 1.0 Introduction about the plant (general details, components of production cost, major energy use/areas). 2.0 Production process description (process, process flow diagram and major unit operations, major raw-material inputs and costs). 3.0 Energy and utility system description (list and brief description of each utility - electricity, steam, water, compressed air, chilled water, cooling water). 4.0 Detailed process flow diagram and energy & material balance (flow, temperature, pressure of streams; water balance). 5.0 Energy efficiency in utility and process systems (specific energy consumption; boiler, thermic-fluid heater, furnace, cooling-water, DG set, refrigeration, compressed-air, motor-load and lighting assessments). 6.0 Energy conservation options and recommendations (list by no/low/medium/high cost, annual savings, payback; implementation plan). Annexures: list of instruments, list of vendors and other technical details.
Two-part answer: the writing principles (executive summary for management + technical main report) AND the standard table of contents (sections 1.0-6.0 plus annexures). Reporting formats include Table 4.2 (summary of savings) and Table 4.4 (recommendation format).
Source: unknown
📖 Book-1 §4.13 — BEE (Manner and Intervals of Time for Conduct of Energy Audit) Regulations, 2008

12. Under the BEE (Manner and Intervals of Time for Conduct of Energy Audit) Regulations, 2008, state the intervals for conducting energy audits and describe the manner in which an accredited energy auditor conducts the audit and prepares the report.

Model answer: Intervals of time: (1) Every designated consumer shall have its FIRST energy audit conducted by an accredited energy auditor within 18 MONTHS of the notification issued by the Central Government. (2) The interval for subsequent energy audits shall be every THREE YEARS from the date of submission of the previous audit report by the accredited energy auditor to the management of the designated consumer. Manner of energy audit (duties of the accredited auditor): 1. Verification of data of energy use - verify the information submitted under the 2007 Rules for the previous two years, establish specific energy consumption for that year, and disaggregate the data to identify major energy-using equipment, processes and systems. 2. Scope of energy audit - jointly with the energy manager, develop a scope of work ensuring adequate coverage of total energy use, select energy-intensive equipment/processes, agree best-practice measurement procedures, and collect energy, production, operating and schedule data and non-proprietary process flow charts. 3. Monitoring and analysis - verify accuracy of collected data, analyse consistency, give recommendations to reduce consumption and improve efficiency, provide a summary of consumption by fuel type and section, and conduct equipment performance measurements with due diligence. 4. Recommendations and cost-benefit analysis - prepare a list of measures each with a brief description, estimated energy saving and cost-reduction potential over its life, known technical risks, a preliminary financial-attractiveness assessment, a tabulated summary by implementation schedule (short/medium/long term), examination of alternatives, and discussion of impacts on operation/maintenance/staffing/budget. 5. Prioritisation and action plan - jointly with the energy manager, select technically viable and financially attractive measures within the consumer's means, prioritise them, prepare a detailed techno-economic analysis, a monitoring & verification protocol, and an agreed time schedule; submit the report in Form 2 and evaluate previous-audit implementation in Form 3. Report structure & certification: the report is jointly decided by auditor and consumer, highlights specific energy consumption and recommendations, and concludes with the auditor's certification that data collection was diligent and truthful, all monitoring devices were calibrated/certified and untampered, professional skill and care were used, adequate training was provided, and the audit complied with the 2008 Regulations. The auditor also highlights strengths/weaknesses in energy management, signs under the firm's seal with accreditation and manpower details, and includes a signed work-schedule sheet.
Two headline numbers: first audit within 18 months, then every 3 years. The 'manner' follows a logical chain: verify data -> define scope -> monitor & analyse -> recommend with cost-benefit -> prioritise & action plan -> certified report. Certification points are commonly asked.
Source: unknown
📖 Book-1 §4.4 — Phase I: Pre-Audit Phase (initial site visit)

13. What are the areas to be focused on during the pre-audit phase of a detailed energy audit? Describe the actions of the energy auditor during the initial site visit.

