Off-Grid in a Cold City: The Alberta Sustainable Home

Ted Rieger is a Sacramento-based freelance writer who specializes in energy issues. Jeanne Byrne is Home Energy's managing editor.

The Alberta Sustainable Home is a new suburban three-bedroom house and office that will soon be independent of the sewer, electric, and water systems. Located in the cold, dry, sunny climate of Calgary, AB, the home is now demonstrating the feasibility of environmentally sustainable, cost-saving devices-from Eco-studs in the framework to graywater heat recovery devices.

Although it was built for about the same price as a comparable conventional home, the Alberta Sustainable Home has received a preferential mortgage rate, is expected to have an unusually high resale value, and will cost about $1,500 per year (Canadian) less for utilities.

The Alberta Sustainable Home was built privately by Autonomous and Sustainable Housing Incorporated (ASH), in partnership with some 215 companies worldwide. Construction began in September 1993, and the designers and builders have lived and worked in the building since April 1994. About 13,000 visitors have toured the home to date.
 
 

Design strategies and technologies to reduce energy needs include high R-value insulation, heat exchangers, high-performance windows, energy-efficient appliances, airtightness, water conservation technologies, and passive and active solar systems. The designers are also testing other renewable-energy technologies, and have tried to minimize indoor air pollution. They used renewable resources, salvaged items, and materials with low embodied energy wherever possible.

Solar power is the house's primary energy source. Active and passive solar designs take advantage of the fact that Calgary has the highest number of bright sunshine hours of any major Canadian city. The home's acrylic stucco exterior helps absorb and store passive solar heat. For instance on a cold day the temperature of the stucco may be -13C (9F) in the shade and 21C (72F) in the sun. The lowered temperature difference across the wall decreases conductive heat loss. Dark interior floor tiles and heavy brick in the fireplace provide thermal mass. A modest array of grid-connected photovoltaic (PV) solar modules is expected to produce about 2,000 kilowatt-hours (kWh) per year. Passive solar devices provide hot water and space heating, and residents use solar box cookers.
 
 

The domestic water heater consists of a horizontal 80-gallon tank containing three heat exchanger coils. The first brings heat from the fireplace; the second brings heat from a solar panel on the roof; and the third provides hot water for a radiant floor heating system.

A ground source heat pump is also being installed that is expected to have a Coefficient of Performance (COP) of 5.5. The piping was buried under the water storage cistern 10 ft below grade, where the yearly average temperature is 5C (41F).
 
 

Conventional heat recovery ventilators (HRVs) are supplemented by heat exchangers on the dryer exhaust and the graywater outlet. The ventilation air is also preheated by the dark stucco of the south elevation and a solar hood collector that collects the warmest outside air off the south wall. Within the house, heat is destratified with a fan that blows warm air from the second floor through tubes into the concrete slab for storage.

A seven-filter Nutech scrubber air cleaner was also installed for dust, smoke, and pollen control between the HRV and the fresh-air diffusers to the house.

The Alberta Sustainable Home's shallow foundation saved substantially on building costs. Instead of a typical concrete foundation and footing, the house has a 2-ft deep trench around its perimeter, which is filled with gravel. The foundation is insulated under the slab with rigid foam (Terra Foam); the insulation also extends four feet horizontally from the edge to intercept the heat from the slab and stop frost penetration.

Using both technology and tradition to keep food cool, the house's ultraefficient Vestfrost refrigerator/freezer (left) is next to a cold closet vented to the outside that keeps less perishable foods in the summer and allows the occupants to unplug the refrigerator in the winter.

The home has a rainwater collection system that channels water from the roof, which was treated with an elastomeric polymer so that the water would not pick up pollutants from the asphalt shingles. Sewage treatment will eventually be handled completely on-site, with graywater applied to the landscape. Once all treatment facilities are operational in spring 1996, the residents will disconnect the home from city water and sewer lines.
 
 

Many parts of the house were made from recycled materials. For instance, the dark floor tiles in the living room, dining room, greenhouse, and kitchen are made out of waste material from the manufacture of fluorescent light bulbs, while the lighter floor tiles in the office and the kitchen counter contain 73% recycled glass from such sources as car windshields. Rebars used in the slab-on-grade for crack control are made out of old steel from junked cars; the metal webbing and nailer plates in the roof rafters, floor joists, and Eco-Studs are 60%-70% recycled metal; the weeping tiles in the rubble trench and the radiant floor air pipes contain 40% recycled polyethylene; and the Louisiana Pacific Fiberbond exterior wall sheathing contains 23% recycled newspaper.
 

A good technology for lighting retrofits is the Sunpipe, which is less expensive than installing a skylight into an existing house. The designers installed a Sunpipe to provide sunlight for the hallway, bathroom, and north bedrooms. It channels light into the house with a minimum of glass area for heat loss. The Sunpipe has worked well, although the occupants have noticed some condensation because it is not insulated well enough.
 

The Alberta Sustainable House was designed and built by Jorg Ostrowski, Helen Ostrowski, Orian Low, and Karen Braun of ASH-Autonomous and Sustainable Housing Incorporated. For more information, contact them at 9211 Scurfield Dr., NW, Calgary, Alberta, Canada T3L 1V9. Tel: (403)239-1882; Fax:(403)547-2671; e-mail: ash@freenet.calgary.ab.ca
 
 

Home Energy can be reached at: contact@homeenergy.org
Home Energy magazine -- Please read our Copyright Notice