What is a Passive House?
Save 90% of the energy of a typical house. Using off-the-shelf building products.
We became interested in the Passive House standard for a simple reason: today it is the only way to build affordable homes that meet the emissions goals of the Kyoto Protocol. While it is just starting here in the US, in Europe more than 20,000 homes, apartments, offices and schools have been built to Passive House standards.
How does it work?
A continuous air infiltration barrier wraps the entire building, making the house nearly airtight. Typical houses lose up to 40% of their energy through air infiltration.
2. Using the Sun
Maximizing south-facing glass takes advantage of the sun’s energy in winter. Deep overhangs over south-facing glass and shading for east and west-facing glass keep out the summer sun.
3. Super Insulation
With approximately R40 walls, R65 roof, and R20 floor slab continuously enclosing the entire building envelope, the house has more than double the insulation of a code-built house. Careful detailing of construction joints eliminates virtually all thermal bridging.
4. Minimal Heating and Cooling System!
All of this makes it possible to virtually eliminate the standard mechanical system. A simple energy recovery ventilator exhausts stale air and continuously brings in fresh air, exchanging heat and humidity between the two streams of air. The winter heating energy required is the equivalent of that of a hair dryer. Summer cooling and dehumidification is provided by one or two mini-split heat pumps.
What does it look like?
It’s not about style, but about how the building systems work and how it’s built. It can look like a house out of Dwell, or a Virginia farmhouse. Or an All-American foursquare —
This is a rendering of our Passive House project now under construction in Bethesda, Maryland. It’s the Washington area’s first Passive House. You can read more about the project on our Passive House DC blog.
Sounds expensive. How much does it cost?
The house we are building now in Bethesda will be about 8% more expensive in terms of bricks and mortar cost. That ends up being about 4-5% more in terms of total project costs. Projected monthly energy savings ($520), when compared to a conventional home, essentially offset the increased monthly mortgage cost. And those monthly energy savings are only going to go up as energy costs rise.
A multi-unit Passive House housing project now being built in Yellow Springs, Ohio was also priced both ways, and in that case, the Passive House construction came in at only 4.8% higher than standard construction.
How can I learn more?
Glad you asked!
- Read our Being Green Blog, especially What is a Passive House?
- Wikipedia’s Passive House definition thoroughly explains a number of Passive House terms.
- The Passive House institute US has good information on the standard and its spread to the USA.
- Our Passive House DC blog details construction of our Passive House now going up in Bethesda, Maryland.
What’s it like to live in a Passive House?
Here’s what the owner of our first Passive House says after living there for six months:
“We couldn’t be happier each time we walk into our new home. Not only is it beautifully designed and finished, but it always feels welcoming. Environmental comfort has been one the best surprises of the house—we are always more comfortable here with our thermostats set in the mid-60s than we were in our last house with the thermostat set to 72! And the utility bills have been less than half the cost of our previous, similarly-sized home. Perhaps most of all, living in alignment with our beliefs in preserving and protecting the natural environment is the best part of the house for us, something we are thrilled to share with our children in our everyday lives. From the high efficiency HVAC/ERV systems to the LED lighting, to the use of reclaimed and renewable sources of materials throughout the house, we’re proud to call it our home.”