Dec 11, 2018 _ insights
Fur coats for buildings? Yes please.
“When it comes to buildings, the U.S. hands out windbreakers; Europe delivers fur coats.” When I heard a fellow designer say this during a presentation at the U.S. Green Building Council’s Greenbuild Conference, it got my attention.
If we’re serious about fighting climate change, we must design responsibly. Simple choices we make can reduce our buildings’ carbon footprints, make them more resilient, and provide a healthier, more comfortable environment for people. Becoming a certified Passive House Consultant was a way for me to bring deeper sustainability knowledge and skills to our clients’ projects.
Passive House (Passivhaus) concepts were originally developed in Germany in the 1990’s by building scientists interested in developing construction methods that set higher sustainability standards while simultaneously optimizing construction vs utility costs. For example: more is better when it comes to insulation, but only to a point. One could design a wall with three feet of insulation, but the cost of the additional materials probably wouldn’t pay for itself during the life of the building (Passive House guidelines actually suggest 12-18” of appropriate material).
Passive House principles have caught on in the US and not just for residential buildings; libraries, offices, community centers, and other public spaces can also benefit.
Passive House standards focus on five main principles:
- Continuous, thick, insulation
- High performance windows located to optimize passive solar energy
- Balanced, constant flow of fresh air
- Airtight construction
- Minimization of thermal bridging—spots where structural elements may transfer heat outside the building, see illustration below.
Incorporating all of these principles within a building design, makes a conventionally sized mechanical system unnecessary (some heating systems shrink down to the size of a hair dryer!). The additional costs of higher performing windows and thicker insulation are offset by much smaller mechanical systems, which continue to save on future operational costs.
There is no one-size-fits-all approach to Passive House design. Passive House US (PHIUS) emphasizes a geographic-specific approach that is tailored to the unique climate conditions within a 50-mile radius and 400-foot elevation of the project. There is no single best insulation material or detail to eliminate thermal bridging; architects can use the best, or most local, or most affordable materials, as long as they meet the same end results. Computer simulation programs such as WUFI and THERM allow architects to test out unique designs and make informed adjustments that impact successful performance. Additionally, PHIUS offers guidance and feedback during the design process. They also send raters to the site during construction to help ensure the project is being built as designed.
Saving-the-planet feel-goods are not the only benefits of Passive House design. Passive House buildings are more durable and less prone to mold and mildew. Their airtightness eliminates uncomfortable drafts or cold spots on interior surfaces, especially windows. The inside air is often described as “sweeter” due to the fact that airtight buildings help filter outdoor pollutants and constantly refresh and recirculate the air. The super-insulated walls and windows create an extremely quiet interior environment, which is valuable in noisy urban settings. During power outages, buildings are much more resilient in maintaining their indoor temperatures for significantly longer periods of time.
As climate change becomes a pressing reality, architects can make a positive difference by using knowledge and skills to help clients create facilities that are good for people and good for the planet.
Stephen is a registered architect and Certified Passive House Consultant at GBBN.