Our builder, Ted Clifton, just finished his latest house in Leavenworth, WA. We were disappointed that we had to miss the housewarming party, but from the photos, it looks really cool.
Unlike our net-zero-energy house, this new one follows the stringent Passive House standard, developed in Europe.
The hallmarks of a Passive House are super-high levels of insulation, a design that takes advantage of passive solar gain, and, as a result, has little need for heating beyond that provided by the sun, warm bodies, and appliances. Passive Houses also come with a list of requirements, like a heat recovery ventilator, a somewhat costly piece of equipment that recoups some of the energy that would normally be lost from circulating fresh air through the house.
Are Passive Houses better than net-zero houses? It depends who you ask.
We opted for the net-zero approach because producing as much energy as we used over the course of a year was our first priority. Passive Houses can be net-zero, too, but it’s not required by the standard, and it adds to the building costs.
The focus of Passive House design is to reduce the amount of energy required to heat and cool the house (by up to 90%), whereas the focus of a net-zero house is to offset 100% of the power required to heat, cool, light, and run the home. In any given moment, a net-zero house like ours might be using slightly more power than a similarly sized Passive House, but it would make it all back from its solar panels over the course of a year.
Passive Houses tend to cost more to build since they have even more insulation than a typical net-zero house. Critics of the PH standard point to diminishing returns. To chase after that last little bit of air tightness and insulation to bring a house up to the Passive House standard can be expensive, and, in many cases, the potential energy savings could be easily and much more cheaply attained by adding a few solar panels.
On the other hand, Passive Houses are elegant in the simplicity of their mechanical systems. Some of them require so little auxiliary heat that they can be warmed solely by a cheap little wall-mounted electrical heater, eliminating the need for costly heating systems. Proponents of Passive Houses point to the fact that mechanical systems eventually wear out and solar panels stop producing as much power over time, while a well-built, well-maintained house can last hundreds of years.
During our first winter in our house, we spent a lot of time tweaking the radiant heat system, and our heat pump required a replacement electrical board (under warranty, but still a hassle). The reality is, however, that many Passive Houses, especially larger ones in colder climates, also make use of heat pumps. And, if you’re interested in achieving net-zero-energy, you’ll need to install solar panels and an inverter on your Passive House.
Looking back on it, we wouldn’t have turned down the extra insulation the Passive House standard calls for, but not if it had required us to have smaller windows or forgo our net-zero-energy goal. By not strictly limiting ourselves to the rigid standard, we were able to achieve net-zero much cheaper.
Either way, both types of house save lots of energy, and I’m happy to see them being built. Plus, Ted’s newest project is just plain cool. Check out the sliced-off boulder table in the middle of the room!