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Solar Subdivision
By Frank O'Brien








What started as a bonus zoning opportunity and national research study is building into the most advanced energy-efficient and water-saving new home subdivision in Canada.
For developer Tyler Stevenson of United Communities, the deal from the town of Okotoks was promising. For every 20 per cent in water savings for each house built on acreage he owned, United would be allowed a 10 per cent higher density. For United, that meant about 85 new houses more for its giant Drake Landing subdivision in one of the fastest-growing municipalities in Canada, just 18 km south of Calgary. The population of Okotoks has increased 37 per cent in the past five years, putting pressure on its water supply.
Sheep Creek winds through Okotoks, and the small river determines how many people live there. The Sheep can deliver water and carry away treated sewage for a community of 30,000 at most. The town's population is cresting over 12,000, so Okotoks is already near its half-way mark.
Drake Landing, therefore, was seen as a pilot case of how to save water. And in Alberta, where the Built Green program was founded two years ago, it was natural that R-2000-level energy savings and environmental awareness would be part of the plan.
With seed funding from the Federation of Canadian Municipalities and financing and expertise from Natural Resources Canada, the first phase of Drake Landing, 52 detached houses, is now being built into the largest solar-powered residential project in the country.
Sterling Homes, a subsidiary of Sterling Group of Calgary, is using a large-scale and innovative solar heating system to supply more than 90 per cent of the heating for the new houses, all of which will be rated as R-2000 and as Gold under the Built Green program. As well, using special water-saving appliances and fixtures, each of the houses will use at least 20 per cent less water than a conventional house.

Ground heating loop
The solar homes will be heated by hot water from a unique heating loop. As well, an independent two-panel solar thermal system will provide 60 per cent of the homes' domestic hot water needs.
All the houses are outfitted with numerous energy-efficient innovations, including low-flow plumbing fixtures, EnergyStar appliances and low-impact landscaping.
Approximately 800 solar collectors will be mounted on roofs of interconnected garages and breezeways, generating up to 1.5 MW of thermal power. In the summer, solar energy is collected and stored in a "borehole field" under the neighbourhood park. In the winter, heat is extracted from the field and delivered to the homes as hot water through underground, insulated pipes. On sunny days, solar energy is collected and stored in the field.
Each house will have an "air handler" instead of a furnace. The home's air is heated from the water and distributed throughout the home using conventional forced-air ducts. The homeowners will set their thermostats for individual comfort, just like other homes.

Borehole system

The Okotoks borehole storage field is an array of 144 holes, each 115 feet deep, that cover nearly half the size of a football field. After drilling, a plastic pipe with a sealed "U" bend at the bottom is inserted down each borehole. The borehole is then filled with a grouting material with a high thermal conductivity.
At the surface, all of the U-pipes are connected together, and then linked back to an Energy Centre building. The borehole field will be covered in a layer of insulation and then soil, with the park built on top.
The operation is fairly simple: when solar heated water is available, it is pumped into the centre of the borehole field, through the U-pipes, transferring the heat to the soil and rock, and gradually cooling as it reaches the outer edge of the field.
Conversely, when the homes require heat, cooler water is pumped into the edges of the field, flowing to the centre as it picks up heat. The heated water is then circulated to the homes through the district distribution loop.
ATCO Gas, Alberta's largest natural gas distribution company, will manage construction as well as operate and maintain the heating system during a commissioning period, after which it will take ownership of the system.
It will take about three years to fully charge the bore field, according to Keith Paget, Sterling's project manager. However, the core temperature of the field could eventually approach 80°C by the end of summer, with sufficient heat for almost an entire heating season, he explained.
"We have five basements dug so far with two more to go within the next week," Paget said in mid-April. "We are building a sales centre, using the main floor of a house, four furnished show homes and two unfurnished show homes. There are six unique models for the project, each with four choices of elevations."

The solar home project has a number of financial sponsors, including the Federation of Canadian Municipalities and Natural Resources Canada.
By using solar energy, the Okotoks project is estimated to reduce green house gas emissions for each house by five tonnes per year. That translates into 260 tonnes per year for the entire subdivision.
The homeowners will be charged a favourable long-term fixed monthly fee. Although the system's costs will not be competitive with today's price for fossil fuels such as natural gas, the scale of the demonstration will be large enough to make it competitive with higher-priced conventional heating sources such as electricity. The operating costs will be lower than those of a combustion furnace. In addition, the project will provide invaluable information for future, larger-scale projects.

Opens in July
The first of the solar homes are expected to be completed by this July, according to United's Stevenson. Also expected is a fast sellout of the houses, priced at an average of $220,000.
While the marketing doesn't kick in until the opening of the showhomes, Sterling general manager Bill Bobyk notes that twice as many people have already registered for information than the number of houses Sterling is building. "We are getting calls from as far away as Vancouver," he said, noting the project has sparked a buzz in the media and the home building industry.
Bobyk, chair of the Technical Committee of the Calgary and District Home Builders' Association, said the innovative Okotoks project shows "what can be done when you have cooperation between the building industry and all levels of government. It is an excellent example of how houses could be built in the future." HB

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