Energy Modeling and Analysis Flashcards
7 cards from real HERS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Energy Modeling and Analysis flashcards as text
What is the primary purpose of TMY (Typical Meteorological Year) weather data files in HERS energy modeling?
Answer: To represent a statistically typical year of hourly weather data used to simulate annual energy consumption
TMY files contain representative hourly data assembled from multiple years to reflect typical (not extreme) conditions, enabling accurate annual energy simulation.
A HERS rater is modeling a home with an ERV (Energy Recovery Ventilator). Which additional performance value beyond airflow rate must be entered to accurately model energy recovery?
Answer: The sensible recovery efficiency (SRE) and total recovery efficiency (TRE) or sensible and latent effectiveness values
Accurate ERV modeling requires sensible and total (or latent) recovery efficiencies to quantify how much heating and cooling energy is recaptured from exhaust air.
In the context of HERS ratings, what is 'source energy' and how does it differ from 'site energy'?
Answer: Site energy is measured at the home; source energy accounts for generation and transmission losses back at the power plant
Site energy is measured at the meter, while source energy traces consumption back through generation and transmission, using fuel-specific site-to-source multipliers.
How does HERS modeling handle the energy contribution of a photovoltaic (PV) system when calculating the HERS Index?
Answer: PV generation offsets the home's rated energy use, potentially resulting in a HERS Index below zero for net-zero or net-positive homes
Per ANSI/RESNET/ICC 301, PV generation is credited against the Rated Home's energy use and can produce a HERS Index of zero or below for homes that generate as much or more than they consume.
What modeling approach is used for mass walls (e.g., concrete masonry) that is different from light-frame wood walls?
Answer: Mass walls require dynamic thermal mass properties (heat capacity) in addition to R-value to accurately model time-delayed heat transfer
Thermal mass stores and releases heat with a time delay, so accurate modeling requires both R-value and heat capacity inputs to capture the mass wall's dynamic buffering effect.
A rater models two identical homes except one has east/west-facing glazing and the other has south/north-facing glazing. In a heating-dominated climate, which will likely have a lower HERS Index?
Answer: The south/north-facing home because south windows maximize passive solar gains in winter
South-facing windows capture winter solar gains more effectively than east/west windows, reducing heating energy and lowering the HERS Index in heating-dominated climates.
Which RESNET standard governs the technical requirements for HERS energy modeling software to be approved for use in ratings?
Answer: RESNET Publication 002
RESNET Publication 002 (Mortgage Industry National Home Energy Rating Standards) establishes software approval criteria and testing protocols for HERS rating tools.