During the summer of 2020 a study was conducted to observe the performance differences between homes with a robust building envelope using spray foam insulating air barrier materials, to those with the builder’s standard construction package and compare the utility (electric) usage of each, to determine any energy cost savings.
In early 2020, this local builder had a hybrid BASF HP+™ Wall system installed into the walls of four model homes in a west-side community of Phoenix. To complete the high-performance building envelope, ENERTITE® open-cell spray foam was installed to the underside of the roof deck (with no radiant barrier sheathing). The unvented attic design allows for the mechanical systems to operate more efficiently in this semi-conditioned space, where they are not subjected to extreme Arizona conditions. In fact, in August 2020, when outdoor temperatures exceeded 115°F, data-loggers in the unvented space never exceeded 83°F.
At a different community in the east valley, the builder insulated four model homes of the same floor plans with their standard construction package that included 2x4 exteriors walls with cellulose wall spray, stucco and white EPS continuous insulation. The vented attic was insulated with blown cellulose and radiant barrier sheathing was used.
From May – August 2020, energy usage for the four different floor plans were compared between the two communities. It’s important to note that this was done during the height of the COVID-19 pandemic and the model homes involved in the study were visited on an appointment-only basis by prospective buyers, which resulted in minimal human impact during the study.
