BPI Energy Auditing 2 — Questions and Answers
Question 1: What does a blower door test measure in a residential energy audit?
- Air leakage rate of the building envelope (Correct answer)
- Duct system static pressure
- HVAC equipment efficiency
- Window U-factor
Correct answer: Air leakage rate of the building envelope
A blower door test depressurizes the home to measure air infiltration through the building envelope in CFM50 or ACH50.
Question 2: Which BPI standard unit is used to express overall building air leakage from a blower door test?
- CFM25
- CFM50 (Correct answer)
- ACH natural
- Pascal
Correct answer: CFM50
CFM50 (cubic feet per minute at 50 Pascals of depressurization) is the standard BPI unit for reporting whole-building air leakage.
Question 3: During a combustion safety test, what is the maximum acceptable CO level in undiluted flue gases from a natural draft furnace per BPI standards?
- 100 ppm
- 200 ppm
- 400 ppm (Correct answer)
- 800 ppm
Correct answer: 400 ppm
BPI standards require that CO in undiluted flue gases not exceed 400 ppm for natural draft appliances.
Question 4: What is the purpose of a duct blaster test in an energy audit?
- Measure duct insulation R-value
- Determine duct system air leakage to the outside (Correct answer)
- Assess airflow at registers
- Calculate duct static pressure drop
Correct answer: Determine duct system air leakage to the outside
A duct blaster pressurizes the duct system to quantify leakage, particularly leakage to unconditioned spaces.
Question 5: An energy auditor finds a draft hood equipped water heater failing the worst-case CAZ depressurization test. What is the appropriate immediate action?
- Note it in the report and continue the audit
- Red-tag the appliance and notify the homeowner (Correct answer)
- Increase flue pipe diameter
- Replace the thermocouple
Correct answer: Red-tag the appliance and notify the homeowner
A failed worst-case depressurization test indicates a spillage/backdrafting hazard; the auditor must red-tag the appliance and inform the occupant.
Question 6: What does the term 'thermal bypass' refer to in building science?
- Heat loss through windows with low emissivity coatings
- Airflow that carries heat around or through insulation (Correct answer)
- Heat transfer via ground contact
- Radiant heat gain through roofing materials
Correct answer: Airflow that carries heat around or through insulation
A thermal bypass occurs when air movement carries heat around insulation, dramatically reducing its effective R-value.
Question 7: Which of the following best describes the 'stack effect' in a building?
- Pressure-driven air movement caused by temperature difference between inside and outside (Correct answer)
- Heat stratification in a forced-air duct system
- Moisture accumulation in wall cavities during winter
- Radiant heat transfer through high ceilings
Correct answer: Pressure-driven air movement caused by temperature difference between inside and outside
The stack effect is buoyancy-driven air infiltration where warm indoor air rises and escapes at the top, drawing cold outside air in at the bottom.
BPI Energy Auditing 2
What does a blower door test measure in a residential energy audit?