A key element of building an energy-efficient home is minimizing airflow and heat transfer. That means paying extra attention to wall assemblies, especially in trouble areas where wall sections face unconditioned spaces like attic knee walls, skylight wells, the space behind gas fireplace inserts and behind showers or tubs on exterior walls. Traditional wall assemblies are four-sided structures, but considerable gains can be made by opting for six-sided assemblies.

Opting for six-sided wall assemblies is a relatively simple enhancement that dramatically increases home efficiency and comfort. And it’s also one of the energy-saving features required to earn an EPS^TM, Energy Trust’s energy performance score for high-efficiency homes.

To stop airflow and reduce heat transfer, walls need interior and exterior rigid or semi-rigid air barriers, often in the form of gypsum board, OSB, plywood, thermoply and rigid insulation. For the wall to be truly efficient, the air barrier and insulation must also be aligned to work in tandem—six-sided wall assemblies make this possible.

With a traditional four-sided assembly, there’s a bottom plate, studs and a top plate. Drywall and sheathing make up the other sides. While insulation will fill the gaps between studs, heat transfer can occur when a side of the assembly is open to air and enables it to move through the insulation. The six-sided assembly solves this issue and simply requires adding a rigid or semi-rigid air barrier on the side of the wall assembly that’s not boxed in.

The combination of six-sided assemblies and properly installed insulation brings many benefits, including lower energy use, less demand on the heating and cooling system, and comfortable temperatures throughout the home.

For builders looking to receive an EPS, six-sided assemblies meet the requirement for fully aligned air barriers with insulation and will also help improve the home’s energy performance score.

Download Energy Trust’s EPS Field Guide and watch training videos for more information and other energy-saving EPS requirements.