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.