Building balances comfort, impact
Toolbox
Published: February 24, 2008
Five years ago my family and I fulfilled a lifelong dream by designing and building our own house. Much heart and soul went into this project, as well as the thousands of nuts-and-bolts decisions requiring this dream to be balanced against many practical constraints.
Along the way we received a great deal of help, including the truly humbling "framing party" (where over 30 of our friends and neighbors showed up to build most of the frame in two amazing days); the materials bought and donated from the dusty depths of barns and storage sheds; and much advice, information, and insight on building in general and alternative building in particular.
Our very limited budget meant that I would be doing much of the work myself (this had been part of my original dream anyway). It also meant that we would be using alternative, salvaged, and recycled materials where possible, without compromising the quality of the structure. Even more importantly, we wanted both the building process and the eventual operation of the house to be environmentally benign without being too radical. We wanted more than a sod hut without amenities. Instead of radical change we chose a middle path: plenty of space and comfort with a greatly reduced environmental footprint.
In the context of building our new house, what did "environmentally benign" mean to us? Some things were no-brainers. It meant constructing a well-insulated and well-sealed structure, using energy-efficient lighting and appliances, and selecting many natural materials. We also took advantage of passive solar gain (letting the sun in on the south side), landscaping, and natural windbreaks to reduce heating and cooling loads. I evaluated the manufacturing processes for some materials and made my choices based on chemical content and "embedded energy."
Embedded energy is the energy consumed in manufacturing or processing the material. For example, concrete is a relatively benign material, although manufacturing the cement used in the mix is a very energy intensive process. Fiberglass insulation, which retains heat and saves energy, is also energy intensive to manufacture (unlike cellulose insulation, which is essentially shredded newspapers). Vinyl siding is both highly toxic to manufacture and unsustainable in that it is made from petroleum.
The concept of embedded energy of a product can also be represented by "lifecycle costs," in which case the equation also includes the costs and liabilities of final disposal. For example, concrete can be broken up and used as fill or even finely crushed and recycled as material for new concrete mix. Asphalt shingles can be recycled, although they seldom are. Discarded vinyl siding is disposed of in a landfill or is incinerated, which in either case creates a whole new set of problems.
Energy sources should also be evaluated in terms of their lifecycle costs. What are the true relative costs of alternative sources of electricity — wind, nuclear, and coal — not only the cost per watt at the meter, but also the costs of waste disposal and pollution?
We knew from the start that we could not afford a photovoltaic (PV) solar system to generate our own electricity directly from the sun, but we opted to use thermal solar energy as much as possible for space heating and hot water. People often think of solar power in terms of PV systems, but these are more practical in the sunny southwest than here in Vermont. Solar hot water and solar space heating, on the other hand, have a much shorter payback period in this climate. As with any energy-related decisions, efficiency and conservation are always cheaper than new sources of generation.
With these ideas in mind we decided to forgo a conventional furnace altogether and heat with a high mass, radiant, solar slab supplemented with a good quality woodstove. During the day the sun shines into the house and heats the slab, which then releases the stored energy to heat our house during the night. (The story of our solar slab and how it works for us deserves fuller treatment than this space permits and will be featured in a future column.)
So, what did we learn? We learned a lot of do's and don'ts about building. We learned that if we wanted to live free of drafts, we shouldn't buy used windows and doors. We learned that piping makeup air from outside directly to the woodstove can drastically reduce drafts and heat loss. We learned that the pride of living in a self-built house goes a long way toward keeping us warm. We learned that our community plays a valuable role in helping us attain our dreams.
Mostly we learned that there are no perfect answers. There are no perfect building materials, and there is no perfect, endless source of energy. We learned that compromise and balance are the keys to the equation, that energy conservation trumps generation, that we really value hot water and warm floors. We learned that solar heating does work, even though it has its limits and drawbacks like anything else. We learned that we can gladly accept those limits to break free from the oil cycle. As my wife remarks anytime she can, "We will never buy another drop of heating oil!" With current oil prices that's a great bargain.
Robin Chesnut-Tangerman is a green builder specializing in "Renovations and Innovations" and a longtime organizer of SolarFest. He can be reached at tango@vermontel.net.
ON THE NET
Vermont Department of Public Service, Solar Energy Guide:
http://publicservice.vermont.gov/energy-efficiency/ee vtsolarguide.html
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