Know the Lingo: What Every Homebuyer Should Know
An educational series from the RGV New Homes Guide designed to help homebuyers understand the terms, documents, and tests that affect the comfort, indoor air quality, and performance of their new home.
Buying a home is one of the biggest investments you’ll ever make. Yet many buyers hear technical terms without knowing what they really mean. Understanding a few key terms can help you compare homes more confidently—and ask for proof, not just promises.
Climate Zone 1A (Very Hot-Humid)
Prepared/Performed by: International Code Council (ICC) through the 2021 International Energy Conservation Code (IECC)
WHY IT MATTERS:
The Rio Grande Valley is classified as Climate Zone 1A (Very Hot-Humid) under the 2021 IECC. Previously, under the 2015 IECC, the region was classified as Climate Zone 2.
Because South Texas experiences long periods of intense heat and high humidity, homes should be designed with proper insulation, air sealing, humidity control, and correctly sized air-conditioning systems. These features work together to improve comfort, create healthier indoor air, offer durability, and ascertain energy efficiency.
ASK:
- How was this home designed for Climate Zone 1A (Very Hot-Humid)?
- What features help control heat and humidity?
- Was the home designed to exceed the minimum energy-code requirements?
HERS® Score/Energy Rating Index (ERI)
Prepared/Performed by: Licensed third-party Home Energy Rater
WHY IT MATTERS:
A HERS® (Home Energy Rating System) Score is RESNET’s nationally recognized measurement of a home’s expected energy performance. The lower the score, the more energy efficient the home is expected to be, making it an easy way to compare one home with another.
An Energy Rating Index (ERI) is a nationally recognized energy-performance metric used by energy codes and home certification programs to evaluate a home’s expected energy performance. While a HERS Score and an ERI are determined differently and are not interchangeable, both provide an independent way to measure how efficiently a home is expected to perform.
A licensed third-party Home Energy Rater determines a home’s HERS Score or ERI after inspecting the home’s construction features and performing diagnostic testing.
ASK:
- What is the home’s HERS Score or ERI?
- May I see the HERS or ERI Certificate?
Choose a BUILT TO SAVE® certified Builder
For a list of certified BUILT TO SAVE® builders, you can visit www.BuiltToSave.org
Independent Third-Party Certification
Prepared/Performed by: Licensed third-party Home Energy Rater or other qualified program verifier
WHY IT MATTERS:
Some builders voluntarily exceed minimum code requirements by having their homes independently inspected and tested through certification programs such as BUILT TO SAVE®.
Independent inspections verify that important construction details hidden behind the walls were installed correctly, providing confidence that the home’s comfort, indoor air, and energy performance are based on measured results—not marketing claims.
ASK:
- Has this home been independently certified?
- Which certification program was used?
- May I see the certification documents?
Manual J
Prepared/Performed by: HVAC contractor or HVAC designer • Independently verified by: Licensed third-party Home Energy Rater
WHY IT MATTERS:
A Manual J is an engineering calculation used to determine the correct size of a home’s heating and air-conditioning system. It considers the home’s size, insulation, windows, air leakage, orientation to the sun, local climate, amount of lighting and appliances, and expected occupants.
An oversized A/C system may cool the home quickly but won’t run long enough to remove enough humidity. An undersized system may struggle during South Texas summers. Proper sizing improves comfort, humidity control, indoor air, and energy efficiency.
ASK:
- Who prepared the Manual J?
- Was it independently verified?
- May I see the documentation?
Blower Door Test
Prepared/Performed by: Licensed third-party Home Energy Rater
WHY IT MATTERS:
A blower door test measures how much air leaks into and out of a home, producing an Air Changes per Hour (ACH) result.
A tighter home generally provides better comfort, improved humidity control, healthier indoor air, fewer drafts, less dust infiltration, and lower energy bills. Proper air sealing also helps your HVAC system operate more efficiently.
Required by the Texas Energy Code for new homes.
ASK:
- What was the home’s ACH result?
- May I see the blower door test report?
Duct Leakage Test
Prepared/Performed by: Licensed third-party Home Energy Rater
WHY IT MATTERS:
This test measures how much conditioned air escapes through leaks in the home’s duct system.
Properly sealed ducts help deliver conditioned air where it’s needed, improving comfort, healthier indoor air, and energy efficiency while reducing unnecessary strain on the HVAC system.
Required by the Texas Energy Code for most new homes.
ASK:
- What were the duct leakage test results?
- May I see the duct leakage test report?
The Bottom Line
Understanding these terms will help you compare builders more confidently and make a better-informed buying decision.
Don’t hesitate to ask for documentation. Builders who invest in proper design, independent testing, and third-party verification should be proud to show you the results.
Remember: The more you know before you buy, the better home you’ll own. Ask smarter questions. Buy a better home.
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