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Green Homes

Luxury Home Earns Gold NAHB Energy Value Housing Award

Much of the native landscape was preserved when this house was built — a step that is especially valuable in such an arid region. In the southwestern United States, lawns and other non-native plantings severely burden local water supplies and displace delicate natural ecosystems.
Image Credit: Tony Grahame
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The pre-cast foundation was a great labor and resource saving choice.
Image Credit: Tony Grahame
Even in this relatively dry climate, the foundation still needs a moisture barrier. XPS foam boards protect the waterproof coating and add extra insulation.
Image Credit: Tony Grahame
The home has a thoroughly detailed drainage plane. RBT builders taped the housewrap seams and covered the walls with rigid foam insulation before applying stucco. A porous drainage mat covers the foundation waterproofing.
Image Credit: Tony Grahame
Ducts sealed with mastic keep conditioned air in and contaminants out, benefiting energy efficiency and indoor air quality.
Image Credit: Tony Grahame
In a successful air sealing strategy that required only a little extra effort, the builders caulked the framing before installing drywall.
Image Credit: Tony Grahame
Photovoltaic and solar hot water panels keep energy costs to a minimum.
Image Credit: Tony Grahame
Cellulose insulation and engineered framing and foundation components played a big part in the resource efficiency of this home.
Image Credit: Toshi Woudenberg

#Students’ Academic Pursuits Provide Real-World Results

This luxury house won an NAHB Energy Value Housing Award (Gold) while also complying with several sets of standards including LEED, Environments for Living, and ALA HealthHouse. It was designed to be healthy, durable, and affordable — as should be the goal of any sustainable building. Every detail was carefully considered, making the home efficient to build and live in.

Premanufactured components sped construction; thoughtful planning minimized site disturbance and preserved existing vegetation; meticulously installed insulation, a tight building envelope, and a rainwater collection system minimize energy and resource demands. Methodical preparation and execution are likely responsible for this project’s high marks, but something else also makes it unique – it was built by university students.

Hands-on learning
At Yavapai College, in Prescott, Arizona, the Residential Building Technology Program immerses students in both the theoretical and practical sides of high-performance homebuilding. Director Tony Grahame leads each class through every stage of design and construction necessary for the completion of a marketable home. The students learn not only about the necessary integration of a building’s parts, but also about the cooperation that is essential to make that building happen.

Good design and management, great house
Although its source of labor may be atypical, this project is a great example of how smart design can facilitate increased sustainability within a typical budget. Some of the methods and materials used might have been new to the RBT students, but the guidance they received gave them an edge over experienced contractors who don’t yet have green building training. This point was clearly made by an NAHB Energy Value House judge’s comment: “if only every house built in the U.S. could have the oversight of this project – all of our houses would be energy efficient and durable.”

Lessons Learned

In much of the country we  take our abundant supply of clean water for granted, but a growing number of homeowners have to think twice before they wash their car or water their lawn. Builders in the Southwest have been dealing with this forever, but pollution, climate changes, and development pressure could make this a big concern just about anywhere.

"Water could be the next expensive commodity for homeowners," says Tony Grahame. He believes a whole-system approach is necessary to make a real difference. Large rainwater catchment systems and separate grey water plumbing can eliminate the burden that landscape irrigation puts on municipal water supplies in this region, but efficient plumbing layout and low-flow fixtures are just as important. This is one place where a little planning can reap big rewards without much expense.

General Specs and Team

Location: Chino Valley, AZ
Bedrooms: 4
Bathrooms: 3
Living Space: 3202
Cost: 90
Additional Notes:

Student labor was free

Builder: Yavapai College Residential Building Technology Program; Tony Grahame, Director.
Architect/designer: Yapavi College architectural design students and staff

Construction

Foundation: combination - slab-on-grade XPS foam at edge (R-5), ICF crawl space (R-16), preformed foundation panels (Superior Walls) with blown-in cellulose (R-26.5)
Walls: 2x6 @ 24 in. o.c.; 2-in. XPS and 5-1/2-in. unfaced fiberglass batt (R-29)
Windows: double-pane, low-e, argon-filled (SHGC=.30 to .59; R 2.9-3.3)
Roof: dngineered trusses; blown-in cellulose (R-38)
Garage: thermally and pressure-isolated from living space

Energy

  • Whole-house Energy Star interior and exterior lighting package with CFL bulbs
  • Extremely tight building envelope (blower door test 0.96 ACH @50 Pascals)
  • Roof overhangs optimized for summer shading and winter solar gain
  • Energy Star appliances and fans
  • All ductwork located within conditioned space

Energy Specs

Heating/cooling: split AC system (46,000 Btuh, 14 SEER); dual-stage direct-venting gas furnace (56,672/80,960 BTU, 92.1 AFUE)
Water heating: solar domestic hot water (40.9-sq.-ft. panel, 80-gallon storage tank w/ backup electric)

Water Efficiency

  • Low-flow toilets, faucets, and showerheads
  • Water-conserving dishwasher
  • 1,250-gallon rainwater-collection system
  • Gray water distribution system
  • All hot water taps within 30 ft. of hot water storage tank

Indoor Air Quality

  • Balanced whole-house air exchange system with MERV-10 and HEPA filtration
  • All construction materials contain low or no VOCs
  • Low formaldehyde content in particleboard cabinets

Green Materials and Resource Efficiency

  • Decking, ICFs, wall, and ceiling insulation include recycled content
  • Cardboard and metal construction materials recycled
  • Precast insulated foundation panels
  • Advanced framing techniques

Alternate Energy Utilization

Photovoltaic: 2 KW
Solar water heating: 49.1sq.ft. panel, 80-gallon storage tank

Certification

NAHB Energy Value Housing Award: gold

2006 NAHB Green Building Award: Custom Home (Research) category

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