CCP Building Envelope & Energy Audit 3 — Questions and Answers
Question 1: During an energy audit, a commissioning professional evaluates a building's Energy Use Intensity (EUI). For a typical US office building, which EUI range (kBtu/ft²/year) is generally considered good performance?
- 150–200
- 100–150
- 50–75 (Correct answer)
- 200–250
Correct answer: 50–75
A good-performing US office building typically achieves an EUI of 50–75 kBtu/ft²/year, significantly below the national median of approximately 90 kBtu/ft²/year.
Question 2: What is the key distinction between a vapor retarder and an air barrier in building envelope design?
- Air barriers resist bulk airflow while vapor retarders resist water vapor diffusion by concentration gradient (Correct answer)
- Vapor retarders are always installed on the warm side while air barriers are on the cold side
- Air barriers apply only to roofs while vapor retarders apply to walls
- They are interchangeable terms for the same building component
Correct answer: Air barriers resist bulk airflow while vapor retarders resist water vapor diffusion by concentration gradient
Air barriers resist bulk airflow driven by pressure differences, while vapor retarders resist moisture diffusion driven by vapor pressure concentration gradients — they address different moisture transport mechanisms.
Question 3: A commissioning professional performing a pre-functional checklist for a curtain wall system should verify which critical installation detail to prevent condensation on interior surfaces?
- Sealant color matches architectural drawings
- Thermal breaks are properly installed at all metal framing members (Correct answer)
- Glass thickness matches specification
- Anchor bolt torque values meet structural engineer's requirements
Correct answer: Thermal breaks are properly installed at all metal framing members
Thermal breaks in curtain wall framing prevent cold metal from conducting to the interior surface, where condensation would form when interior dew point exceeds the surface temperature.
Question 4: An ASHRAE Level II energy audit of a grocery store reveals that refrigerated display cases account for 45% of total electricity use. What energy conservation measure (ECM) would most effectively reduce this consumption?
- Installing LED lighting in the parking lot
- Adding night curtains/covers to open refrigerated display cases (Correct answer)
- Upgrading roof insulation from R-20 to R-30
- Replacing single-pane windows at the storefront
Correct answer: Adding night curtains/covers to open refrigerated display cases
Night curtains on open refrigerated display cases can reduce case energy consumption by 25–40%, representing substantial savings given that cases are typically the dominant energy load in grocery stores.
Question 5: In the context of building envelope commissioning, what does 'hygrothermal analysis' evaluate?
- The structural load capacity of wall assemblies under thermal expansion
- The combined heat and moisture transfer through building assemblies to predict condensation risk (Correct answer)
- HVAC system response to outdoor temperature and humidity changes
- Thermal mass effects on indoor air temperature stability
Correct answer: The combined heat and moisture transfer through building assemblies to predict condensation risk
Hygrothermal analysis (using tools like WUFI) models both heat and moisture transport through building assemblies to predict where and when condensation might occur, guiding insulation placement and vapor control strategies.
Question 6: A commissioning professional finds significant air leakage at the top-plate intersection where interior walls meet the ceiling in an existing building. Which retrofitting approach addresses this air leakage pathway most effectively?
- Adding caulk to all window frames
- Spray foam or sealant application at top plates before insulating the attic (Correct answer)
- Increasing attic insulation depth from R-30 to R-49
- Installing an ERV to compensate for excess infiltration
Correct answer: Spray foam or sealant application at top plates before insulating the attic
Air sealing at the top plate/ceiling intersection before adding insulation directly blocks the primary stack-effect driven leakage pathway that allows conditioned air to bypass into the attic.
Question 7: Which ASHRAE standard provides the primary reference for energy auditing procedures and defines Level I, II, and III audit classifications?
- ASHRAE 90.1
- ASHRAE 211 (Correct answer)
- ASHRAE 62.1
- ASHRAE 55
Correct answer: ASHRAE 211
ASHRAE Standard 211 (Standard for Commercial Building Energy Audits) defines the scope, procedures, and deliverables for Level 1, 2, and 3 commercial energy audits.
CCP Building Envelope & Energy Audit 3
During an energy audit, a commissioning professional evaluates a building's Energy Use Intensity (EUI).
For a typical US office building, which EUI range (kBtu/ft²/year) is generally considered good performance?