Solar Subdivision
By Frank O'Brien
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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."
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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
