Building “green” means lots of different things for homeowners as well as homebuilders. This isn’t surprising considering the array of green building certification programs in the United States today, such as Energy Star, LEED, ICC-700 National Green Building Standard, Earth Advantage, and Passive House (see “Green Home Certifications” sidebar).
Despite the differences, the most important element of any green building strategy is maximizing energy efficiency. And the biggest impact you can have on energy use is by building smaller. According to the Oregon Department of Environmental Quality, in the 70-year life of a U.S. home, the largest use of energy is in occupancy use—not the embodied energy or end-of-life deconstruction costs. And smaller homes typically require less energy for their operation. Of course, water conservation, maintaining good indoor air quality, using resources efficiently, embodied energy, and site impact also come into play.
As a green designer eager to start a new project, I was happy to hear from builder Gary Dorris when he called me in June 2012 to talk about an interesting one. We had worked together on an Earth Advantage Platinum-certified home a couple of years ago—the beginning of a great working relationship.
Gary wanted me to meet Brad Hagen and Linda Niehaus, who were moving to southern Oregon from central Washington. Gary told me they wanted to build an energy-efficient home, but needed help with the design. From the beginning, Brad and Linda knew they wanted their new home to be energy-efficient and oriented for passive solar gain as well as for active solar systems.
Beyond the thermal performance of their home, Brad and Linda had simple design requirements: a single-story, two-bedroom modern home. They also wanted to keep it around 1,000 square feet, which I’m delighted to say is being requested more often these days—the philosophy of living simply is resonating with a broader segment of the population. Much of what I know about smaller living spaces I have learned from architect and author of the “Not-So-Big” books, Sarah Susanka: Quality is better than quantity, define spaces without walls, light is good, and details in the finish can make your home unique and personal.
The first lot Brad and Linda looked at failed to work because of the neighborhood covenants, conditions, and restrictions, which did not allow a modern design. But Linda knew what she was looking for and it did not take too long to find an alternate site: a narrow lot, 45 feet wide by 120 feet long, with a good solar window. Only 10 blocks from the center of town, it was good location for easy access to services.
I attempted to simplify the decision-making process by offering three different design levels for the building envelope. Gary had worked with several homes constructed with structural insulated panels (SIPs), and appreciated the ease and speed with which the envelope could be assembled, so I specified SIPs for the entire envelope.
Level one was the “green” package, which exceeds the existing Oregon building energy codes for R-values. This design includes R-24 SIP walls, an R-40 SIP roof, and 2 ACH50 (air changes per hour at a pressure of 50 pascals—see “Build It Tight, Ventilate It Right” sidebar). “Greener” is a good step up, with R-32 SIP walls, an R-48 SIP roof, and 1 to 2 ACH50. Both levels one and two were estimated to cut thermal bridging by about 40% compared to standard stud construction. This improvement can result in heating and cooling energy savings of 15% to 20%.