There are many avenues available to assist in determining just how “green” a new home can be, where the emphasis is on energy savings, enhanced comfort, and healthier indoor air quality. In all cases, true certification comes with the services of a disinterested third-party verifier. Most programs are based on the number of points earned in each of several categories, including energy, air quality, materials, environment, and water. Below are the programs readily available in the Pacific Northwest.
The Northwest Energy Star Homes program is a regional initiative of the Environmental Protection Agency (EPA) where the emphasis is on energy efficiency. Homes with the Energy Star label are projected to be at least 15% more efficient than homes built to current state building codes. This is accomplished by limiting the windows-to-floor area to 21%, and requiring high-performance HVAC equipment (e.g., a 94% vs. 90% efficient furnace), mastic sealer on all heating ducts, all Energy Star appliances, and 80% of lighting must be compact fluorescent or LED. A blower door test is required following construction to assure a maximum of 4 ACH50 (air changes per hour at 50 pascals). Ducts are also tested with a maximum acceptable leakage rate of 6%. The EPA also has complementary certification programs available for water conservation and indoor air quality.
The Earth Advantage New Homes program allows for different levels of certification (i.e., Earth Advantage Silver, Gold, or Platinum) depending on the number of points earned in each of five categories: energy efficiency, indoor air quality, resource efficiency, environmental responsibility, and water conservation. In addition to the score sheet, Earth Advantage requires two verification visits: the first during construction, to test for maximum moisture content in studs (where applicable) and assure proper installation of insulation and mastic application (among other things); and the second following construction, to conduct the blower door and duct leakage tests.
Leadership in Energy and Environmental Design (LEED) is a program of the U.S. Green Building Council. LEED for Homes 2008 is also a points-based program with four performance levels: Certified, Silver, Gold, and Platinum. There are 18 prerequisites (mandatory measures), certain minimum requirements, and a total of 136 points available in eight categories, including sustainable sites, location and linkages (such as proximity to services), and education and awareness. LEED for Homes adjusts point requirements depending on the home’s size, rewarding builders for smaller structures.
The 2012 ICC-700 National Green Building Standard (NGBS) is a program developed through a partnership between the National Association of Home Builders (NAHB) and the International Code Council (ICC). Certification under the NGBS can be achieved at four levels: Bronze, Silver, Gold, and Emerald. Points are earned in six categories: energy efficiency, water conservation, resource conservation, indoor environmental quality, site design, and homeowner education. The latest version of the NGBS requires energy-efficient performance to be 15% higher than the 2009 International Energy Conservation Code and includes new scoring opportunities for choosing lots in green communities, and for existing building projects, including a protocol for common renovations (e.g., kitchen, bathroom, or basement) or an addition under 400 square feet.
In contrast to other green-building certification programs, Passive House Institute US (PHIUS) has developed an ultralow energy building standard with the goal of a 90% reduction in energy consumption. It requires building design with a Passive House consultant and a PHIUS+ rater, who consider how to make the operational elements (e.g., cooking, lighting, bathing, etc.) of the home abide with the standards. At the end of a full year of occupancy, calculations are made to determine if the energy usage goals were met.