Innovative solutions for creating healthy, efficient, eco-friendly homes

Taking the LEED

Homebuyers no longer have to become instant experts to find homes with high efficiency and environmental performance. Certification labels like LEED (Leadership in Energy and Environmental Design) help consumers understand a home’s actual environmental content, and guide professional builders in designing green, efficient homes.
The LEED for Homes (LEED-H) program, officially launched November 2007, was developed through a rigorous consensus process and thoroughly pilot-tested by rating real homes. As of April 2008, more than 400 U.S. builders have registered with the program, representing the production of 10,000 homes. According to the U.S. Green Building Council, which developed the LEED-H certification program, more than 200 LEED-rated homes have already been completed, with many more on the way.

LEED-H is a point-based system designed to provide a well-balanced portfolio of energy-efficiency measures and green building products, many of which are hidden from view but are vital to balanced long-term performance. Examples include thicker insulation, air sealing, integrated ventilation, efficient plumbing runs, better mechanical equipment and increased recycled materials content.

Homes receive points toward certification in eight categories, including design, site stewardship, material selection, indoor air quality, and energy and water conservation. A total of 136 points are available under the LEED-H rating system, with a minimum of 45 required for certification. Homes that receive 60 or more points are rated Silver, those that receive 75 points or more are rated Gold, and those that achieve 90 or more points are rated Platinum, the highest LEED-H rating available.
Direct benefits of LEED-rated homes include lower energy and water bills; reduced greenhouse gas emissions; potentially less exposure to mold, mildew and other indoor toxins; and better resistance to obsolescence. In addition, the net costs of owning a LEED home will be comparably less than owning a conventional home. Green homes also benefit local communities with reduced infrastructure costs and lower pollution impacts.

To better explore the details of a LEED-certified home, we’ve focused on three certified homes in diverse regions of the country. As these three projects demonstrate, when purchasing a LEED-rated home, homebuyers can feel confident in their green investments.
Zero-Net-Energy Home
Arnika Subdivision
Esopus, New York
Builder: Anthony Aebi

Extensive solar design, super-energy efficiency, a healthy home ventilation package and locally milled timber keynote this high-performance home, which achieved a LEED-H Gold rating. Located in New York’s Hudson Valley, the four-bedroom, three-and-a-half bath, single-family home has about 4,500 square feet of living space.
The home achieves near-zero energy consumption with a well-balanced package of measures. As an indication of its efficiency, it achieved a home energy rating system (HERS) rating of 0. (For the HERS rating system, the lower the number, the better.) By comparison, an Energy Star-labeled home generally rates 85 (80 in colder climates) on the HERS scale, while a typical code-built home receives a rating of 100. HERS ratings for 1970s-era homes are typically in the 125 to 140 range. (See the sidebar for more information on the HERS rating system.)

Insulating concrete forms (a polystyrene shell into which concrete is formed) and spray-applied foam insulation were used for the home’s building shell. This approach lowers heat loss and greatly reduces energy-wasting air leakage. Due to the home’s airtight construction, an energy recovery ventilator (ERV) was installed to minimize indoor air quality concerns. A geothermal heat pump provides auxiliary backup heating and air conditioning. The geo-exchange unit also preheats the domestic water, boosting overall system efficiency.

The large photovoltaic (PV) solar-electric system provides a rated 15 kilowatts of peak power and is tied to the utility grid, so the homeowner can sell excess solar power back to the utility. In addition, the builder installed a low-energy lighting package and Energy Star appliances to further reduce electric usage. Green features include the use of lumber recovered and milled on site.

Several resource-efficiency techniques were employed at the jobsite. During early site development, rock excavated for the foundation was reused for retaining walls and landscaping elements. Construction waste was sorted for recycling, and leftover materials were mulched on site, minimizing landfill waste.

The cost for this home (less land) was approximately $133 per square foot, which indicates a negligible marginal cost increase in the southern New York region, when compared to a similar-sized conventional home. Green features added about $20 per square foot to first cost, equating to a 15 percent cost premium, according to the builder. However, the home’s overall cost appears competitive with conventional high-quality homes in the region, according to standard cost and data references.
Thompson Residence
Grand Rapids, Mich.
Builder: Insignia Homes

Controlling energy costs, creating healthy indoor environmental conditions and reducing the residential carbon footprint were key driving factors in the design and construction of this 4,900-square-foot custom home for a family of four. Built on an infill lot in a well-established neighborhood of Grand Rapids, the home, which achieved a LEED-H Gold rating, is within easy walking distance of many community resources, and adopted existing city infrastructure.

