HERS Ventilation & Indoor Air Quality 2

Question 1

An HRV (Heat Recovery Ventilator) differs from an ERV (Energy Recovery Ventilator) in that an HRV:

Accepted Answer

Transfers only sensible heat between airstreams without transferring moisture

Answer

Transfers both sensible heat and moisture between incoming and outgoing airstreams

Answer

Only provides conditioned supply air without any heat recovery

Answer

Is specifically designed for hot-humid climate zones

Question 2

In which climate condition is an Energy Recovery Ventilator (ERV) generally preferred over a Heat Recovery Ventilator (HRV)?

Accepted Answer

Hot-humid climates (IECC zones 1-3) where moisture control is critical

Answer

Cold climates (IECC zones 6-8) with very low winter humidity

Answer

High-altitude climates with extremely dry air year-round

Answer

Mixed-dry climates where no humidity management is needed

Question 3

A supply-only ventilation system in a hot-humid climate can create which building science concern?

Accepted Answer

Pressurization that drives warm humid air into wall cavities, risking moisture damage

Answer

Depressurization that draws soil gases into the conditioned space

Answer

Reduced blower door test results below program minimums

Answer

Backflow of combustion gases from sealed-combustion appliances

Question 4

An exhaust-only ventilation system draws outdoor replacement air into the home primarily through:

Accepted Answer

Intentional envelope leakage paths and passive fresh air inlets

Answer

A dedicated supply duct connected to the air handler return

Answer

An HRV or ERV core mounted at the air handler

Answer

The plumbing drain-waste-vent (DWV) stack

Question 5

What is the typical sensible heat recovery efficiency range for a quality residential HRV unit under rated conditions?

Accepted Answer

70–85%

Answer

20–40%

Answer

45–65%

Answer

90–99%

Question 6

A HERS rater measures a home's exhaust-only ventilation fan at 35 CFM, but the ASHRAE 62.2 design requirement is 45 CFM. This system is:

Accepted Answer

Non-compliant, since measured flow is more than 10% below the design rate

Answer

Compliant, since it is within 25% of the design rate

Answer

Compliant, since any rate above 30 CFM satisfies minimum requirements

Answer

Compliant if operable windows are present in all sleeping areas

Question 7

When verifying ventilation compliance during a HERS rating, the rater typically documents ventilation performance by recording:

Accepted Answer

Measured airflow rate in CFM using a flow hood, anemometer, or fan flow meter

Answer

Static pressure at the air handler supply plenum

Answer

Duct leakage to outdoors from the duct pressurization test

Answer

Blower door CFM50 result from the air sealing test