Originally published on Building Enclosure online
Making Sense of Rigid Foams for Continuous Insulation
For high-performance building envelopes, it is important to include a layer of insulation under the floor slab.
At one time, the idea of a zero net energy building seemed like science fiction, similar to flying cars and jetpacks. Yet, as of 2016, there were 332 zero net energy verified buildings in North America, according to the New Buildings Institute. As building owners demand more energy-efficient buildings, and codes become more rigorous, this number will grow, as will the requirements for building insulation.
An examination of building code trends indicates steady movement toward an eventual future of all zero net energy commercial buildings. U.S. Dept. of Energy (DOE) data show that the energy use intensity (EUI) of commercial buildings is nearly 50 percent less under ASHRAE 90.1-2013 than it was under ASHRAE 90A-1980. That trend has accelerated over time, with EUI dropping especially sharply with the adoption of the 2001 and 2007 versions of ASHRAE 90.1.
Of particular note to building envelope professionals, since 2007, ASHRAE 90.1 has required continuous insulation (CI) in most U.S. climate zones. Sixteen states have mandatory statewide commercial energy codes that meet or exceed that standard. California has gone even farther with its Title 24 Energy Efficiency Standards, which call for all new commercial buildings in the state to be zero net energy by 2030.
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