by Frank Tettemer and Cheryl Keetch
Our house is 1700 sq. ft., two story, with the lower story earth sheltered on three sides with the south side exposed as a walk out. Roof and first floor overhang designs allow for shade in the summer and passive solar gain in the winter. The primary heat source, for space heating and domestic hot water, is an airtight wood stove, also used for most cooking and baking tasks for half the year. Back-up heat is radiant floor in the downstairs, fired by propane.
During the summer, domestic hot water is obtained through the use of flat plate solar collectors. This solar supply is useful only when the sunny days outnumber the grey days, as storage is only forty gallons. Thus, some propane is used to supplement during extended cloudy periods. Propane is also used for summer cooking.
The remainder of the home operates on an average of 2 kWh per day, for lighting, water pumping, refrigeration, kitchen appliances, laundry, and entertainment. This electricity is supplied by 26 photovoltaic panels and a small Whisper 1000 wind generator. During extended cloudy periods, (such as this winter!), a gasoline fired generator is run occasionally to charge the bank.
Our house used a total of 700 litres of liquid propane, for supplemental heating in winter, cooking and back-up domestic hot water in summer. The total electrical use for the year was 802 kWh for the previously above mentioned electrical appliances. This electrical energy came from solar and wind sources, plus the use of approximately 100 litres of gasoline for back-up generation. Generally speaking though, this house is not completely 100 percent sustainable, as it does consume some fossil fuels.
A Client's Home
Our client Skye Faris' home, is much closer to being fully sustainable. It is a two story, 1050sq.ft. straw bale home, with much passive solar gain, adequate thermal mass storage, and a solar off-grid electrical system. It was built with a Sunmar composting toilet, and a class II greywater system. Domestic hot water is fully supplied by wood heat in three seasons, and solar water heat in the summer. Cooking is on a wood stove three seasons, and propane during summer. Skye has created her own thermal curtains which she uses to conserve heat loss, when ever there is no solar gain. Thus, she uses less than six face cords of fire wood per year. She also has stated that she goes for two years on a single tank of propane, (equal to 90 litres of liquid propane).
Her entire supplemental energy consumption amounts to six cords of wood and half a one-hundred-pound-cylinder (45 litres) of propane for the year! I would like to offer this home as a prime example of sustainability; something to use as a goal.