The goal of a passive house is to perform its mechanical functions passively – with as little energy input as possible. This approach to homebuilding minimizes a house’s ongoing impact on the environment, which is one way to live a tinier life. Here are the five principles that govern passive house design.
1. Insulation. A building envelope with high R-values all the way around keeps the indoor temperature constant, so it doesn’t fluctuate with the temperature outside.
2. Windows. Usually the weak points of a building envelope, windows in a passive house are typically triple-glazed. They’re positioned to maximize sunlight in cold months and minimize it in hot months.
3. Ventilation and heat recovery. A ventilation system provides continuous fresh air year-round. A heat recovery system transfers thermal energy from the outgoing air to the incoming air, preserving that all-important indoor temperature.
4. Air tightness. The building envelope has no punctures where air could leak. Even accidental nail holes are caulked closed during construction.
5. Full thermal break. Weak points where heat can transfer through the building envelope, such as continuous window sills, are known as thermal bridges. These are eliminated to maximize the effectiveness of insulation. A full thermal break between inside and outside also prevents moisture accumulation and protects against mold.
Some Passive House principles seem backwards at first glance. Doesn’t a ventilation system require energy to operate, while a drafty wall lets air pass through for free? My answer: ventilation doesn’t exist in a vacuum. (That’s an amusing tautology!) A drafty wall lets in so many things other than air – heat or cold, moisture, unwanted breeze – that a sealed house is considerably more efficient to operate. Up to 90% more efficient, if the Passive House Institute is to be believed.
Also, the thick insulation and HVAC systems only have a job to do when the air outside is radically different from room temperature. If you live in a passive house and you want to enjoy a mild spring day, it’s OK to open the windows!
A group of Norwich University students designed and built the CASA 802, a tiny house on wheels, for a semester program. (802 is the area code for all of Vermont, in case you didn’t get the reference.) The house won the 2016 People’s Choice Award from the Vermont chapter of AIA, America’s professional organization for architects. Now the 324-square-foot abode is occupied full-time by a Shelburne resident, meeting the program’s goal of helping the state’s low-income housing population.
Here are some of the house’s most impressive features. Plywood, flooring, and siding – virtually all the wood used besides dimensional lumber – is locally harvested and formaldehyde-free, minimizing the house’s embodied energy. Cellulose-filled walls, low R-value doors and windows, and high-efficiency HVAC systems further reduce the energy demands of a small house. The house was built for easy installation of solar panels, but they won’t help on the shady current site.
The AIA award reflects this project’s success in creating a comfortable house that fits in with local architecture at a low price point. I hope Norwich makes it an annual program.
Today’s action: sign this petition telling President Trump to act on climate change. Trump has stated that global warming is a hoax, and although he backpedaled during the campaign he has since revealed his true position by nominating leaders in the fossil fuel industry to his cabinet. “Protecting the planet” may not be a convincing argument for a businessman, but renewable energy can be less expensive and employ just as many people as the current system. To get there requires a global commitment and appropriate funding for research and development.
I’m not sure how effective an online petition can be to spark change, but this one is nearly 130,000 signatures strong, and it only takes 30 seconds to sign.
Building excitement for his upcoming workshop in Los Angeles, tiny house goofball spokesperson Deek Diedrickson is giving away an Envi, an slim electric wall-mounted convection heater. Envi claims it can warm 150 square feet, which could equal a large bedroom, a medium living space, or a small house. To enter, all you have to do is share this quick video on Facebook before 8pm EST today.
Today’s action: Call your senators and ask them to stop the confirmation of Scott Pruitt as the next Administrator of the EPA. Pruitt has said of global warming that “the debate is far from settled,” and as Oklahoma State Attorney General he has repeatedly sued the EPA to fight regulation of fossil fuels. Yesterday the Office of Government Ethics cleared Pruitt of any financial conflict of interest, and he now faces confirmation by the US Senate. Nominees are rarely rejected, but controversial picks often withdraw themselves.
You can look up the phone numbers of your senators here.
Sample script: Hello, my name is Scott Silverstein and I live in Waitsfield, Vermont. I’m calling to express my concern about Mr. Trump’s nomination of Scott Pruitt to head the EPA, because Mr. Pruitt’s history in public office shows a lack of concern for the environment and a disregard for scientific facts. For these reasons, I’d like ask Senator (Leahy, Sanders) to oppose this nomination. Thank you for your time.
Don’t be afraid to call. The interns who answer the phone are really nice.