Drake Landing Solar Community, Okotoks Alberta

Sustainable Home Designs in DLSC Gives Energy Efficient Homes

Nov 16, 2009

BTES, Drake Landing, Okotoks Alberta, DLSC

Drake Landing Solar Community (DLSC) is a unique award-winning example of sustainable home design. Solar thermal energy is stored underground for green home heating.

The Drake Landing Solar Community (DLSC) is a key project in the sustainability vision of the Town of Okotoks, Alberta, about 15 minutes south of Calgary. Year round heating (both space heating and water heating) of the individual single-family homes is handled by a community-wide solar thermal energy system.

Green Housing Designs for Energy Efficiency

The 52-home community is a model of energy conservation planned literally from the ground up, with building started in fall 2005.

The largest subdivision of R-2000 single family homes in Canada
Each house is 30% more efficient than conventionally built homes.
A first in the world, 90% of residential space heating needs met by solar thermal energy.
A reduction of approximately 5 tonnes of greenhouse gas emissions per home per year.

Early reports indicate that "the solar energy system is performing as expected and that the 90% solar fraction will be achieved by year five," according to the DLSC site.

Capturing Solar Energy: How the DLSC Energy-Efficient Home Design Works

"Sunny Alberta" has more sunshine hours than other provinces, making it an excellent site for this system

An array of 798 solar panels mounted on rows of detached garages heat up a glycol-based fluid, collecting about 1.5 mega-watts of thermal power during a typical summer day
An insulated piping system (collector loop) carries the heated glycol to a community facility (Energy Center) where the heat is transferred to water for storage; the glycol flows back to the solar collectors.
During the summer, the heated water is transferred to an underground long-term storage system called the Borehole Thermal Energy Storage (BTES), a set of 144 holes drilled 37 metres deep. In the BTES, which is covered with sand and insulation, pipes containing the hot water transfer energy to surrounding rocks. The cooled water returns to the Energy Center to be reheated. NOTE: It is expected to take five years for the BTES to reach its optimal temperature of 80°C.
In winter, water flowing through the BTES picks up heat, flows back to the Energy Center, and then is circulated to homes (through a district heating loop). In each house, a water-to-air heat exchanger blows heated air to heat the home.
On a sunny winter day, heat from the collectors can be cycled to the houses directly, bypassing the underground storage loop.
If the entire system cannot meet the needs of home heating, a gas boiler in the Energy Center will heat the water going to the houses.

Does the DLSC Green Community Design Meet its Goals?

Green home designs are great in theory. Does this radical "green community" concept work?

The site "went live" in the summer of 2007. According to figures released in the DLSC Newsletter, Issue 1, Summer 2009, the first two years of the project are pretty well on track despite the need for a couple of design corrections and a cooler, shadier first summer.

The solar collectors are 33% to 34% efficient, as predicted.
The system achieved 55% of solar fraction in the first year and 61% in the second year (scheduled for 90% SF by year five as the BTES gradually warms up)
This represents a saving about 73 GJ/year in natural gas usage over a typical (non R-2000) conventional home.
"The Drake Landing Solar Community is the first in the world to achieve this high solar fraction."

The DLSC is an ongoing project due to be completed in 2013. Natural Resources Canada (NRCan) is providing technical support and performance monitoring (the performance of each individual home is measured as well as that of the system). Inspections and upgrades have been made since the community was built in 2007 with the most recent modifications to the Energy Center in spring 2009.

Acknowledgements: Thanks to the Town of Okotoks for DLSC images.