Wednesday, February 16, 2011
At last week's Better Building by Design Conference hosted by Efficiency Vermont I saw a handful of presentations showcasing Passiv Haus projects and their innovative design process as well as other super low energy net zero possible homes and projects. I learned there is a little bit of controversy for some reason going on now in our community between engineers, architects and building scientists about how low is too low or over the top excessive in home design and performance. And finally, how can Passivhaus and low energy/ net zero home design early adopters help move the residential marketplace toward a more positive energy efficient and resource conserving position? How can they replicate and expand the learning and experiences upto a community and regional scale? That's what it's all about. How we can help soften the hard landing for coming generations Bill McKibben lately of the book Eaarth forecasts in our coming shared future? Well I now have a deeper understanding, albeit brief, of many of the issues at hand and passions uniting them. And yes, there are some answers and there is hope.
What did I see and hear then...?
One was a renovation of a not so historic early modern Connecticut home designed by Ken Levenson of Ken Levenson Architects, P.C. Another was a Habitat for Humanity home designed by J.B. Clancy of Albert, Righter & Tittmann Architects, Inc. who designed it in collaboration with Peter Schneider from VEIC (the mother company of Efficiency Vermont) and Preferred Building Systems out of Claremont, NH. I also attended a spectacular presentation by Marc Rosenbaum from South Mountain Company, a noted energy design consultant here in the northeast and Building Science Corporation's Kohta Ueno who did a great job standing in for John Straube who was unable to be there last week. They started out as if they needed boxing gloves (actually not really...they're very kind and balanced engineers) but in the end there was much more agreement than consternation.
Where do I start...
Well, maybe I'll start with the bottom-line. Everybody's right! But here for starters are the ballpark super insulation level (...pre PHPP analysis) recommendations for Passivehaus projects in our cold climate region. They are R50-90 for roofs, R40-60 for walls, and R30-50 for sub-slab insulation. Windows are R7-10. They have extremely air-tight construction requirements needing to meet or be below 0.6 ACH@50CFM. High efficiency heat recovery systems need to be installed with supply to rooms with return air back. Then, less reliance on radiant slab space heating but rather heating of the ventilation air with other delivery methods. This is paraphrased from the BSC Insight white paper 025 and notes from the presentation. In the written piece John Straube wrote an in-depth comparison between the Passive House Standard and other low-energy homes BSC has been involved with recently. While at the conference, Kohto didn't go into super detail as the piece did but tell us the general insulation levels of the typical low-energy homes BSC is involved with. According to the paper such houses "consume 40-60% greater more energy than Passivhaus but are more cost effective". (Cost-effective meaning likely first costs to build and the return on investment over the long-term). They follow the BSC 5/10/20/40/60 building enclosure insulation recommendations. R5 for triple glazed low-e windows, R10 sub slab insulation with R20 in conditioned spaces in basements, R40 above grade walls and R60 for roofs. For BSC buildings backed buildings insulation is installed on the outside of the framing. Like Passivhaus, air-sealing is fairly stringent at 3 ACH@50 Pa with some homes able to come in at half of that with additional detailing care.
When adopting either of these approaches one challenge to design homes is the very low air-sealing requirements both standards lead to towards simplifying building shapes and overall building form. Unusual building shapes and variations in form, extra dormers, various ins and outs of buildings faces complicate air-sealing detailing and construction and increase construction costs. So building designers must be more creative working with simpler shapes and form factors. Another challenge is the need to limit the amount of window area in ratio to wall area. For Passivhaus' its not uncommon to have 9% on south faces and 1-3% window to wall ratios on other faces dramatically limiting daylighting into spaces and views from rooms to the out of doors. The low-energy homes designed from the BSC perspective allow for a bit wider flexiblity in the window to wall ratios. Andy Shapiro, of Energy Balance, Inc., a Vermont based energy consultant who's helped engineer and design many low energy homes, says plan for 10-15% window to wall area on the south and do as minimal as possible function specific glazing on the other walls faces.
