A home that bridges the gap between mainstream and extreme green
The LEED for Homes pilot program was just getting started when Wright-Ryan Construction decided to build a spec house as a sort of green-building immersion course for its staff. Wright-Ryan invited Richard Renner Architects, a design firm with over a decade of experience in sustainable design, to help create what would become just the third LEED Platinum home in the country. Richard saw the project as both an opportunity and a challenge. Being a spec house, the design had to appeal the general public, but highlighting the sustainable aspects of the home was equally important. This balancing act went off almost without a hitch.
Trusted building details
Because they understood the challenge of constructing a durable, energy-efficient home in coastal Maine, they deferred to well-respected sources for guidance, including the research and publications of Building Science Corporation. This inspired some smart construction details, including offset headers and band joists that made room for rigid insulation and furred out siding that will dry more readily than if it were attached directly to the sheathing. The team also used a 24-inch framing layout, eliminated headers in nonload-bearing walls, and aligned rafters with studs and joists to keep lumber needs as low as possible.
Material choices demand just as much attention
Wright-Ryan and Renner didn’t stop at energy- and resource-efficient design – they also considered the source and health effects of their materials. Almost all of the lumber and trim materials were FSC certified. The few exceptions included locally harvested and milled wood flooring and Dakota Burl cabinet faces made from agricultural by-products. An equal concern for health called for easy-to-clean ceramic-tile flooring (containing recycled glass), low-VOC finishes and caulks, and a mechanical ventilation system.
Alternative energy should play a big role
Although the supertight building envelope is the foundation of the energy-efficient design (with an impressive pre-completion blower door test result of .12 ACH @ 50 Pascals), solar electricity, heat, and hot water are integral features. The metal roof supports a 2-kW, grid-tied photovoltaic (PV) system in one corner and three evacuated-tube solar collectors (with 30 tubes each) in the other. Solar hot-water collectors set to work well in the cold New England winters can create too much hot water in warmer months. The solar domestic hot water system is designed so that it can direct excess heat into the radiant heating system, which could help the house coast through the shoulder seasons. As a last resort or when the heating system is not in use, a branch of tubing that runs under the garage slab will safely expel whatever heat the house can’t use.
The home takes advantage of passive solar heating as well. The three south-facing dormers have properly proportioned roof overhangs that allow only winter sun to directly strike the upper windows. The same scenario plays out on the first floor, but in this case there’s a clever bank of louvered awnings providing the seasonal shade that prevents overheating in summer.
Keeping the outside green
Wright-Ryan took a conservative approach to developing the previously undisturbed wooded site. The company cleared only enough land for construction access and to ensure good solar exposure for the roof-mounted PV array and solar hot-water system. After completing the house, landscapers planted ferns, indigenous shrubs, and wildflowers – all purchased locally – over more than half of the disturbed area. The crew thoroughly mulched all landscape beds to aid water retention and add organic matter. They seeded the small remaining lawn with a hardy, low-maintenance fescue. For permanent access, Wright-Ryan put in a simple gravel driveway – the least intrusive option.
Richard Renner feels that the finished home measures up well to the initial stylistic, functional, and performance goals, but he might tell you that the big lesson learned is “go with your gut.” The original plan was to build a fairly modest home, but a real estate consultant advised the team that both the site and the market warranted something larger. It probably didn’t help that the housing market was starting to slip, but by the time the place was ready to sell, buyers interested in a 3200 square-foot green home were scarce.
On the brighter side, the staff at Wright-Ryan quickly realized that the project was invaluable as an educational resource. It successfully served its original purpose as an in-house training exercise, but the benefits spread to more people than anticipated. Subcontractors and suppliers were challenged to try new things and set higher standards; local and regional organizations were exposed to new ideas; and countless students were given a first-hand look at sustainable home building in action.
General Specs and Team
Foundation: 4-inch concrete slab, ICF walls (R-23)
Floors: 9-1/2-inch I-joists at 24 in. o.c.; 5-1/2-inch formaldehyde-free fiberglass batts between (R-21)
Walls: 2x6 studs at 24 in. o.c., dense-pack cellulose insulation (R-21)
Windows: Fiberglass frame, triple-pane, argon filled, low-e (U-factor=.15, R-6.7, Thermotech)
Roof: 9-1/2-inch I-joist rafters at 24 in. o.c.; loose-fill cellulose in ceiling (R-49)
Garage: Attached; ventilation fan activated by garage-door openers
- Majority of lighting fixtures are fluorescent
- Excess solar hot water assists radiant heating system
- Building and window oriented for passive solar heating, daylighting, and ventilation
Heating/cooling: evacuated-tube solar hot-water supplemented by high-efficiency propane boiler (Buderus); closed combustion fireplace for backup heat; HRV (Lifebreath); no air conditioning
Water heating: evacuated-tube solar hot-water system supplemented by high-efficiency propane boiler (Buderus)
HERS index: 42
Annual energy use: Home unoccupied—data to come
- Low-flow showerheads, faucets, and toilets (Mansfield EcoQuantum dual-flush)
- Drought-resistant turf
- Indigenous plants
Indoor Air Quality
Green Materials and Resource Efficiency
- FSC-certified lumber
- Advanced framing techniques
- Wheatcore doors, Dakota Burl cabinet panels
- Recycled-content floor tile
- Fly ash in concrete
- Recycled-content metal roofing
- Cellulose insulation
- Locally sourced birch flooring, stair parts, framing lumber, cedar siding, and granite countertops
Alternate Energy Utilization
PV: 2-kW, grid-tied
LEED for Homes: Platinum (95/130 points)