What the Passive House Standard Could Mean for Your Old House

Mary Butler

Is it possible to retrofit a 160-year-old home so that it requires no mechanical heating? A builder is trying to do just that in Boston using the Passive House standard, a German-borne set of energy efficiency principles dating back to the late 1980s.

"The Passive House approach is very techie, which I think is its Achilles Heel--it appeals to geeks but not the layman, the lay builder," builder Simon Hare told CNET News last month. "We can prove we can do this without hiring consultants and using software to do the energy modeling. We'll just use precedent and established rules of thumb."

His work serves as inspiration for other green old house remodelers, who seek to do away with high energy bills.

Passive House Standard: What Is It?

The Passive House standard is probably very close to what you're already trying to do with your own old house remodels. In a nutshell, you use insulation to create an air-tight building and outfit your home with energy-efficient appliances. Once you add "distributed energy" such as solar panels for hot water and electricity, you get close to net-zero energy use.

Hare, the Boston builder, has been able to create an especially tight building seal, in spite of his home's original construction, due to structural problems that required the home's frame to be rebuilt. You can too by using structural insulated panels (SIPs)--essentially plywood sandwiching 12-inch layers of foam insulation--and then tape or spray the home's building joints with more foam.

To further seal leaks, you can conduct blower-door tests. Hare used a borrowed dance club fog machine and was able to see where air slipped out and seal those holes. To create extra thermal mass, Hare poured concrete floors and interior walls.

If all this work sounds expensive, that's because it is.

Passive House Standard: Saving Costs in the Long Run

However, one way to cut costs is to use mostly recycled or inexpensive materials. And remember, with the Passive House standard, you won't need a mechanical system. Come winter, you may need to wear sweaters indoors, as the temperature inside a Passive Home doesn't generally go higher than a chilly 65. But you also won't need to turn on the heat. And in the summer, your home should stay cooler than most, thanks to the added insulation--and concrete if you decide to go that route.

To warm the home, you can open south-facing shades during winter days, and close them at night--and in the summer, you can simply open your windows at night to cool the building.

In the end, with the Passive House Standard, you can have a daily reminder of your lack of modern heating and cooling, but also a heavier wallet from your energy savings.

by Martin LaMonica z • This green home will heat itself • Jul 24, 2009 • http://news.cnet.com/8301-11128_3-10293753-54.htmlhttp://news.cnet.com/ • CNET

About the Author
Mary Butler is a Boulder, Colorado based writer and editor, who spends much of her free time remodeling an old house.

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