EMP Energy Efficiency & Conservation Techniques 3 — Questions and Answers
Question 1: Which building envelope measure provides the greatest energy benefit in a climate with both hot summers and cold winters?
- Installing low-emissivity (low-e) window glazing (Correct answer)
- Painting the roof white
- Adding a vestibule at the main entrance
- Replacing solid exterior doors with glass doors
Correct answer: Installing low-emissivity (low-e) window glazing
Low-e coatings reduce both solar heat gain in summer and radiant heat loss in winter, benefiting mixed climates year-round.
Question 2: A process heating system uses natural gas. The energy manager proposes heat recovery from exhaust gases. What device is typically installed for this purpose?
- Economizer coil
- Recuperator or regenerator heat exchanger (Correct answer)
- Absorption chiller
- Variable frequency drive
Correct answer: Recuperator or regenerator heat exchanger
Recuperators and regenerators transfer heat from hot exhaust gases to incoming combustion air, improving furnace efficiency.
Question 3: According to DOE guidelines, what is the recommended setpoint range for server room cooling to maximize energy efficiency without risking equipment damage?
- 55–65°F (13–18°C)
- 65–70°F (18–21°C)
- 80–95°F (27–35°C) (Correct answer)
- 45–55°F (7–13°C)
Correct answer: 80–95°F (27–35°C)
ASHRAE A1 class equipment allows inlet temperatures up to 80.6°F (27°C), and raising setpoints toward this range cuts cooling energy significantly.
Question 4: What is the primary advantage of a ground-source heat pump (GSHP) over an air-source heat pump in cold climates?
- Lower installation cost
- Access to a more stable heat source that remains above freezing (Correct answer)
- Uses no electricity at all
- Requires no maintenance
Correct answer: Access to a more stable heat source that remains above freezing
Ground temperatures remain relatively constant year-round, allowing GSHPs to maintain high efficiency even when outdoor air temperatures are very low.
Question 5: An energy manager calculates the 'simple payback period' for an efficiency upgrade. Which formula is correct?
- Annual Energy Savings ÷ Project Cost
- Project Cost ÷ Annual Energy Cost Savings (Correct answer)
- Annual Energy Cost Savings × Project Life
- Project Cost × Discount Rate
Correct answer: Project Cost ÷ Annual Energy Cost Savings
Simple payback period equals the initial investment divided by the annual cost savings, expressed in years.
Question 6: A facility switches from T12 fluorescent lamps to T8 LED tubes. Besides energy savings, what operational benefit is gained?
- Increased mercury content for recycling value
- Longer lamp life reducing maintenance and replacement costs (Correct answer)
- Higher heat output improving winter comfort
- Broader color spectrum requiring fewer fixtures
Correct answer: Longer lamp life reducing maintenance and replacement costs
LED lamps typically last 50,000+ hours compared to 20,000 hours for T8 fluorescents, significantly reducing maintenance labor and lamp costs.
Question 7: What does 'retro-commissioning' (RCx) mean in the context of building energy efficiency?
- Demolishing and rebuilding a facility using modern materials
- Systematically investigating and optimizing existing building systems to restore or improve performance (Correct answer)
- Installing new HVAC equipment to replace old systems
- Conducting a one-time energy audit with no follow-up
Correct answer: Systematically investigating and optimizing existing building systems to restore or improve performance
Retro-commissioning optimizes existing building systems that were never commissioned or have drifted from optimal performance over time.
EMP Energy Efficiency & Conservation Techniques 3
Which building envelope measure provides the greatest energy benefit in a climate with both hot summers and cold winters?