HERS Energy Modeling and Analysis Questions and Answers

Question 1

A HERS Rater completes an energy model for a new home, resulting in a HERS Index of 55 and an estimated annual energy cost of $1,500.
The homeowner, who works from home and keeps the thermostat at 75°F in the summer, receives their first-year utility bills totaling $2,200.
What is the most likely explanation for the discrepancy between the modeled cost and the actual cost?

Accepted Answer

The actual operating conditions and occupant behavior differed from the standardized assumptions used in the model.

Answer

The energy modeling software has a mandatory +/- 50% margin of error.

Answer

The rater must have entered the wrong utility rates into the software.

Answer

The blower door test result was inaccurate, causing the model to be invalid.

Question 2

According to the RESNET/ANSI 301 Standard, which of the following attributes of the HERS Reference Home is set to be identical to the Rated Home to create a basis for comparison?

Accepted Answer

Building geometry, size, and orientation

Answer

Window efficiency (U-factor and SHGC)

Answer

Air leakage rate (ACH50)

Answer

HVAC system efficiency (AFUE/SEER)

Question 3

An energy model for an existing home in a cold climate results in a HERS Index of 120. To determine the most cost-effective upgrade recommendation, what is the best first step for the rater to take using the modeling software?

Accepted Answer

Create separate model files for each potential upgrade to isolate its individual impact on the HERS Index and energy cost.

Answer

Combine all potential upgrades into a single improved model to show the maximum possible savings.

Answer

Use the software's default IECC Code compliance improvement package without modification.

Answer

Adjust the utility rates in the software to see how cost savings change with different energy prices.

Question 4

When creating a 'Confirmed Rating' for a new home, which of the following inputs MUST be determined by on-site performance testing rather than being taken from construction plans or default values?

Accepted Answer

The envelope leakage rate (ACH50).

Answer

The R-value of the wall insulation.

Answer

The Solar Heat Gain Coefficient (SHGC) of the windows.

Answer

The foundation type (slab, crawlspace, or basement).

Question 5

Which of the following best describes the primary purpose of using standardized operating conditions (e.g., thermostat settings, number of occupants, internal gains) in a HERS rating energy model?

Accepted Answer

To provide a consistent, repeatable basis for comparing the energy efficiency of different homes, regardless of occupant behavior.

Answer

To accurately predict the future energy bills for the specific family that will occupy the home.

Answer

To meet the minimum data input requirements for federal tax credit applications.

Answer

To simplify the data entry process and reduce modeling time for the HERS Rater.

Question 6

A HERS Rater is modeling a two-story home with a vented, unconditioned attic. The attic floor is insulated, and the air handler and all ductwork are located in this attic. How must the location of the duct system be specified in the energy modeling software for an accurate rating?

Accepted Answer

Outside conditioned space.

Answer

Inside conditioned space, because it serves the house.

Answer

In a buffer space, such as an unconditioned basement.

Answer

The location does not need to be specified if duct leakage is tested.