CEC Promotes “Skinny” Triple Glazed Windows as Solution to Title 24’s Challenge

During the AAMA Western Region Summit, Payam Bozorchami with the CEC discussed an important element of the 2019 California Energy Standard - the energy design rating (EDR) metric.

EDR, the ratio of Time Dependent Valuation (TDV) energy used by a proposed home to the TDV of a 2006 IECC-compliant home, can be used to determine compliance with the California Energy Standard (Title 24). The resulting EDR score ranges from 0 to 100, with zero being a full Zero Net Energy (ZNE) building, while 100 is an IECC-compliant building. It provides builders with flexibility to meet performance targets. Buildings compliant with the 2019 California Energy Standards will typically have EDR scores in the 15 to 27 range.

Increased window efficiency is a major element to improve the EDR score of the residential building envelope. Along these lines, Bozorchami described the advanced thin center glass triple pane window – a recent product development that achieves triple pane ratings within the typical thickness of a double pane window (~18 mm) by placing a thin (0.7 mm) glass layer between the standard outer layers (3 mm). Low-E coatings on surfaces 2 and 5, krypton gas fill and the use of a foam spacer rounds out the configuration. The U-factor is reduced from typically 0.33 to 0.25 or as low as 0.14 (R-7).

Because the design has the same dimensions and about the same weight as a double-pane window, it is an attractive solution that can be used in new products and to retrofit existing frames. Plus, the design can be produced at reasonable cost.

“The two manufacturers who are already making thin triple pane windows have reported no issues with testing, including structural, or shipments of these products,” said Bozorchami.

Formed in mid-2018, the California Partnership for Advanced Windows (C-PAW) facilitates market adoption of the Thin Triple solution. Additionally supported by Lawrence Berkeley National Labs and several state utilities, as well as cooperating window manufacturers, the organization offers an Online Resource Center (ORC) at energy.ca.gov/title24/orc.

In addition, the quarterly email Blueprint Newsletter offers clarifications on frequently asked questions; users may subscribe via energy.ca.gov/efficiency/blueprint. Also, to receive email updates on the California Energy Standards, sign up at energy.ca.gov/listservers.