Meet the Tightest House in the World
An Alaska couple sets a world mark with a blower-door test result far below the Passivhaus standard
A Dillingham, Alaska, couple has claimed a world record for airtightness in a 600-sq. ft. home with 28-in. thick walls and a ceiling rated at R-140.
According to the World Record Academy, a blower-door testTest used to determine a home’s airtightness: a powerful fan is mounted in an exterior door opening and used to pressurize or depressurize the house. By measuring the force needed to maintain a certain pressure difference, a measure of the home’s airtightness can be determined. Operating the blower door also exaggerates air leakage and permits a weatherization contractor to find and seal those leakage areas. measured 0.05 air changes per hour at 50 pascals of pressure (ACH50), less than 10% of the very rigorous PassivhausA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. air-tightness standard of 0.60 ACH50.
The owners are Dr. Tom Marsik, an assistant professor of sustainable energy at the University of Alaska at Fairbanks' Bristol Bay Campus, and his wife Kristin Donaldson.
The blower-door test was performed on March 6. Witnesses included Dillingham Mayor Alice Ruby and an analyst with the Building Performance Institute who called the results "phenomenally low."
Efficiency on a very small scale
The two-bedroom, one-bath house is insulated mostly with cellulose and is designed to be comfortable without a conventional heat source. Most of the heat comes from lighting, appliances, body heat and solar gain. The house needs the equivalent of 35 gal. of heating oil a year.
"If society acknowledges the importance of reducing energy consumption, a logical question to ask is: What good does it do to increase the energy efficiency of homes if it is outweighed by escalations in their size?" Marsik wrote in a description of the project in Alaska Building Science News. "The main purpose of this project is to demonstrate that by combining super-efficient construction technology with small house size, an extremely low energy home can be achieved."
Marsik said the house was built with a "double-frame technique" that included a continuous vapor barrier and both cellulose and fiberglass insulation. "The basic idea is simple," he wrote. "Build a small box inside a bigger box, seal the small box in a plastic bag, fill the whole cavity between the boxes with insulation, and you will end up with a supertight and superinsulated structure.
Other building features included:
- A heat recovery ventilator
- Triple-pane, 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 windows with fiberglass frames.
- 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. appliances and compact fluorescent lighting.
- Low-flow plumbing fixtures.
- All-electric operating, with no oil, propane or wood fuel.
Marsik says the extra insulation in the house cost $20,000, but he and his wife will see more than $4,000 in annual savings based on current energy costs. Total construction costs were $169,500.
- Tom Marsik
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