If you follow the Green Building channel here at EarthTechling, you may have noticed a couple of trends recently. First, LEED certification appears to have infiltrated every corner of the building universe, and second, a number of other green certification systems are on the rise. A number of these certifications, such as Net Zero Energy and National Green Building Standard, were designed, in part, to build on the recognition for green projects that LEED has provided while pushing the green building envelope further.
Among the certifications we’ve been seeing more of recently is Passive House. No two ways about it: when it comes to energy use, Passive House is the most stringent building energy standard in the world. In order to gain certification from Passive House Institute US (PHIUS), a building must use 80 percent less energy than its conventionally constructed equivalent.
image via Sarah Evans
Achieving that kind of miserly energy use isn’t easy. In order to “maximize gains, [and] minimize losses,” Passive House-trained designers and builders make use of strategic design and planning; specific climate-based siting and sizing (to maximize passive solar heating and cooling); a super-insulated building envelope; thermal bridge-free detailing; an air-tight building envelope (with open diffusion); advanced windows and doors; energy recovery ventilation systems (to keep fresh air circulating in from the outside, without losing heat); and high efficiency mechanical systems.
We recently had a conversation with Sam Hagerman, President of the Passive House Alliance US, an advocacy organization focused on spreading the good word about Passive House and increasing the number of projects being built to this standard. Hagerman is also the owner of Hammer & Hand, Inc., a residential contracting firm with offices in Portland and Seattle that emphasizes sustainability in the built environment.
EarthTechling (ET): What’s your personal history with Passive House? How did you get interested in building this way?
Sam Hagerman (SH): In 2008 and 2009 my business partner, Daniel Thomas, and I decided to diversify our business more intentionally, including a new and renewed focus on high performance building. Although we’d been building sustainably since we began Hammer & Hand in 1995, I was worried about issues around high performance building and potential building failures such as sick building syndrome. Examination of those issues led me to Passive House, and I quickly understood that it was the most developed theory and method for planning and executing a truly high performance buildings. I saw its laser focus on energy performance as a bridge to a deeper understanding of building science. And that reinvigorated me as a building professional. In 2010 I was asked to become part of the Passive House Alliance US and have since been working on the national level to develop and grow this membership-driven organization to help promote adoption of the standard in the field.
image copyright EarthTechling
ET: How well known is the Passive House green building standard, and how much, would you say, is it being utilized?
SH: Passive House is a thousand times more well known than utilized at this point, at least in the United States. Worldwide there are about 10,000 projects certified and 30,000-40,000 built to the standard. In the US, just over 100 Passive House projects have been built, though hundreds are on the way. At least 25 projects, some multifamily, are under development right now in the Pacific Northwest. That’s for new construction. Retrofitting to the Passive House standard is much more difficult, and the grand total of completed retrofits in US numbers less than 20.
ET: Why, in your opinion, is there so much more buzz about Passive House right now than actual projects in the pipeline awaiting certification?
SH: Most architects know what Passive House is, and you hear a lot about Passive House standards in the [green building] news, but the reality of it is that there aren’t that many built units. It’s developing, and someday it will be a significant portion of the in-ground building market, but right now it’s just sort of an idea that’s percolating through everyone’s theoretical framework.
image via Beaton Construction
ET: What are some of the factors that have kept this standard, so far, from going more mainstream (such as LEED certification)?
SH: To build to the Passive House standard requires a real commitment to advanced building science and a modification of the procedures of building. Although standard construction techniques are often used in Passive House, they are used in multiple layers or in new ways that require technically precise design and installation. Passive House design also requires a Certified Passive House Consultant, or CPHC, someone trained in the Passive House Planning Package (PHPP) and the performance principles of Passive House. And that training is a lot more difficult to master than what’s required to become LEED accredited. So today there are far fewer CPHCs than LEED APs. To give LEED and the USGBC their proper due, they have done an amazing job at capitalizing on a green-hungry marketplace, and should be commended for their marketing ability and collaboration with industry and government.
But LEED doesn’t really represent a radical shift in how buildings are built. The reality of it is, [building to LEED] is fairly easy to do. [But] when you build a building that has a 90 percent reduction in its heat load, it’s a pretty radical endeavor. These buildings have much more thermally resistant walls — that means they’re often much thicker than a traditional wall assembly. The windows are triple-paned in this [Pacific Northwest] climate, and there’s great care taken in the assembly of the building shell to create an airtight layer. In Passive House building, we specifically at the blueprint level identify where the airtight layer is and include it as a separate line on the building cross-sections. So there’s great deal of specific planning going into how this air barrier is created and how it plays into construction.
There’s a lot more detail required. But it’s like anything else: the first one you do is kind of difficult, but once you get used to doing them that way, and you can’t imagine doing it any other way.
image via Digital Construction
ET: Are the associated costs higher than building to LEED Gold or Platinum?
SH: LEED Gold or Platinum are high performance enough to make them more expensive in that guise, but you also spend more money [simply getting certified] with those certifications. I’d say Passive House is cost-neutral as compared to LEED Gold or Platinum.
The number of Passive House projects are doubling every year. Our goal with the national leadership is to make Passive House cost-neutral to conventional construction. I don’t know if we’re going to get there, but we’re going to get damn close. And we’re certainly going to get close to [the costs associated with building to] Energy Star 3 or 4.
ET: How does the Passive House standard compare to the standard set by the Living Building Challenge (LBC)? Are they compatible/complementary?
SH: I see Passive House as a perfectly complementary and parallel path to Living Buildings. The LBC address all aspects of the built environment in a comprehensive way, beginning with a philosophically-oriented concept of land use and flowing through to the end goal: a building that gives back to the planet and its inhabitants.
ET: It seems that any project going for net zero or grid positive energy use would do well to adopt Passive House construction standards, since building this way minimizes the amount of energy that needs to be supplied via onsite renewable energy systems (which can be quite expensive).
SH: Definitely. It’s so politically incorrect to say “renewables are dumb,” but the truth is, they’re only [not dumb] if you have [already] optimized the building envelope. If you’re spending extra money on renewable power to heat an envelope that’s inefficient, or grossly inefficient, you’re just enabling poor building.
