by Rick Reynolds
Q: Rheannon, you were one of 18 young professionals recently chosen by Business Monadnock, the Keene Sentinel, and the Keene Young Professionals Network for their annual “Trendsetters Awards”: the honor awarded to individuals who “contributed to the region’s economy and vitality.” You also just received your Passive House certification. Starting with the “Trendsetters” award; how did this come about?
A: Well, I am a Keene native, graduating in 2011 with a Bachelors degree in Architecture from Keene State College with a special focus on Building Science. I now work as the Energy and Sustainability Specialist for Bensonwood and Unity Homes. But regarding the award itself, it’s fair to say homebuilding and energy efficient homes are vital to the region’s economy. Beyond that, low energy load houses will become more and more important as we attempt to slow or reverse the more damaging effects of climate change. Anyway, Bensonwood Company Steward and Project Management head, Hans Porschitz nominated me and I was lucky enough to be chosen along with an impressive group of young professionals from around the area.
Q: What was the impetus behind making green building and energy analysis your career?
A: I got really interested in the field after the historic market crash and housing downturn after 2009—a trauma the country is just starting to emerge from. Aside from the disastrous plunge in home valuations (and the poor quality of housing stock underlying it), many people at that time couldn’t afford to heat their homes. I wanted to play a meaningful role in lowering the energy needs of buildings—and in a larger sense, becoming a force for change in my industry.
Q: On a related topic, you also recently passed your Passive House certification. Earning Passive House Certification is not an easy thing to achieve. How did you decide to go for Passive House certification on top of your full time job?
A: Passive House certification is the Gold Standard of energy efficiency. In the future, I expect more and more homes to be built to this standard. But in the meantime, the science behind PH designs informs all green building strategies. Originally, my colleague, Hans Porschitz, being German/American, wanted me to go for European Passive House Certification (PHI), a rigorous course even by high European standards. In the end, because of the weather extremes in North America , I decided to go for the North American Passive House Certification (NaCPHC) program issued by the Passive House Institute US, (PHIUS).
Q: There are a dizzying number terms that describe energy efficiency in homes: Net Zero, LEED, Passive House, Energy Star, etc. In simple terms, how is Passive House different from, say Net Zero homes, or LEED for homes?
A: “Net Zero” basically means the home produces as much energy as it consumes. This implies renewable energy generation, like PVs (Photovoltaics) and a highly efficient building envelope; however, regarding the latter, this is not always the case.
Simply put, the LEED standard is a point system that rates the building’s materials (based on their embodied energy), energy efficiency, HVAC systems, Energy Star appliances and fixtures, as well as build site considerations. The point total determines the rating level, Silver, Gold or Platinum, and there are different paths to achieving the same level.
With Passive House certification, the rules are very simple: You’re either meeting their stringent energy expectations or you aren’t. So the Passive House standard is, at the same time, both easy and hard: that is, easy to state, harder to achieve.
Q: Could you explain?
A: Well, Passive House certification is very technical, but the goal is simple to describe: In Passive House, there’s a certain allowance for heating & cooling and a strict energy target: 4.75 KBTU per SF per year (KBTU is 1000 BTU), which is 70% better than what a typical new home built to code achieves and 85% better than homes built before the year 2000. What’s more difficult is reaching that lofty standard.
Q: So, for the layperson, how is that strict energy target achieved?
A: First, a super-insulated, tightly-sealed building envelope is essential. Most people know the importance of insulation, but few appreciate the role air tightness plays. To be specific, an air infiltration rate no greater than 0.60 AC/H (air exchanges per hour) at 50 Pascals is allowed—that’s a very tight building. In addition, high-efficiency, triple-paned windows, properly sited and shaded, play a large role as well. And because the home is so tightly sealed, sophisticated ventilation systems are required to replenish stale air without losing its thermal energy. This is achieved with Heat Recovery Ventilation (HRV) or Energy Recovery Ventilation (ERV) systems where the exhausted air pre-conditions the incoming air with little energy loss. Last but not least, the home must be sited to take advantage the solar, shade, and wind characteristics of the property.
Q: Regarding air tightness, how are Bensonwood and Unity Homes able to achieve Passive House levels?
A: Before I explain that, first off, many Bensonwood and all Unity homes are easily Net-Zero capable even with modest renewable energy generation systems. LEED Platinum and Passive houses, however, are specially designed and configured to earn those designations. But regarding air tightness, all Bensonwood and Unity Homes can achieve Passive House levels of air infiltration, largely because of their montage building methodology, wherein panelized wall, floor, ceiling and roof assemblies are precision fabricated off-site, out of the weather, then rapidly installed on-site. Under shop conditions, window assemblies can be installed into wall panels with greater precision than can be achieved on site. Besides the precision fit, gasket technology and special tapes are used to further seal the building envelope.
Q: What price premium is associated with these low-energy building envelopes?
A: Adding more insulation, while beneficial, does cost more. High efficiency windows cost more, but building tight buildings doesn’t require more stuff, just more skill. It’s not rocket science—it’s just a better building practice. The energy savings over the life of the building, though, will serve as a return on those additional investments—and the reduced environmental impact, internal comfort and exceptional air quality that exists in a home built to the caliber of Passive House will provide long-term health benefits of inestimable value. And therein lies the promise. We need to get the word out, to the industry and the public it serves.