Dear ENERGY STAR Residential New Construction Stakeholder, The ENERGY STAR Single-Family New Homes program has finalized a new time-limited allowance related to Concrete Masonry Unit (CMU) block walls. CMU blocks are commonly used to construct residential exterior walls in some parts of the country, such as Florida and southern Texas. One practice for insulating such walls is to fill the hollow cores by injecting spray foam through holes drilled into the side of the wall. In July, RESNET affirmed (via an interpretation request) that CMU block wall assemblies are currently unable to achieve Grade I, which is a mandatory requirement for the ENERGY STAR Single-Family New Homes program. Since then, efforts have been underway within RESNET to develop new protocols that would allow insulation installed in the core of CMU block walls to be assigned a grade other than III. To allow this process to continue without requiring partners pursuing certification to immediately change insulation strategies, CMU block wall assemblies with Grade III insulation filling the cores are allowed to be used in ENERGY STAR certified homes permitted prior to 1/1/26. This new allowance has been added to the ENERGY STAR Policy Record and will appear in Footnote 4 of the National Rater Field Checklist with the upcoming release of Revision 14, as follows: “…CMU block wall assemblies with Grade III insulation filling the cores are permitted to be used in homes permitted prior to 1/1/26, to provide an opportunity for standards bodies to consider a protocol that may allow such assemblies to achieve Grade I.” This new allowance has been added to the ENERGY STAR Policy Record and will appear in Footnote 4 of the National Rater Field Checklist with the upcoming release of Revision 14, as follows: “…CMU block wall assemblies with Grade III insulation filling the cores are permitted to be used in homes permitted prior to 1/1/26, to provide an opportunity for standards bodies to consider a protocol that may allow such assemblies to achieve Grade I.” Please feel free to forward this information to other interested stakeholders working in the residential new construction market. Best Regards, ENERGY STAR Residential New Construction Team
