Boulder, Colo.–based McStain Neighborhoods is trying to change the perception that building green is too expensive for the average production home builder. As part of its effort, the company is building a demonstration house in Loveland, Colo., that will be a testing ground for new building concepts.
“We want to see how well a house will perform if we make the building envelope as tight as it can be,” says Jeff Medanich, superintendent of special projects at McStain. The company also wants to see what techniques can be incorporated into its operation.
Discovery House is a 2,500-square-foot, three-level home with a 750-square-foot finished basement. The four-bedroom house, scheduled to be completed in May, eventually will be sold to a buyer willing to participate in a two-year monitoring and data collection program. The monitoring program aims to determine how an energy-efficient home performs in the real world.Fully Loaded
McStain is using a combination of advanced framing techniques and new-product innovations to achieve energy efficiency, moisture resistance, low-energy cooling, and healthy indoor air quality.
Outer walls are being framed with 2x6s that are spaced 24 inches on center, and the cavities will be filled with blow-in cellulose insulation. The skeleton will be sheathed in 1/2-inch oriented strand board and 3/4-inch rigid foam board insulation. “The foam board increases the R value of the wall by 5,” Medanich explains. “And the 2x6 allows us to use less lumber and provides more space for insulation.”
As an added measure of protection, the foam board will be covered with Benjamin Obdyke's Home Slicker, a three-dimensional nylon matrix that drains any moisture that infiltrates the fiber-cement siding.
Super Wall: The Discovery House's walls are constructed with 2x6 cellulose insulation, 1/2-inch oriented strand board, 3/4-inch foam board, a nylon matrix moisture barrier, and fiber cement, making it extremely tight, the builder says.
Credit: Courtesy McStain Neighborhoods
A house this tight could potentially have indoor air quality problems, but the builder will install an energy recovery ventilator that periodically brings fresh air into the house. Ceiling fans in every room and two whole-house exhaust fans will further increase circulation and will reduce air-conditioning use. Low VOC finishes that do not off gas will contribute to fresher air in the house.
Other features of the house include solar panels, radiant heating, and a 19.2 SEER air conditioner for extremely hot days. Cabinetry will be made from wheat board, and the garage will have special exhaust fans. “Attached garages allow air infiltration into the house,” Medanich explains. “But the exhaust fans will kick on automatically once the doors open. This will prevent air infiltration and car exhaust fumes from entering the main house.”
Once the house is sold, strategically placed sensors will record information such as how much energy is being used and the number of times the HVAC system cycles on. Medanich says that the project is important to the company's goals of green building, but he says the results could be even more important to the building community from a fiscal perspective. “Any custom builder can do anything once, but what [green building techniques] can you do over and over again? We want to find out.”