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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

Posted on May 9 2013 by Scott Gibson

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.

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Image Credits:

  1. Tom Marsik

May 9, 2013 1:50 PM ET

by Soylent Green

Spartan, but spiffy.

May 9, 2013 3:35 PM ET

More than $280 per sq ft
by But Why?

and you can put the whole thing in my kitchen&living room. How much do they pay for energy that they can save $4000 on costs on a 600 sq ft home? I don't live in Alaska but I am in a zone that requires slightly more heating than cooling days and my entire energy bill (heating, cooling, hot water and all other energy uses) is only $4800 for a year in home that is SIX times the sq footage of this (and we have 8 people in the family taking baths everyday/ generating 8 - 10 loads of laundry every week)

May 9, 2013 3:40 PM ET

Response to But Why
by Martin Holladay

First of all, construction in Alaska costs more than in the lower 48.

Second, the house has triple-glazed windows with fiberglass frames.

Third, this is a house-within-a-house. Did you see the reported R-values?

Fourth, you spend $4,800 a year on energy? Ouch!

May 9, 2013 5:51 PM ET

Heating in AK
by Dana Dorsett

Almost all non-wood heating in AK is done by resistance electricity or heating oil at a per-unit cost some multiplier of lower-48 average pricing. It's too cold to use heat pumps, and the natural gas grid isn't huge. Dillingham may have a comparatively temperate +15F mid-winter mean temp compared to the interior, but it's 99% outside design temp is in the -25F range and the heating season is 12 months long (yup, all year long, save a random handful of summer days!), with something on the order of 10-12,000 heating degree-days. At $5/gallon heating oil and a heating season like that it really adds up!!dashboard;a=AK/Dillingham

Seriously, " only " $4800 in annual energy bills? For a 3600' /8-person occupancy house, in roughly heating/cooling balanced climate- what's with that? It sounds like maybe a propane-heated 1978 code-min tract house in Macon GA (~2300HDD to ~2100 CDD) with a LOT of window area? An energy bill that big has a serious efficiency-upgrade budget to work with, and it's highly likely that it can be cut substantially with cost effective measures! (eg: If you have 8 people taking daily showers, a drainwater heat recovery heat exchangers would pay off in very short years. Air sealing & duct sealing will usually pay off in very short years too. I'm sure there are other higher-cost retrofits with longer term but still cost effective efficiency upgrades that can be taken too- houses are never really "done".)

My point of reference is my 2400' (+ 1500' semi conditioned basement ) sub-code 1923 antique, paying ~18cents/kwh and ~$1.15/therm gas, in a climate with about 6900HDD/350CDD, and my energy bills are less than half that. The occupancy is only 3 persons, true, but even adding for the extra cooling & bathing of 5 more sweaty bodies I couldn't come close to those kinds of numbers without leaving some windows open. We may be paying more per person, but since most of it is heating & lighting, the marginal costs per person or the slight uptick in fully conditioned floor area wouldn't make THAT much difference. (If I fully heated & cooled the insulated but not actively heated basement it would only add another ~$100 to the bill, if that.)

May 9, 2013 7:49 PM ET

Which HRV did they use?
by Eli Madden

Does anybody know which HRV they used?

May 9, 2013 11:15 PM ET

Dillingham has an average of
by David Northup

Dillingham has an average of about 11,333 HDD's. With heating oil likely over $6 or $7 per gallon and not to mention electric costs at likely $0.20 KWH - one can get to $4000 pretty quick in rural AK with a "normal" house.

I had the pleasure of doing a little work on this house a few years back when they were building it - Tom and Kristin put this thing together with the detail of a surgeon; as it shows in the blower door test.

Not sure what HRV they used; but Tom is the HRV guru and I am sure one of them will pop in and let you know.

Total cost I am sure does not include transportation costs which is another story in rural AK.

May 14, 2013 2:58 PM ET

2 for 1
by Mike Collignon

So if we all follow suit, we'd need to build two houses each time we want to build one. That certainly takes the sustainability discussion in a different direction.

May 15, 2013 5:37 PM ET

Edited May 15, 2013 5:39 PM ET.

Other than
by Dan Kolbert

the foundation, roof, siding, doors and windows, interior finishes, flooring, appliances, fixtures, drywall, mechanicals, painting - you're right, Mike.

May 15, 2013 6:00 PM ET

by Mike Collignon

Should have said, frame two houses.

If this methodology takes off, I guess I should invest in lumber futures. Chop, baby, chop!

May 15, 2013 6:25 PM ET

Congratulations to all
by Brian Knight

Congratulations to all involved! Ive always wondered who, where and what could make the claim.

As for the 600 sqft, is that interior dimensions? An exterior footprint of that size might see close to 200 sq ft disappear with walls that thick.

May 15, 2013 8:07 PM ET

no time for aesthetics
by Todd Stanley

So, all this time and energy spent to make the building energy efficient and zero time spent to make it visually appealing? The appearance of a building also contributes to its longevity; how many homely buildings do we see still standing in this country? The next owner may consider it ugly and just tear it down without taking a moment to consider its energy efficiency. Hire a designer to help.

By the way "But Why", OMG, sounds like your family needs a lesson in reducing consumption.

May 15, 2013 9:37 PM ET

by Marc Bombois

Great achievement, but the cost is a little high and I don't mean dollars. With all respect, from the one interior photo you'll never catch me living my life in a place like that. As we know, esthetics and ambience are extremely important for humans. A few more photos of the interior would be helpful but I doubt they'll dispel the feeling of confinement.

May 15, 2013 11:40 PM ET

A home only a building scientist could love
by Christopher Hall

Fascinating experiment for the minimalist in me but I could never live in a home like this year round.
Not surprising that the lights are consudered a heat source as they are going to be used a lot with only three windows.
I get the feeling this project was more about a world record envelope than building a home that adds value to the GB community.
Perhaps it's the way the price is written.
Maybe I just don't get it; but for me, this home is definitely NOT where the heart is.

May 16, 2013 6:57 AM ET

Response to Todd, Marc, and Christopher
by Martin Holladay

Todd, Marc, and Christopher,
It's an Alaska thing. I get it.

When the sun barely rises above the horizon for a few months every winter, and when the temperature outdoors is -50 degrees F, and when heating oil costs $5 a gallon, a house like this starts to look very much like a haven and a home.

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