Streamlined Calculation with UA for New ENERGY STAR Requirements

Streamlined Calculation with UA for New ENERGY STAR Requirements
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Requirements for the new v3.2 ENERGY STAR certification, in place as of January 2025, mean builders need to meet or exceed higher standards for wall insulation. DuPont’s calculator can help.

As builders make the transition to ENERGY STAR Single-Family New Homes Version 3.2, which aligns with the standards set by 2021 IECC for insulation, they’ll need to make a notable jump compared to the 2012 IECC that was referenced in previous versions of the ENERGY STAR program.

Homes certified under the latest version are expected to achieve at least 10% savings over the 2012 IECC requirements, with higher gains in states that have yet to adopt the 2021 IECC.

There are a variety of methods builders can use to reach those next levels of new insulation and air-sealing standards.

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Code Compliance Paths: Prescriptive vs UA

Builders and architects can rely on a prescriptive method with a table that specifies the steps needed to achieve or exceed the new requirements, but that method can be restrictive.

Simulated performance methods and Energy Ratings Indexes are options that provide more flexibility, but they are whole home energy analysis systems that may be more complex and often require a third party to perform. The simulated performance method compares the modeled energy cost of a designed home with a reference home. The Energy Ratings Index method requires bringing in a professional rater, such as for a HERS (Home Energy Rating System) score.

The UA alternative method focuses only on envelope thermal efficiencies without needing to model the energy use of the entire home. A “U value” is the unit heat flow per area - a way to measure systems that contribute to energy efficiency, compared to an “R value” that measures materials. A U value demonstrates how much heat can flow through an area, while an R value shows how much resistance there is to the heat. A UA calculator measures U value times area.

“A UA calculator allows you to trade off where you install insulation,” says William Ranson, Building Knowledge Center Leader for DuPont. “If you’re using a prescriptive method to determine your insulation needs, you don’t have that flexibility to choose the products and installation methods that work for your individual project. For example, continuous insulation (CI) works well if you have a lot of surface area, and you may not need to upgrade to more expensive thermal windows or add thicker roof insulation to meet the requirements.”

DuPont’s UA calculator can simplify the calculation process to help builders easily meet the new rules without sacrificing home performance and without significantly raising overall wall assembly costs.

“Most builders don’t have a calculator like our proprietary UA calculator, which we can use to run through a variety of options and tradeoffs to find the most effective, simple and cost-efficient way to design and install wall assemblies,” Ranson says.

Consultative Approach with UA Calculator

When builders and architects work with DuPont on their insulation plans, they get more than access to the UA calculator.

“While we think our calculator is an efficient way to work through decisions, the true value isn’t just to run the calculator and come up with one great option,” says Aaron Grin, Residential Applications Technology Leader at DuPont. “The value is in the discussion with an expert and the opportunity to discover new products and to realize what’s possible.”

Most builders use the prescriptive method but there’s no easy lever that they can use to swap out options to evaluate their impact, Grin says. The UA calculator includes comparison options based on specific climate zones.

“For example, if you have an R-49 roof with R-20 cavity insulation, you can achieve the same level of energy efficiency with an R-28 roof, one inch of CI and R-20 in the cavity for a much better value package,” says Grin.

To learn more about DuPont Styrofoam and to schedule a consultation, visit www.dupont.com/building/styrofoam-continuous-insulation.html