Based on design models established by Germany’s Passivhaus Institut, passive
dwellings basically heat and cool themselves, often slashing typical heating bills by upwards of 90%. Although more than 30,000 of these ‘zero-energy’ buildings have been erected in countries like Austria and Germany, passive houses remain rare in the United States; only 12 U.S. projects have been awarded certification from the Passive House Institute, the American arm of Passivhaus Institut.
Not to be confused with passive solar, which requires architects to calibrate their designs to maximize solar energy, passive houses focus on minimizing the amount of energy used to heat, cool, and operate a dwelling. Unlike more traditional green residential designs, which often rely on pricey technologies like solar panels and wind turbines, passive houses come close to achieving near-zero energy consumption by being super-insulated and airtight; a focus on old-fashioned building science to reduce energy use by up to 90% less energy.
To achieve this, builders insulate the entire envelope, including the walls, roof, even the foundation, and meticulously caulk, seal, and tape every possible gap or opening in the house so that the structure is so airtight it could literally hold water.
In addition to eschewing structural elements that might serve as thermal bridges (allowing hot or cold air to escape), passive design also relies on strategically placed windows to ensure the home gains more heat than it loses.
Last but not least, passive houses tap into the energy and residual heat (from, say, a clothes dryer or a pot of pasta cooking on the stove) that exist in the house through an advanced heat-recovery system; a “magic box,” the only mechanical equipment required in a passive house. It brings fresh air in and exhausts stale air and brings fresh air in, all the while transferring the heat to the new air coming in.”
And ‘airtight’ doesn’t mean you can’t open the windows; Passive houses operate like any other house. They’re just a lot more efficient.