Mixed Deck — All HERS Topics Flashcards

In hot-humid climates, which vapor control strategy is generally recommended for wall assemblies?

Answer: Use vapor-open assemblies on both sides that allow drying to the interior and exterior

In hot-humid climates, walls should be able to dry to either the interior or exterior; trapping moisture with vapor retarders on either side causes problems.

Which water heater type typically has the highest UEF rating?

Answer: Heat pump water heater (HPWH)

Heat pump water heaters achieve UEF ratings of 3.0 or higher because they move heat from surrounding air rather than generating it directly, making them 2-3 times more efficient than electric resistance units.

A rater discovers that the installed attic insulation is R-30 instead of the specified R-49. How does this affect the HERS score?

Answer: The HERS score will be higher (worse) because heat loss through the attic increases

Less insulation than specified increases heat transfer through the attic, raising heating and cooling energy loads and resulting in a higher (worse) HERS Index score.

Which software setting must be configured correctly to distinguish between a conditioned basement and an unconditioned crawl space?

Answer: Foundation type and conditioning status

Foundation type and its conditioning status determine how the software calculates heat loss/gain through below-grade assemblies.

What is a 'guarded blower door test' (also called a two-fan test) used to measure?

Answer: Air leakage between two adjacent dwelling units in a multifamily building

A guarded (two-fan) blower door test uses one fan in each of two adjacent units to equalize pressure between them, allowing measurement of only the leakage to the outside from each unit in multifamily buildings.

What HERS Index score must a home achieve to qualify for the ENERGY STAR Certified Homes Version 3.2 program (new construction)?

Answer: HERS 57 or below depending on climate zone

ENERGY STAR Certified Homes Version 3.2 requires a HERS Index of 57 or below, with the exact threshold varying by climate zone.

Which standard of practice is MOST important for ensuring quality in Energy Modeling Software?

Answer: Following evidence-based protocols while adapting to specific circumstances

Evidence-based protocols provide a foundation of proven practices, but effective Home Energy Rater professionals must also adapt their approach based on specific circumstances and individual case needs within Energy Modeling Software.

Which RESNET standard governs the accreditation of HERS rating software tools?

Answer: RESNET/ICC Standard 301

RESNET/ICC Standard 301 defines the procedures and calculation methods that accredited HERS rating software tools must follow.

Under ANSI/RESNET/ICC 301, what is the reference home used for calculating the HERS Index based on?

Answer: A new home built exactly like the rated home but with standard code features

The HERS reference home mirrors the geometry and features of the rated home but applies standard efficiency values per ANSI/RESNET/ICC 301.

Which factor most significantly reduces the efficiency of a heat pump water heater installed in a small, enclosed mechanical closet?

Answer: Insufficient air volume causing the space to cool excessively and starve the heat pump

HPWHs require adequate air volume (typically 700-1,000 cubic feet minimum) because they extract heat from surrounding air; an enclosed closet quickly cools to the point where efficiency drops dramatically.

Why is mastic sealant generally preferred over standard duct tape for sealing duct leaks?

Answer: Mastic remains flexible and durable, while duct tape adhesive degrades over time

Mastic sealant maintains a durable, flexible seal over years of thermal cycling, whereas standard duct tape adhesive dries out and fails, allowing leaks to reopen.

Which federal law requires raters working in homes built before 1978 to follow lead-safe work practices?

Answer: EPA RRP Rule

The EPA's Renovation, Repair, and Painting (RRP) Rule mandates lead-safe practices in pre-1978 homes to protect occupants and workers.

When converting CFM50 to Equivalent Leakage Area (ELA), which pressure reference is typically used in the US?

Answer: 25 Pascals

In the US, ELA is referenced at 4 Pa for Canadian standards, but the most common US reference for Effective Leakage Area is 4 Pa while ELA at 10 Pa is used in some protocols; however, RESNET typically uses 4 Pa — but the standard US ELA reference in blower door analysis is 4 Pa.

What does the term 'total duct leakage' (Qtotal) represent in duct blaster testing?

Answer: All air leaking from the duct system into both conditioned and unconditioned spaces

Qtotal measures all air escaping the duct system regardless of destination — into conditioned space, unconditioned space, or outside.

A rater finds that a spray-foam insulated cathedral ceiling has no ventilation channel between the foam and the roof deck. How should this be handled in the HERS rating?

Answer: Verify the foam type and thickness; unvented assemblies are acceptable if designed per code with adequate R-value

Unvented cathedral ceiling assemblies are code-compliant when properly designed with sufficient closed-cell or open-cell foam meeting IRC Section R806.5 requirements; the rater verifies the design, not the ventilation gap.

What happens to a home's HERS score if window area is significantly increased without changing window U-factor or SHGC?

Answer: Score typically worsens due to increased conductive losses and solar gains

Increasing window area with the same U-factor and SHGC increases both conductive heat loss and unwanted solar gain, generally raising the HERS score.

According to building science principles, where should the air barrier be located relative to the insulation layer?

Answer: At or near the insulation layer but its exact position depends on climate

The optimal air barrier location depends on climate — it should be positioned to prevent moisture-laden air from reaching surfaces where condensation could occur.

Which IECC section requires builders to provide a list of energy features (certificate) to the building owner at the time of occupancy?

Answer: R401.3

IECC Section R401.3 requires a certificate listing the home's energy features — including insulation levels, window U-factors, and equipment efficiencies — to be posted or provided at occupancy.

When using a duct blaster to measure duct leakage to outside (Qout), the technician must cancel out house leakage. Which technique accomplishes this?

Answer: Simultaneously operating the blower door to maintain house pressure equal to duct pressure

The simultaneous blower door and duct blaster technique pressurizes the house to equal the duct test pressure, canceling house leakage so only duct-to-outside leakage is measured.

What is the minimum SEER2 rating required for a central air conditioner to qualify as efficient under current federal standards (effective 2023)?

Answer: 14 SEER2 in northern states, 15 SEER2 in southern states

As of January 1, 2023, the federal minimum efficiency is 14 SEER2 for the North region and 15 SEER2 for the South and Southwest regions.