Model answer: Proper planning is a pre-requisite for an effective audit, so an initial site study is always carried out. An initial site visit should take about one day and lets the energy auditor meet the concerned personnel, familiarise with the site, and assess the procedures needed for the audit. During the initial site visit the energy auditor/engineer should: discuss with senior management the aims of the audit; explain the purpose of the audit and the kind of information needed during the facility tour; discuss economic guidelines associated with the recommendations; analyse the major energy-consumption data with the relevant personnel; obtain site drawings where available (plant/building layout, steam, compressed-air and electricity distribution); and tour the site accompanied by a site representative. For each system the auditor typically asks: what function does it serve, how does it serve it, what is its energy consumption, what indicates it is working, how can it be restored if not working, and how can its energy cost be reduced. Outcome / focus areas of the pre-audit phase: finalise the energy audit team; know management's expectations from the audit; identify the main energy-consuming areas/plant items to be surveyed; identify existing instrumentation and the additional metering required (for electricity, steam, oil or gas); plan the audit with a time frame; collect macro data on plant energy resources and major energy-consuming equipment; and build awareness and support for the detailed audit.
Covers Steps 1-2 (Phase I). The examinable list is the 'outcome of the visit' - team, management expectations, energy-consuming areas, instrumentation/metering, time plan, macro data, and awareness building. Pair it with the six diagnostic questions the auditor asks of each system.
Source: unknown
📖 Book-1 §4.3 — Need for Energy Audit; §4.5 — Understanding Energy Costs

14. Explain the need for an energy audit and discuss 'understanding energy costs', including the factors governing fuel costs and power costs.

Model answer: Need for energy audit: In any industry the three top operating costs are usually energy (electrical and thermal), labour and materials; of these, ENERGY has the highest potential for cost reduction. An energy audit helps understand how energy is used, identifies where waste occurs and where scope for improvement exists, reviews variations in energy costs, availability and reliability of supply, helps decide the appropriate energy mix, and identifies energy-conservation technologies and retrofits. In short, an energy audit translates conservation ideas into reality by evolving technically feasible solutions within economic and organizational considerations and a set time frame. Understanding energy costs: Contrary to common belief, energy cost is NOT a fixed overhead - there is often huge potential for savings. Where sufficient meters are not available, fuel and electricity invoices and the annual balance sheet are useful sources. Energy invoices provide a record/baseline of energy purchased, indicate potential savings when related to production, and can later quantify the savings achieved through conservation. Factors governing FUEL cost: fuel is purchased in tonnes or kilolitres; the three main considerations are availability, cost and quality. During procurement, account for: price at source, transport charge and type of transport; quality of fuel (contamination, moisture); and energy content (calorific value). Factors governing POWER cost: electricity price varies from state to state and consumer to consumer. Deciding factors include: maximum demand charges (kVA - how fast electricity is used); energy charges (kWh - how much is consumed); Time-of-Day (TOD) charges (peak/non-peak - when electricity is used); power-factor charges (real vs apparent power); other incentives/penalties; high-tension vs low-tension tariff; slab rates; tariff category (commercial/residential/industrial/agricultural etc.); tariffs for developed/underdeveloped areas; and tax holidays for new projects.
Two clean lists to memorise: fuel cost = price/transport + quality + calorific value; power cost = kVA (max demand) + kWh (energy) + TOD + power factor + tariff structure. Key line: energy has the highest cost-reduction potential of the three top operating costs, and energy cost is NOT a fixed overhead.
Source: unknown
📖 Book-1 §4.8 — Matching Energy Usage to Requirement; §4.9 — Maximizing System Efficiencies; §4.10 — Optimising Input Energy Requirements

15. Explain, with examples, the strategies of (a) matching energy use to requirement, (b) maximizing system efficiencies, and (c) optimizing input energy requirements.