This controversy is healthy for our industry and helps liven up the discussion about the need for this kind of design and what's right ultimately for consumers and productive for the planet. What everyone's disagreeing amicably about is degrees of difference in levels of insulation and how far to wean homeowners from fossil fuel driven energy sources in homes and our communities. Marc Rosenbaum, who wears many hats as an energy consultant, is a certified Passivhaus trainer. In his "How Low can you go part of the presentation" he was largely singing the praise of the system as a means to the end of getting architects, engineers and builders to really learn how to design better more high performing sustainable homes. He cares much less for the Passivhaus designation but emphasized the power of the excitement and learning he's watched transform professionals and the communities they work in when using it.
Marc framed this discussion at least from his perspective by saying "its important to consider that what is cost effective changes when you consider the big picture. It's not all about economics, but can be about our (shared) humanity. " He quoted David Ward (an author he read who I can't find more info on...help Marc?) who said "Focusing on energy and climate change is a moral issue not only an economic issue today." He also applauded the profound impact Joe Listiburek, the founder of Building Science Corporation has made on the building design and engineering community. It's inarguable Joe over the last 20 or so years really helped frame the discussion about building science and energy efficiency and brought it to a wider audience. He is forever grateful to him. As I am and many others around the country.
Marc applauds how Building Science Corporation has recently updated and increased the stringency of its insulation recommendations for building enclosures, especially in the northeastern cold climate zones. A good thing in his mind is how the presence of the Passivehaus standard perhaps helped push BSC to adopt the heavier insulation levels, tighter air-sealing standards and extremely low U-factors for windows. Building Science Corporation and its Build America program is closer to the production home building industry and higher volume production, ie closer to the mass marketplace for housing. Upping the insulation standards, doing better air-sealing and using better windows is a great thing! There are degrees of payback and return on investment though.
Kohta's BSC presentation examined the question of how "How Low Can You Go" by reframing it by posing "What is the best choice of use of resources on a global scale?" At some point "those last few inches of added insulation levels and low-air sealing rates reach a place of diminishing return and a much longer payback". He asked some great questions such as "... is it helpful to ship super high performing R9-12 windows from Europe with all of the embodied shipping energy when you can install R5-7 windows made in North America?" Is that difference really worth it? Do you really need 16 inch of foam below your floor slab for insulation? Is this too much? Is this affordable and will it pay back over time?
After seeing the PHPP (Passivehause Planning Package) spreadsheets on multiple powerpoint slides, and hearing the passion of those in the audience about the Passivhaus process I had to wonder if all that excruciating detail and input time is worth it and accessible to help mainstream this productive concept? To really drive the software and learn how to design with the system you buy PHPP software for $225 from passivehouse.us then you need to attend one of their 9 day training seminars where you pay $2,100 for full training, nic transporation and lodging, then you sit for a certification exam so when you pass it you can call yourself a certified consultant? Huh? I get tired thinking about this.
This seems rather exclusive don't you think? As an architect and business person who has seen the continued proliferation of new design approaches and standards requiring expensive specialized training, continuing education requirements and project certification costs. I start to see shades of the USGBC which is now a rather large and wonderful non-profit Green Gorilla with its multi-billion dollar sub-industry surrounding it. I like to see this Passivehause become more open source with free ware with free online training you can take via You Tube or other sources. Rather than make it a profit and knowledge center for the few., what if was freely shared and could really impact the many? That's my big idea for this post. Give away Passivehaus to widely disseminate its great system for the greater good. That way, as Bill Reed so eloquently said in his Keynote the day before, the system can "self-evolve".
The aggregate takeaway from all of these sessions is use your common sense and make sure to really start out with as Bill Reed was suggesting the day before, finding the "Vocation for your Project". If going Passivhause helps you achieve your desired "Vocation" then so be it. If you want to build a super-energy efficient home with more window area to frame beautiful views and bring in natural daylight into more spaces you set a more reasonable building enclosure performance standard and invest a little more in heating equipment and possibly additional renewable energy sources to achieve zero energy use. It's all about finding balance and seeding hope for the future through dedicated action today showing what is possible. As Peter Schneider from VEIC a partner on the Habitat House said, "Their goal is to see the Passivehaus applied on a community scale." He also said you can buy a Passive House Modular home design right now from Preferred Building Systems. That's truly remarkable!
Regardless, thanks Efficiency Vermont for bringing together all of these bright and interesting people to inspire those of us who attended to design and build ever better buildings! You helped us learn about the possibilities of Passivehaus to Our House. And you helped us see at the heart of this discussion are moral issues transcending politics and economics. I look forwards to next year.