The project was guided by an IDP (integrated design process) team, which focused on a holistic approach to the building as a system. Among other goals, the builder wanted the home to utilize local/regional-sourced products, fit in with its neighbors architecturally and demonstrate innovative green technology, as well as highlight the fact that “green can be [both] beautiful and traditional,” according to the builder.

The builder reduced disturbance of the construction site through erosion control, and implemented a waste management program during construction. In addition, the builder planted native drought-tolerant species and installed a minimized irrigation system to improve water efficiency. Lawn areas are planted in low-mow turf, developed for drought resistance. The site also includes two rain gardens, which are designed to capture stormwater and reduce runoff.

The home is energy efficient, producing a HERS score of 46, which does not include a photovoltaic-solar system, for which the home was prewired. Air tightness was checked and improved using blower door testing. Thermal insulation employed a soy-based foam product with an R-value that is 5 percent higher than required by local codes. To economically reduce basement heat loss through the foundation, the builder opted for precast insulated wall construction.

The home’s advanced windows have 20 percent higher performance levels than Energy Star windows typically used in Michigan. Extensive window planning ensures natural lighting, as well as design integration with efficient electric lighting, occupancy sensors and dimmer controls. Compact fluorescent lamps (CFLs) further reduce electric power usage.

Heating and air conditioning are provided by a geothermal heat-pump system operating in concert with an ERV system to maintain healthy fresh air while reducing energy waste.

Since there is a chemically sensitive family member in the home, building materials were carefully chosen with respect to their impact on indoor environmental quality. Materials needed to be free of urea-formaldehyde, latex and PET (polyethylene terephthalate), and have minimal VOC (volatile organic compounds) emissions levels.
During design, the IDP team emphasized materials high in post-consumer recycled content. Sustainable materials were also selected with the home’s expected 150-year lifespan in mind, so durability, as well as functionality and low maintenance, were important. In addition, whenever possible, the builder selected materials that were locally or regionally sourced.

The cost for this home (less land) was approximately $202 per square foot, which indicates about an 11.5 percent marginal cost increase in the Grand Rapids, Mich., market, compared to similar-sized conventional homes.
Ecos Zero Energy Home
Sebastopol, Calif.
Builder: Paul Rosen, Ecos Builders

Designed in the traditional ranch style with passive-solar design features, this home is one of the highest-performing LEED-rated residential buildings in the country, and has the distinction of reaching Platinum performance levels. It achieved this rating by placing an emphasis on super energy efficiency and sustainable building materials.

The four-bedroom, three-bath, home has 2,600 square feet of living space in an efficient interior layout that minimizes wasted spaces and accommodates modern lifestyles. The home was highly integrated to the building site, so that it appears nestled into the hillside and takes advantage of solar energy and the prevailing winds.
The builder used efficient framing techniques to control wood waste, and integrated several components reclaimed from old buildings into the project. For example, stained glass reclaimed from a local 1840s storefront was used as accent glazing, and reclaimed 100-year-old local brick was used for the fireplace. In addition, recovered crushed asphalt and concrete materials formed the driveway. The framers re-used lumber cutoffs, and on-site recycling of leftover packaging materials greatly reduced landfill costs.

The builder stressed long-lived building materials to reduce maintenance and lifecycle costs, including natural cedar shakes, floor planks made from sustainable timber supply, low-emissions stains and paints, and natural wool carpeting.

The home’s design produced excellent energy performance, shown to be nearly 50 percent more thermally efficient than California’s tough Title 2 energy code. Wall, roof and foundation insulation levels were boosted and a roof-integrated radiant-barrier system protects the home from excess summer heat gain.

The floor plan was developed to emphasize natural ventilation augmented with an exhaust fan. The mechanical ventilation system operates in stages to provide fresh air based on actual conditions. The forced-air heating and cooling system employs zoned heat pumps, located to improve both winter and summer efficiency. Hot water backup heat is provided by an efficient gas-fired tankless water heater. All major appliances are Energy Star-rated high-efficiency units.

Renewable energy systems include both a solar water heater and a roof-mounted 4.7-kilowatt photovoltaic electric system, sized to offset remaining electric power needs. The HERS rating approaches the 0 level, since the solar water heater and PV electric system offset most electric power usage.

The cost for this deep-green home (less land) was $200 per square foot, which indicates about an 8 percent marginal cost increase in the North-coastal California market, compared to similar-sized conventional homes. Like the other two LEED-certified homes, it promises low energy bills, enhanced comfort and healthy indoor conditions for many years to come.