Model answer: (a) Matching energy usage to requirement: mismatch between equipment capacity and user requirement causes inefficiency through part-load operation and wastage. Designers add safety margins, leading to oversized equipment, which the energy manager can right-size. Examples: eliminate throttling of a pump by impeller trimming, variable-speed drives (VSDs) or resizing the pump; eliminate damper operation in fans by impeller trimming, VSDs, pulley-diameter modification for belt drives or fan resizing; moderate chilled-water temperature to actual process needs; recover energy lost in control-valve pressure drops using a back-pressure turbine; and adopt task lighting in place of less-effective area lighting. (b) Maximizing system efficiencies: once usage and sources are matched, operate equipment efficiently through best O&M practices and best available technology. Examples: eliminate steam leakages using appropriate steam traps; maximise condensate recovery; adopt combustion controls for maximum combustion efficiency; replace pumps, fans, air compressors, refrigeration compressors, boilers, furnaces and heaters where significant efficiency margins exist; and ensure rated electrical parameters at the motor terminals. (c) Optimizing input energy requirements: after fine-tuning usage, minimise the input energy purchased. Measures: maximise heat recovery from waste-energy streams to reduce purchased energy; adopt cogeneration plants to balance heat and power requirements; and adopt cost-effective renewable sources such as solar, wind and biomass energy. Together these form a logical sequence - first match capacity to need, then run efficiently, then reduce the input energy that must be bought.
Book sections 4.8-4.11 as a single graded strategy. Order matters: match (right-size: impeller trim/VSD/resize) -> maximize (steam traps, condensate recovery, combustion control) -> optimize input (waste-heat recovery, cogeneration, renewables). 'Give three examples of matching energy use' is a frequent 5-marker.
Source: unknown
📖 §4.6 Benchmarking / §4.7 Energy performance — specific energy consumption and capacity assessment

16. A foundry runs an induction furnace of 5 t/hr capacity with specific electrical energy 620 kWh/t of liquid metal and casting yield 60%. A heat-treatment oil-fired furnace consumes 75 kg fuel oil per tonne of castings (GCV 10,000 kcal/kg). Auxiliary connected load 50 kW; transformer efficiency 98%; castings 45 t/day, continuous operation. (a) Find the total energy consumption per tonne of finished product as oil equivalent (kg oil/t). (b) For an additional order of 30 t/day, assess whether the plant can handle the extra demand.

Model answer: (a) Casting yield 60%, so 1 t of finished casting needs 1/0.60 = 1.667 t of liquid metal. Melting (electrical) = 620 x 1.667 = 1033.3 kWh/t finished = 1033.3 x 860 = 8,88,667 kcal/t. Auxiliaries = 50 kW x 24 h = 1200 kWh/day over 45 t/day = 26.67 kWh/t = 22,933 kcal/t. Sub-total electrical at the machine = 8,88,667 + 22,933 = 9,11,600 kcal/t; referred to the transformer input (98% efficiency) = 9,11,600 / 0.98 = 9,30,204 kcal/t. Heat treatment (oil) = 75 kg/t x 10,000 kcal/kg = 7,50,000 kcal/t. Total = 9,30,204 + 7,50,000 = 16,80,204 kcal per tonne of finished product. As oil equivalent = 16,80,204 / 10,000 = 168.0 kg of oil per tonne of finished casting. (b) The induction furnace is the bottleneck. Present liquid-metal rate = (45/24)/0.60 = 3.125 t/hr. Extra order of 30 t/day of castings = (30/24)/0.60 = 2.083 t/hr of liquid metal. Total required = 3.125 + 2.083 = 5.21 t/hr, which exceeds the 5 t/hr furnace capacity. Hence the plant CANNOT absorb the additional 30 t/day with the existing furnace; it would need extra melting capacity, or an improvement in casting yield (a yield of about 62.5% would bring the requirement back to 5 t/hr).
Book-only concepts (specific energy consumption, yield, 1 kWh = 860 kcal, oil equivalent via GCV) applied to a real exam numerical. Key steps: divide by yield to convert per-finished-tonne, convert kWh to kcal (x860), add auxiliary and transformer loss, then check the melting-furnace capacity against required liquid-metal rate. verified=false because the numerical itself is from an exam paper, not the guidebook text.
Source: unknown