HERS HERS Thermal Envelope Insulation and Air Sealing

Question 1

In HERS energy modeling, what is the thermal performance metric used to describe the insulating value of a wall assembly including all components?

Accepted Answer

Assembly R-value (whole-wall R-value)

Answer

Whole-wall or assembly R-value accounts for all components including framing, insulation, sheathing, and cladding for an accurate thermal performance measure.

Question 2

A HERS rater is inspecting a home with spray polyurethane foam (SPF) insulation in the roof deck. What ventilation configuration applies to this assembly?

Accepted Answer

Unvented conditioned attic — the HVAC system must be inside the thermal envelope

Answer

Spray foam applied to the roof deck creates an unvented conditioned attic, requiring that HVAC equipment and ducts be inside the thermal envelope.

Question 3

What is the RESNET-recognized default infiltration rate used for the Reference Home in HERS Index calculations?

Accepted Answer

7 ACH50

Answer

RESNET uses 7 ACH50 as the default infiltration rate for the Reference Home when no blower door test is performed.

Question 4

Which area of a home typically accounts for the greatest air leakage in standard U.S. construction according to blower door diagnostic studies?

Accepted Answer

Top plates and ceiling penetrations

Answer

Top plates and ceiling penetrations (can lights, plumbing, wiring) are the largest source of air leakage in most U.S. homes.

Question 5

A HERS rater verifies continuous rigid foam insulation on the exterior of a wall assembly. What thermal performance benefit does this provide beyond cavity insulation alone?

Accepted Answer

Elimination of thermal bridging through framing members

Answer

Continuous exterior insulation eliminates thermal bridging through studs, dramatically improving whole-wall R-value.

(HERS) Certified Home Energy Rating System Rater Practice Test

(HERS) Certified Home Energy Rating System Rater Practice Test

HERS HERS Thermal Envelope Insulation and Air Sealing