BPI Building Envelope 4

Question 1

What does a window's U-factor measure?

Accepted Answer

The rate of non-solar heat transfer through the window assembly

Answer

U-factor measures the rate of heat transfer (conduction, convection, and radiation) through a window assembly; lower values indicate better insulating performance.

Question 2

In BPI's building-as-a-system approach, which interaction is most likely to cause CO spillage from a water heater?

Accepted Answer

Air sealing the house without addressing combustion air supply for natural-draft appliances

Answer

Tightening the envelope without ensuring adequate combustion air can depressurize the space, causing natural-draft appliances to spill CO into the living area.

Question 3

Which insulation material has the highest R-value per inch among common residential insulation options?

Accepted Answer

Closed-cell spray foam (R-6.5/inch)

Answer

Closed-cell spray polyurethane foam provides approximately R-6 to R-7 per inch, the highest of common residential insulation products.

Question 4

What is 'effective R-value' as opposed to 'nominal R-value' of a wall assembly?

Accepted Answer

The actual whole-assembly thermal resistance accounting for framing members and thermal bridges

Answer

Effective R-value accounts for heat flow through studs and other thermal bridges in the real assembly, which is typically lower than the insulation's nominal R-value alone.

Question 5

When performing a blower door test, at what pressure differential is the standard CFM measurement taken?

Accepted Answer

50 Pascals

Answer

BPI and ASHRAE standard blower door measurements are taken at 50 Pascals (CFM50), providing a reproducible baseline for airtightness comparisons.

(BPI) Building Performance Institute Certified Practice Test

(BPI) Building Performance Institute Certified Practice Test

BPI Building Envelope 4