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RESNET / ACCA Standard 310 is HERE!

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Several years ago, Residential Energy Services Network (RESNET) and ACCA began discussions about how the Home Energy Rating System (HERS) Index should reflect the installation of the largest energy-using appliance in homes across America, the HVAC system. Three years ago, RESNET formed a working group to draft the standard, which is now an American National Standard! Download RESNET/ACCA Standard 310-2020 “Standard for Grading the Installation of HVAC Systems” now.

What Is in RESNET / ACCA Standard 310?

The standard outlines five separate tasks that can be performed by the HVAC professional or a HERS Rater. These tasks evaluate and grade aspects of the HVAC system’s installation and performance. These tasks are non-intrusive or have minimal impact (make a hole for a static pressure probe). HVAC professionals would use the Independent Verification Report process outlined in the standard.

What Does Standard 310 Do?

Standard 310 provides the guidance to collect the data that is factored into lowering the HERS or ERI score. The closer your installation comes to compliance with the standard, the better the HERS or ERI score will be.

This standard focuses on forced-air cooling and heat pump heating. Therefore, climates, which are cooling dominant or regions that use heat pumps, will see a better opportunity to improve their HERS Index / ERI scores. Climates with short cooling seasons will see less impact on their score since there is less time spent cooling (or heat pump heating).

What Does Standard 310 Require?

The standard’s five tasks consist of two prerequisite tasks that must be passed before the process can continue, and three functional tests that directly contribute to a better HERS / ERI score.

  1. Prerequisite: HVAC System Design – Ensure the dwelling’s attributes are correctly modeled, and ensure the dwelling was built per the design. This looks at key contributors to the homes heat loss/gain, and confirms those elements are present as specified.
  2. Prerequisite: Total Duct Leakage – confirm that the duct system is tight. Leaky ducts could mask problems that exhibit low static pressure and low fan watt draw. However, the conditioned air could be leaking into unconditioned space where it does not promote comfort.
  3. Task: Airflow – Several different methods can be used to confirm that system airflow is within a tolerance of the design airflow.
  4. Task: Fan Watt / Cfm – This metric is not cited in the ACCA 5 QI Standard at this time; however, this metric reflects the duct system’s efficiency. A fan that uses less energy to move the design airflow is more desirable than a fan that must draw heavily to turn the fan to achieve the same airflow.
  5. Task: Refrigerant Charge – The Rater takes a series of temperature measurements indoors, outdoors, and at the refrigerant lines. Or proof the weigh-in method was used is also accepted.

What’s In It For Me

RESNET has heard from Homebuilders that if they demonstrate compliance with the standard, it will help them meet the qualifications to earn the 45L tax credits. (To learn more about the 45L Tax Credit read this.) This is the first potential financial incentive for home builders to hire HVAC professionals who will deliver quality installations. These incentives can earn the Homebuilder a $2,000 tax credit. This is not a tax deduction that reduces their tax bill slightly, but a tax credit that reduces what they owe (or increases what is owed to them). Builders who earn the credit would have a $2,000 incentive to hire an HVAC professional who delivers a quality installation. That is, an HVAC system that is properly designed, with commissioned equipment and a tight duct system.

Feedback Request

Please respond to this survey and answer five questions about whether ACCA should modify the QI mobile app for use to earn the HERS or ERI points for a home builder. The QI app is currently only applicable to retrofit or replacement systems in existing homes. However, ACCA Quality Assured accredited contractors can download the app and experiment with how to use it.
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