“From the beginning—2003, for me—many very capable people challenged whether a single performance target for all climates made sense. But the notion of a single metric was, and is, very attractive. There was only one way to find out. To date, PHIUS has used the single metric for certifying projects in our PHIUS+ program.
We learned two things. One: passive building principles work everywhere. Two: when it comes to the metric itself, the skeptics were correct.
In places like Minneapolis, the community finds a disincentive; the amount of insulation necessary to meet the standard is prohibitive. In California, we had the opposite experience: it was comparatively easy. People could build largely the way they would have anyway with some additional efforts but didn’t save as much as they could have. That’s not what we want, either—we want to optimize energy savings in each zone.
We are taking a fresh look at what “optimal” means in a Passive House, accounting for climate and other differences. We partnered with Building Science Corporation. We have a standing technical committee of experts from across the country and disciplines. And we have lots of data accumulated over years of evaluating projects across the country.
We also took a look at tools. We originally used the European tool, a giant Excel spreadsheet that focuses on average data to model energy consumption. But in more extreme and variable climates, we need a more granular tool to tell us accurately how the building will perform, whether it’s comfortable, and how much energy it will consume.
We worked with Fraunhofer IBP to develop WUFI Passive, a software program that allows us to use hourly data for our models to predict how a building will behave. We are using the European metric as a baseline and running computer simulations to optimize the standard by climate zone. First results are both fascinating and exciting.
We expect that it will make sense to update the standards periodically, which is logical, given advances in materials and energy generation and changes in climate. I believe the community will be convinced by the science behind our proposal when we present it. In my opinion, it’s a no-brainer, but change is always hard. It was hard to get people to give passive building a shot in the first place.
The more we learn, the more we’re able to see the next step. We’re very eager to take that step, and we think the community will be too.”
Katrin Klingenberg presents PHIUS’s proposed climate standards at the 9th Annual North American Passive House Conference at 10:30am, Friday, September 12th, at the San Francisco Airport Marriott Waterfront. Klingenberg is the executive director of the Passive House Institute US (PHIUS).