There’s an old adage in the construction industry that your project can be fast, good or cheap- but not all three. If you want something delivered fast, and of excellent quality, it’s going to be expensive. The thinking is that the other variables will result in similar compromises, although in my experience you can really only have one of these choices on a given project.
It was in this context that a packed house at the Center for Architecture was regaled last week with multiple examples of seemingly impossible projects. Organized by AIA New York, New York Passive House, and Urban Green, the speaker was Gunter Lang, of Lang Consulting in Austria, and the subject was the innovative “Passive House” building energy standard. Following its strong record in Europe and the success of the first projects here in the US, Passive House is having a kind of breakout year. A conversation that for years has been restricted to a core group of committed believers has now broken into high level policy circles, with its inclusion in de Blasio’s climate action plan, One City: Built to Last, a high water mark for what had been a relatively obscure standard.
PASSIVE HOUSE BASICS
Passive House distinguishes itself from US energy codes at the most fundamental level- it is a performance metric. In the simplest terms, US energy codes only dictate the effectiveness of the components of a building (your boiler must have a certain level of efficiency, the materials in your walls, or your windows, must have certain resistance to heat loss), with the assumption that, taken together, these will add up to a building that provides shelter of an appropriate quality and doesn’t use too much energy in doing so. Whether they do or not is something of a mystery because US standards don’t require you to demonstrate meeting any efficiency goals post-occupancy. Passive House takes a very different approach, it requires that your building only use a very small amount of energy per square foot of space, and provides guidance on how to reach that target with a sophisticated modeling program. To achieve this, Passive House focuses on a few key issues:
- A highly insulated, unbroken envelope,
- Airtight construction,
- Continuous ventilation, and the
- Placement and performance of windows.
Without getting too deep into the building science weeds, by providing a building that doesn’t leak air (and therefore leak huge amounts of energy), is wrapped in heavy insulation (without the thermal breaks typical in US construction), is continuously providing fresh air, and has high performance windows of just the right size in just the right location, you produce indoor environments that are among the most comfortable available in the world and which use a fraction the energy of a typical building.
Lat week’s speaker, Gunter Lang, is among the foremost practitioners of the Passive House standard, having been the primary consultant on myriad projects and acting as the head of Passive House Austria. From this position he was able to present not just projects he himself has worked on but a host of projects by others, providing the audience with an impressive digest of high performance buildings, most of them remarkably beautiful.
The Passive House standard has now been successfully applied to virtually all major building types, from single family homes, to multi-story housing, to commercial and institutional projects. During his survey of these projects Mr. Lang pointed out some of the more promising aspects of the standard, chief among them the reliability of energy savings produced and the high quality of the interior environment provided for the occupants. Drafts, for instance, are virtually eliminated, due to the airtight construction and the high performance windows. It means you can wear a t-shirt and shorts in your living room in winter, and massively reduces the risk of moisture problems, like mold. Highly improved acoustics are another benefit. The tight envelope also insulates the interior from exterior noise (so no more sirens or passing car stereos waking you in the night), and because the ventilation system isn’t moving huge volumes of air around to temper leaky, poorly insulated spaces the system is silent. Not being able to hear the heating and cooling system, is actually a Passive House requirement. As a result, the experience of spending time in a Passive House is regularly described as zen-like- which, to take an example, is not how one imagines NYCHA residents typically refer to their surroundings.
The performance of these projects is otherworldly. While we hem and haw in the US about whether our buildings could be 30-40% more efficient (the typical province of LEED Platinum buildings), Passive House projects are routinely 80-90% more efficient than a typical US building. The energy use of a typical US office tower is often close to 200 kBTU/sf/yr. One of Lang’s new office tower examples uses 37 kBTU/sf/yr. Passive House appears to be the most viable means of our building stock contributing to the 80% reduction in NYC carbon emissions by 2050 set down by De Blasio.
BALANCING SPEED AND COST
So, the projects are good, even great. What about speed and cost? Surely these projects are absurdly expensive and surely all this attention to airtightness and eliminating thermal breaks takes an inordinate amount of construction time, right? Wrong. Apparently in Europe the fast, good or cheap- but not all three rule does not apply. In terms of construction time, many of the Passive House projects Lang presented were modular, with the project essentially built in large pieces in a factory, trucked to the site, and bolted together. This led to a series of projects which he described as having been constructed in a matter of days. 7 days. 9 days. 2 days! Each time he said this audience the guffawed to themselves, knowing full well a new building in the US would require months of on-site construction. And apparently this modular system produces buildings that are not only faster and better, but cheaper as well. Lang included construction costs for multiple projects, with many in the $150/SF range. These figures drew a lot of laughter from the audience since NYC construction figures are regularly closer to $300/SF in the outer boroughs and regularly north of $500 in Manhattan- with $1000/SF not unheard of. It left me wondering if there had been some sort of Euro to US Dollar conversion error. Setting aside the actual costs per square foot, many estimate the increased cost of Passive House projects in NYC at less than 10%, with the numbers expected to come down significantly as the industry learns about the standard and what it takes to meet these requirements.
Mr. Lang makes a fine apostle for a very promising standard. He’s technically astute and funny- while presenting a courthouse he noted that the politicians even approved funding for the prison cell wing to meet the Passive House standard, with the wry aside that maybe the politicians knew where they were heading and wanted to ensure a comfortable stay. I’m sure most of the audience left excited by the standard and the prospect that it might help ensure the construction of high quality, energy efficient buildings.
Along with many in the public and private sectors, BEEx will be exploring how the Passive House standards fits into the New York City real estate market. Of particular concern, is the applicability of the standard to the sort of piecemeal retrofit work (as opposed to full renovations) that dominates the market here. I’ll be visiting the Passive House international conference in Leipzig later this month to ask after these and other concerns and will report back on the implications for the many stakeholders that influence the success or failure of projects in the US.
– Yetsuh Frank