- Grant Street house
Most buildings leak air, and therefore heat, through cracks in their building envelope. We get cold in our leaky buildings and turn up our heaters to keep warm. The heat continues to leak out, and we continue to turn up our heaters, and on and on the cycle goes. In the end, we may as well be burning our money to keep warm. Our building systems clearly aren’t working as well as they should for us or for the environment, which begs the question: Why aren’t we doing more to change this trend?
Actually, some of us are. Slowly but surely, people are building Passive Houses that use around 80% less energy, while keeping us warmer and more comfortable than drafty, conventional homes do. But even this is not enough.
It is critical that Architects, designers and builders begin applying the Passive House Standard during the design stages of their projects. Just as engineers must predict how buildings will survive earthquakes, designers should be using energy modeling tools to predict the energy consumption of buildings before they are ever built.
One of the most valuable tools to emerge from the Passive House Standard is an energy modeling tool called the Passive House Planning Package (PHPP), which for years has accurately predicted the energy needs of hundreds of Passive Houses built in Europe.
It makes the most sense to design with Passive House concepts in mind in the design phase of a new building, when it is easiest to accomplish, however it is also possible to apply these concepts to existing homes if a major remodel is in the works. The key areas most important to achieving a Passive House are:
BUILDING ENVELOPE & AIR-TIGHTNESS: The strategy is to focus first on the building envelope so that it optimizes heat gains and minimizes heat losses. The insulation system should be continuous from the bottom of the foundation to the top of the envelope. A designated layer should be continuous from top to bottom in order to achieve air-tightness.
FRAMING: The framing system should conform to all the structural requirements and be designed using Advanced Framing Techniques that eliminate unnecessary wood members and replace them with insulation.
DOORS & WINDOWS: The specified performance of the doors and windows, and their installation methods, should be synchronized with the climate requirements, as well as the orientation and design of the building envelope in order to optimize heat gains and minimize losses.
VENTILATION: A ventilation system with a heat recovery component should be installed to circulate fresh air 24 hours a day, while transferring the heat from stale outgoing air to fresh incoming air. Free heat generated from lighting, computers, household appliances and people is recycled so we don’t have to blast our heaters to keep warm.
- heat exchanger graphic
After follwing these design and construction strategies, every building designed to the Passive House Standard is comfortable, sustainable, and requires far less energy to run than a conventional home. Our Grant Street home in Berkeley, CA was the first residential retrofit project in the US with the goal of meeting Passive House Standards.
Grant Street house AFTER