Going for the Sun: Solar-based Communities Break Ground
By Yvonne Jeffery, Calgary Herald – December 3, 2005
With high oil prices continuing to put the squeeze on household heating budgets, our occasional series looks at a variety of alternative energy sources for our homes – from solar energy to wind power. Today, we take a look at solar-heated communities.
Imagine a neighbourhood of 52 R-2000 single-family homes, basking in Prairie sunlight that provides up to 90 per cent of each home's space heating requirements. It's not science fiction: construction is already underway at the Drake Landing Solar Community in Okotoks.
"It's the first of its kind in North America," says project leader Doug McClenahan at Natural Resources Canada, which is working on Drake Landing with the town, developer United Communities, homebuilder Sterling Homes and more than a dozen partners.
Clean, dry air and plentiful sunlight make southern Alberta and Saskatchewan ideal locations for solar heating applications, says University of Calgary architecture professor Tang Lee, who's currently working on a proposal with Calgary's MV Pedersen Engineering to solar-heat the entire town of Vulcan. "We have one of the best places in Canada for the intensity of solar radiation," he explains.
To understand how solar-heated communities work, Lee suggests replacing the concept of each building having its own furnace with that of "district" heating. "We want all of the buildings in the town tied into one furnace," he explains.
That furnace, or power plant, produces heat in the form of hot water, which then travels through insulated pipes throughout the community. A power plant could be a huge gas boiler – but for solar communities, it's a field of solar collectors that gather heat from the sun.
Of course, in winter – when we need heat the most – we have the least amount of sunlight available. "With any type of solar system, the heat demand is opposite the amount of solar availability," Lee explains. This means that thermal storage becomes the key to a solar heating system: heat generated by the collectors in the summer must be transferred – usually to the ground or to water tanks – until it's needed.
In Okotoks, approximately 800 solar collectors, or panels, will be mounted on garage and breezeway roofs. The heat they collect will be transferred in antifreeze-protected pipes to an Energy Centre, where – if the heat isn't immediately needed – it will be transferred into water-filled pipes feeding into a "field" of 144 boreholes drilled 37 metres into the ground. The earth will absorb the water's heat, warming to 80 Celsius by the end of each summer season.
When the heating season arrives, the pipes will reverse the process: heat from the ground will transfer into the water in the pipes. Those pipes then hook into a loop that feeds each house. In the house, an air handler transfers the water's heat to the air, distributing it through forced-air ductwork.
In Vulcan, centrally solar-heated water would supply both space heating and domestic hot water for the population of approximately 1,800. "The beauty of this is that (the individual) buildings no longer need a furnace or a hot-water heater," says Lee. That saves space within the home, reduces maintenance requirements, and reduces risks such as carbon monoxide poisoning.
In Okotoks, each house will also feature a stand-alone solar-heated hot water unit that will supply up to 60 per cent of the home's hot water, backed up by a high-efficiency natural gas heater. The combination of solar space and water heating is expected to reduce annual greenhouse gas emissions there by five tonnes per home.
At both projects, homeowners receive the benefits of alternative energy sources without the hassle of having to maintain the systems required. The question most often asked is whether the solar systems can handle the heating needs.
McClenahan explains Drake Landing's energy centre takes care of that. "It's backed up with two natural gas boilers," he says.
Vulcan will have similar failsafes, notes Lee. "There's always a backup. It's crucial that we have no failure – the solar is not the only heat source. We're also looking at burning straw and even natural gas as a backup."
At Drake Landing, homeowners will pay a fixed monthly fee for the heating system, just as they'd pay any other utility bill.
Tyler Stevenson, project manger for United Communities, Drake Landing's developer, says the company came onboard partly because they wanted to assist homeowners to reduce or level out rising heating costs. When the project was established, they calculated a conventional home in Okotoks was averaging $60 per month for heating – so they used that as a benchmark for their "utility" fee. With gas costs rising sharply, Drake Landing homeowners should see a benefit to their fixed utility fee almost immediately.
The Vulcan project will operate similarly, with a total project cost of $15 to $20 million.
"The beauty of this is the economy of scale – it makes it more economical than a solar array for each individual house," says Lee. Besides, he adds, the use of fossil fuels has environmental damage costs, along with quality of life and health issues that aren't calculated in the payback factor. "What we're paying for fossil fuels is not the real cost," he says.
Seven showhomes are open in Drake Landing and the solar heating system is currently being brought online. Phase 1 of the 52 Built Green-certified homes – ranging between 1,490 and 1,660 square feet – has already sold out. "By this time next year, all the homes should be constructed and all the solar panels built," says Stevenson.
As for Vulcan, Lee says they're finishing the pre-engineering study. "It's not the final design, but there's enough information for a very good cost estimate for the project." That means the project's feasibility – including how long would it take, compared to fossil fuels, to pay back its investment – can be assessed.
"The most important thing about (the Okotoks) project is that it will be an example of a subdivision of the future," says McClenahan. "This will be an example of what you can do in the future with a local renewable energy source – it does not depend on bringing in outside energy sources like fossil fuels."