CEA Energy Auditing & Assessment Techniques 5 — Questions and Answers
Question 1: In an energy audit context, 'phantom loads' (also called standby or vampire loads) refer to:
- Energy consumed by plug-in devices while switched off or in standby mode (Correct answer)
- Unaccounted energy losses in the electrical distribution system
- Peak demand spikes caused by motor starting currents
- Heat gains from occupants and equipment counted in cooling load calculations
Correct answer: Energy consumed by plug-in devices while switched off or in standby mode
Phantom loads can account for 5–10% of residential and small commercial electricity use; smart power strips and occupancy-based controls reduce them.
Question 2: An energy auditor recommends a variable frequency drive (VFD) on a constant-volume pump. The energy savings potential follows the affinity laws, meaning a 20% speed reduction yields approximately:
- 49% reduction in power consumption (cube law relationship) (Correct answer)
- 20% reduction in power consumption (linear relationship)
- 40% reduction in power consumption (square law relationship)
- 60% reduction in power consumption (fourth-power relationship)
Correct answer: 49% reduction in power consumption (cube law relationship)
Per the affinity laws, pump power varies with the cube of speed: (0.80)³ = 0.512, meaning a 20% speed reduction reduces power by approximately 49%.
Question 3: When reviewing a building's energy model during an audit, the auditor finds that the simulated EUI closely matches the actual utility EUI. This means the model is:
- Calibrated and can be used to reliably predict savings from proposed energy conservation measures (Correct answer)
- Incorrectly set up because actual and modeled values should never match
- Ready for submission as a Level I audit deliverable without further analysis
- Proof that no energy conservation opportunities exist in the building
Correct answer: Calibrated and can be used to reliably predict savings from proposed energy conservation measures
A calibrated energy model that matches actual utility data is a reliable tool for predicting ECM savings and is the foundation of investment-grade (Level III) audits.
Question 4: A 'short-circuit factor' in duct leakage testing refers to:
- Supply air leaking directly into return air pathways before conditioning occupied spaces (Correct answer)
- Electrical short circuits discovered in HVAC control panels during audits
- The ratio of outdoor air to return air in a mixed-air HVAC system
- Condensate drain bypass around the cooling coil during high humidity periods
Correct answer: Supply air leaking directly into return air pathways before conditioning occupied spaces
Supply-to-return duct leakage short-circuits conditioned air, reducing HVAC effectiveness and forcing the system to work harder to maintain setpoints.
Question 5: During a renewable energy feasibility assessment as part of an energy audit, which factor is MOST critical in evaluating a rooftop solar PV installation?
- Roof orientation, tilt angle, and shading analysis to determine annual solar irradiance (Correct answer)
- The building's existing fuel type for space heating
- The number of building occupants and their daily schedules
- Distance from the building to the nearest natural gas distribution main
Correct answer: Roof orientation, tilt angle, and shading analysis to determine annual solar irradiance
Solar resource quality—determined by orientation, tilt, and shading—directly governs PV system output and is the primary technical determinant of project viability.
Question 6: An energy auditor uses a 'load disaggregation' technique. What is the primary goal?
- To break down total building energy use into contributions from individual end uses (HVAC, lighting, plug loads, etc.) (Correct answer)
- To separate on-peak from off-peak electricity consumption for demand response programs
- To calculate the carbon footprint of each energy source consumed on site
- To divide an audit project scope among multiple engineering subcontractors
Correct answer: To break down total building energy use into contributions from individual end uses (HVAC, lighting, plug loads, etc.)
Load disaggregation allocates metered consumption to specific end uses, enabling auditors to prioritize ECMs that target the largest energy consumers.
Question 7: Under the Energy Policy Act (EPAct) and related standards, which type of building is REQUIRED to benchmark energy performance using ENERGY STAR Portfolio Manager?
- Federal buildings over 5,000 square feet must report energy use annually under federal mandates (Correct answer)
- All residential single-family homes built before 1990
- Retail establishments with more than 10 employees in any state
- Industrial facilities using more than 500,000 BTU per hour of process heat
Correct answer: Federal buildings over 5,000 square feet must report energy use annually under federal mandates
Federal agencies are required by law (EPAct 2005, EO 13693) to benchmark all buildings over 5,000 sf in ENERGY STAR Portfolio Manager and report annually.
CEA Energy Auditing & Assessment Techniques 5
In an energy audit context, 'phantom loads' (also called standby or vampire loads) refer to: