Energy Auditing & Assessment Techniques Flashcards
7 cards from real CEA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Energy Auditing & Assessment Techniques flashcards as text
When conducting an energy audit on a data center, which metric is used to assess overall infrastructure energy efficiency?
Answer: Power Usage Effectiveness (PUE)
PUE = Total Facility Power ÷ IT Equipment Power; a PUE of 1.0 is ideal, meaning all energy goes to IT loads with zero overhead.
An energy auditor discovers that a chiller is operating at a COP of 2.8, while the manufacturer's rated COP at design conditions is 5.2. The MOST LIKELY cause is:
Answer: Fouled condenser tubes increasing condensing temperature and reducing heat transfer
Fouled condenser tubes raise condensing temperature, significantly degrading chiller COP; tube cleaning is a high-ROI maintenance measure.
In an industrial facility audit, 'pinch analysis' is used to:
Answer: Identify the minimum heating and cooling energy required by optimizing heat exchanger network design
Pinch analysis identifies thermodynamic limits on heat recovery and targets opportunities to maximize heat exchanger integration, reducing external heating/cooling demand.
A commercial building energy audit reveals a power factor of 0.72. What is the energy management implication?
Answer: The facility may incur utility power factor penalty charges and should add capacitor banks to correct it
Low power factor (below 0.90–0.95) causes utilities to charge penalties; capacitor banks or VFDs can correct power factor and eliminate surcharges.
During a steam system audit, an auditor uses an ultrasonic detector and finds multiple steam traps that are 'blowing through.' This indicates:
Answer: Failed-open traps that are wasting live steam, a major energy loss requiring immediate replacement
Traps that blow through are failed-open, continuously venting live steam rather than only condensate, and represent significant direct energy waste.
The ASHRAE Level III energy audit (investment-grade audit) is distinguished from Level II by:
Answer: More rigorous field measurements, sub-metering, and detailed energy modeling to reduce savings uncertainty for financing
A Level III audit provides sufficient engineering rigor (sub-metering, calibrated simulation) to justify capital investment decisions and third-party energy project financing.
When performing a combustion analysis on a natural gas boiler, an auditor measures 15% excess air and stack temperature of 450°F. The BEST immediate recommendation is to:
Answer: Tune the burner to reduce excess air to 10–15% and lower stack temperature to improve combustion efficiency
Burner tuning to optimize the fuel-air ratio and stack temperature recovery are low-cost measures that can improve boiler efficiency by 2–5 percentage points.