The Greenwich Citizens Committee, Inc and Battenkill Transition Communities sponsored Transition Town trainer Tina Clarke last night at the Greenwich High School library. In spite of dreary weather, approximately 60 area residents showed up to hear what Tina had to say about her “Zero Energy Power-House” otherwise known, by Carl McDaniel, as a net positive energy home.
Tina opened the session with an unexpected bonus, an introduction to Transition Towns. She described their origins in England and their approach to working with local communities to facilitate the move from oil dependency to local resilience. She said while the founders did not expect to create an organization, there are now over 100 Transition Initiatives in the U.S. and several thousand around the world. She recommended Rob Hopkins’ “The Transition Handbook,” of which we (www.OEIC.us) will provide a review of in the near future, and also the “Transition Companion,” a more recent book that is now available.
Next she got into what most had come for, a discussion of her award-winning “Zero Energy Power-Home.” This home received a -8 HERS rating, indicating less than zero energy used. She stated that the house actually produced 2.5 times the energy used in its first year of operation, 2009. This is a simple, one-story home – slab on grade with 6” blue board insulation under the slab, overall it is 24’ x 48’ (1152 square feet) with the long side oriented towards the south to maximize local solar gain. The 4” slab was finished as the first floor to capture solar heat by day and warm the space at night.
A great deal of effort but only a modest amount of money were invested in building an extremely well-insulated and air-tight building envelope. The walls are 12” thick with dense-packed cellulose (R-42) and the roof was built 18” higher at the exterior walls to allow for a lot of cellulose (R-103)! The windows are triple-pane, argon filled windows. The south-facing windows have a higher solar heat gain coefficient to admit more sun than windows on the east, west and north sides of the house. [Editors note: There are limited window manufacturers that provide real choices of thermal/solar performance levels appropriate for different orientations within the same style. Serious Windows, a U.S. company, and two Canadian companies Accurate Dorwin and Thermotech are familiar to me.]
As with any well-insulated house, mechanical ventilation is required; a heat recovery ventilation system was installed that warms the incoming fresh air and saves energy. The overall result of the high performing shell is a home that can be heated with a small air-source heat pump. Ms. Clarke noted the low cost and high efficiency of the air-source heat pump, which she powers from the photovoltaic electricity panels on her roof.
Another area where Ms. Clarke spent money was on sustainable wood and non-toxic finishes. Among other items, she obtained beautiful used interior doors and trim from, Renew, a building materials recycling organization in Brattleboro, Vermont. Paints were all environmentally friendly, with one, she joked, almost as edible as salad dressing. [Editor’s note: please don’t eat paint, any paint.]
Cost of the home was approximately $180,000 or about $156 per square foot – a price competitive with “fancy” code built homes in our region with ornate heating bills for life! That price included solar panels, extremely high-efficiency appliances, and “healthy home” finishing. You can see additional details about the house here. Information about the global Transition movement is here. And more information about Tina Clarke’s work to help communities transition from oil dependency here.
The evening wound up with questions mostly about how existing homes can be improved. Tina provided some details and slides. She said that quite a lot can be done with existing homes, including deep energy retrofits. The “gold standard” in home energy efficiency is now “Passive House.” To bring an existing home up to Passive House standards is very expensive – potentially $120,000 to $200,000. She promised to have the existing home slides on her website by the weekend after Thanksgiving.
Dan Gibson is the Reporter and Chief Coordinator of Our Energy Independence Community (www.OEIC.us). Previously he performed home energy audits for five years in NYSERDA’s Home Performance program and new home ratings in the New York ENERGY STAR Home program. He is currently building a 100% Solar Home. He can be reached at DanG@OEIC.us