AFE Energy Management & Sustainability 2 — Questions and Answers
Question 1: A facilities engineer wants to benchmark a building's energy performance. Which metric is most commonly used for this purpose in the US?
- Energy Use Intensity (EUI) (Correct answer)
- Total Energy Cost Index (TECI)
- Demand Factor Ratio (DFR)
- Power Density Index (PDI)
Correct answer: Energy Use Intensity (EUI)
Energy Use Intensity (EUI) measures energy consumption per square foot per year and is the standard US benchmarking metric used by ENERGY STAR Portfolio Manager.
Question 2: Which of the following best describes a 'demand charge' on a commercial utility bill?
- A fee based on total kWh consumed during the billing period
- A charge based on the highest 15- or 30-minute peak power demand recorded (Correct answer)
- A penalty for exceeding contracted energy limits
- A surcharge applied during off-peak hours
Correct answer: A charge based on the highest 15- or 30-minute peak power demand recorded
Demand charges are billed based on the peak power draw (kW) recorded during the billing period, typically measured in 15- or 30-minute intervals.
Question 3: In an HVAC system, what does the term 'economizer cycle' refer to?
- Using waste heat from chillers to pre-heat domestic hot water
- Using outdoor air for free cooling when conditions allow (Correct answer)
- Reducing compressor speed during off-peak periods
- Cycling compressors on and off to reduce energy use
Correct answer: Using outdoor air for free cooling when conditions allow
An economizer cycle uses cool outdoor air to provide free cooling to the building, reducing or eliminating mechanical refrigeration when outdoor conditions are favorable.
Question 4: A facility manager is evaluating two lighting retrofit options. Option A has a simple payback of 2 years; Option B has a simple payback of 4 years but a higher NPV over 10 years. Which statement is most accurate?
- Option A is always the better investment because it pays back faster
- Option B may be the better long-term investment despite the longer payback (Correct answer)
- Simple payback and NPV will always agree on the best option
- Option B should be rejected because payback exceeds 3 years
Correct answer: Option B may be the better long-term investment despite the longer payback
Simple payback ignores the time value of money and post-payback savings, so a higher NPV over the project life makes Option B potentially superior for long-term financial performance.
Question 5: What is the primary purpose of an energy audit's 'baseline' energy model?
- To project future utility rate increases
- To establish current energy consumption patterns for comparing ECM savings (Correct answer)
- To document equipment nameplate data for asset management
- To calculate peak demand charges for the previous 12 months
Correct answer: To establish current energy consumption patterns for comparing ECM savings
The baseline model represents existing energy use so that the projected savings from energy conservation measures (ECMs) can be calculated as a measurable difference.
Question 6: Which refrigerant property makes R-410A unsuitable as a long-term drop-in replacement for systems being phased out under the AIM Act?
- High ozone depletion potential (ODP)
- Very high global warming potential (GWP) of approximately 2,088 (Correct answer)
- Flammability classification of A3
- Incompatibility with polyol ester (POE) oils
Correct answer: Very high global warming potential (GWP) of approximately 2,088
R-410A has a GWP of ~2,088, making it subject to phase-down under the AIM Act, which targets high-GWP HFCs to reduce climate impact.
Question 7: A compressed air system audit reveals significant pressure drop across the distribution piping. What is the most likely consequence of excessive pressure drop?
- Increased air quality at point of use
- Compressors must run at higher pressure to compensate, increasing energy consumption (Correct answer)
- Reduced maintenance frequency for end-use tools
- Lower risk of system leaks
Correct answer: Compressors must run at higher pressure to compensate, increasing energy consumption
Excessive pressure drop forces the compressor to operate at higher discharge pressures to deliver adequate pressure at end-use points, directly increasing energy consumption.
AFE Energy Management & Sustainability 2
A facilities engineer wants to benchmark a building's energy performance.
Which metric is most commonly used for this purpose in the US?