INHABITAT NYC: Passive House certification requires a diligent, strict following of the guidelines, to achieve specific performance standards, so it’s not a point-based scale such as LEED. How does it compare to other sustainability standards? How is PH advantageous in relation to LEED or in conjunction with LEED?
Ken Levenson: It’s great to use a combination of Passive House and LEED. The strength of PH is that it’s very narrowly focused on the energy requirements and has the counter-intuitive benefit that by focusing very strictly on the energy usage you end up with a building that has a lot of good qualities about air quality and thermal comfort. But Passive House is really about energy, while LEED and other sustainable design certifications can cover a wide range of things from land use to water use to toxicity of materials — Passive House does not address those issues. Certainly the people that are inclined to participate in PH are concerned with overall sustainability, and it goes hand in hand with the goals of Passiv Haus standards, so the less toxic a house, the lower the embodied energy of the construction. These are all good things, but not required for the certification. Passive House is really a nice complement to what LEED has been doing, and it’s not in competition with it.
The main difference, though, is that PH is an absolute standard. There’s no baseline energy modeling, there’s no saying “in comparison” or “this building type.” Pretty much any building type, anywhere has to give an absolute number. It gives the person trying to build to a Passive House real clarity. It’s pretty black and white, in terms of whether you’re making certification or not. And most prospective Passive Houses are not getting certified.
INHABITAT NYC: If you’re a client or a builder of a Passive House project, wouldn’t you think twice about investing in certification if it may not be achieved?
Ken Levenson: The project still benefits from using certified consultants and striving for building certification, for a few different reasons. Principally because once you’re certified, if you know what you’re doing, as long as you’re building to the methodology, getting the air tightness, getting the insulation levels, using the PHPP, the building certification isn’t really giving you a benefit. But for the early projects, I think it’s particularly useful to get certified, and certainly like LEED, when you have developers in projects, they’re looking to the certification as a gold standard to then take to the public and use to sell property.
INHABITAT NYC: I understand that it’s not necessary to create a Passive House certified building to achieve great energy efficiency. But if a client were to want that certification, to renovate a house into a PH, would one need to use one of the architects listed on the website and/or Passive House certified, or could the client bring in the design and construction team of his or her choice?
Ken Levenson: Yes, absolutely. Passive House is open source to a certain extent. You have to use the PHPP software, which is $150, but anyone can use it. It’s a lot easier if the person that’s using it is taking the certified training and gaining those levels of experience. You can use any building components in passive house construction, you can do any type or use of building to passive house standards, it can be any shape, any style. But to make life easier in terms of hitting the passive house standard, it’s easier if you use certified components, it’s easier if the shape is simpler. So you can definitely bring in any design team, but in terms of the website and passive house, there are people listed that are certified consultants, that work with architects, that work with homeowners, and then there are contractors that are certified. The client can bring those pieces together in any number of ways.