Varieties of Prefabricated Envelope Solutions for California Low-rise Buildings

The decarbonization of California’s building sector has fostered the need for global collaboration on emerging technologies. REALIZE California (hereafter referred to as REALIZECA) is an innovative approach to decarbonizing aging multifamily affordable housing statewide. By focusing on the rapid deployment of streamlined retrofit packages tailored to the most common building typologies in the state’s multifamily affordable housing stock, REALIZE-CA provides a roadmap for transforming buildings and communities. 

To scale deployment of zero net carbon retrofits, significant advances in the standardization and delivery of envelope retrofit systems are needed. European retrofit markets have successfully achieved this by creating unitized, prefabricated, airtight, and high R-value panels that are hung from the building exterior and include high performance windows and doors. A complete roof and wall townhouse retrofit can be installed in as little as one day. These types of prefabricated retrofit panels, however, are not available in the United States or designed to serve California’s building stock and climate. 

Through this project, REALIZE-CA demonstrated emerging prefabricated envelope solutions as part of a standardized retrofit package for California’s aging multifamily buildings. Specifically, the research team designed, fabricated, and tested two variations of prefabricated envelope panel prototypes on the most common multifamily building typology in California: low-rise, wood-frame buildings. Project findings demonstrate the following:

• Light-touch envelope solutions are sufficient for package deployment in the California affordable multifamily retrofit market at this time.
• Improving the market’s access to insulated over-cladding strategies will require greater funding coordination and quantification of non-energy benefits.
• Whole-building retrofits can be more cost-effective than traditional, site-built renovation/rehabilitation projects.
• Industrialized panelization is not the key to unlocking this opportunity