Luxury Home Earns Gold NAHB Energy Value Housing Award

Chino Valley, AZ

Sep 26 2008 By Rob Wotzak | 0 comments

General Specs and Team

Location: Chino Valley, AZ
Bedrooms: 4
Bathrooms: 3
Living Space : 3202 sqf
Cost (USD/sq. ft.): $90/sqf

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 XPSExtruded polystyrene. Highly insulating, water-resistant rigid foam insulation that is widely used above and below grade, such as on exterior walls and underneath concrete floor slabs. In North America, XPS is made with ozone-depleting HCFC-142b. XPS has higher density and R-value and lower vapor permeability than EPS rigid insulation. foam at edge (R-5), ICFInsulated concrete form. Hollow insulated forms, usually made from expanded polystyrene (EPS), used for building walls (foundation and above-ground); after stacking and stabilizing the forms, the aligned cores are filled with concrete, which provides the wall structure. 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-eLow-emissivity coating. Very thin metallic coating on glass or plastic window glazing that permits most of the sun’s short-wave (light) radiation to enter, while blocking up to 90% of the long-wave (heat) radiation. Low-e coatings boost a window’s R-value and reduce its U-factor., argonInert (chemically stable) gas, which, because of its low thermal conductivity, is often used as gas fill between the panes of energy-efficient windows. -filled (SHGCSolar heat gain coefficient. The fraction of solar gain admitted through a window, expressed as a number between 0 and 1.=.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

Heating/cooling: split AC system (46,000 Btuh, 14 SEER(SEER) The efficiency of central air conditioners is rated by the Seasonal Energy Efficiency Ratio. The higher the SEER rating of a unit, the more energy efficient it is. The SEER rating is Btu of cooling output during a typical hot season divided by the total electric energy in watt-hours to run the unit. For residential air conditioners, the federal minimum is 13 SEER. For an Energy Star unit, 14 SEER. Manufacturers sell 18-20 SEER units, but they are expensive. ); dual-stage direct-venting gas furnace (56,672/80,960 BTU, 92.1 AFUEAnnual Fuel Utilization Efficiency. Widely-used measure of the fuel efficiency of a heating system that accounts for start-up, cool-down, and other operating losses that occur during real-life operation. AFUE is always lower than combustion efficiency. Furnaces sold in the United States must have a minimum AFUE of 78%. High ratings indicate more efficient equipment. )
Water heating: solar domestic hot water (40.9-sq.-ft. panel, 80-gallon storage tank w/ backup electric)

Photovoltaic(PV) Generation of electricity directly from sunlight. A photovoltaic cell has no moving parts; electrons are energized by sunlight and result in current flow.: 2 KW
Solar water heating: 49.1sq.ft. panel, 80-gallon storage tank

  • Whole-house Energy StarLabeling system sponsored by the Environmental Protection Agency and the US Department of Energy for labeling the most energy-efficient products on the market; applies to a wide range of products, from computers and office equipment to refrigerators and air conditioners. interior and exterior lighting package with CFLCompact fluorescent lamp. Fluorescent lightbulb in which the tube is folded or twisted into a spiral to concentrate the light output. CFLs are typically three to four times as efficient as incandescent lightbulbs, and last eight to ten times as long. CFLs combine the efficiency of fluorescent light with the convenience of an Edison or screw-in base, and new types have been developed that better mimic the light quality of incandescents. Not all CFLs can be dimmed, and frequent on-off cycling can shorten their life. Concerns have been raised over the mercury content of CFLs, and though they have been deemed safe, proper recycling and disposal is encouraged. bulbs
  • Extremely tight building envelopeExterior components of a house that provide protection from colder (and warmer) outdoor temperatures and precipitation; includes the house foundation, framed exterior walls, roof or ceiling, and insulation, and air sealing materials. (blower door test 0.96 ACHACH stands for Air Changes per Hour. This is a metric of house air tightness. ACH is often expressed as ACH50, which is the air changes per hour when the house is depressurized to -50 pascals during a blower door test. The term ACHn or NACH refers to "natural" air changes per hour, meaning the rate of air leakage without blower door pressurization or depressurization. While many in the building science community detest this term and its use (because there is no such thing as "normal" or "natural" air leakage; that changes all the time with weather and other conditions), ACHn or NACH is used by many in the residential HVAC industry for their system sizing calculations. @50 Pascals)
  • Roof overhangs optimized for summer shading and winter solar gain
  • Energy Star appliances and fans
  • All ductwork located within conditioned spaceInsulated, air-sealed part of a building that is actively heated and/or cooled for occupant comfort.

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 VOCsVolatile organic compound. An organic compound that evaporates readily into the atmosphere; as defined by the U.S. Environmental Protection Agency, VOCs are organic compounds that volatize and then become involved in photochemical smog production.
  • Low formaldehydeChemical found in many building products; most binders used for manufactured wood products are formaldehyde compounds. Reclassified by the United Nations International Agency for Research on Cancer (IARC) in 2004 as a “known human carcinogen." 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 framingHouse-framing techniques in which lumber use is optimized, saving material and improving the energy performance of the building envelope. techniques

Certification

NAHBNational Association of Home Builders, which awards a Model Green Home Certification. Energy Value Housing Award: gold

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

Students' Academic Pursuits Provide Real-World Results

This luxury house won an NAHBNational Association of Home Builders, which awards a Model Green Home Certification. Energy Value Housing Award (Gold) while also complying with several sets of standards including LEEDLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. , Environments for Living(EFL). A green building program that focuses on building science to improve home energy efficiency and comfort. EFL is administered by Masco Contractor Services., 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 envelopeExterior components of a house that provide protection from colder (and warmer) outdoor temperatures and precipitation; includes the house foundation, framed exterior walls, roof or ceiling, and insulation, and air sealing materials., 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.


Rob Wotzak is assistant editor at GreenBuildingAdvisor.com

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Image Credits:

  1. Tony Grahame
  2. Toshi Woudenberg

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