Planned Community Stores Heat Underground
by Jacob Gordon, Nashville, TN on 01. 5.06
It just makes sense, doesn’t it? It’s hot in the summer, it’s cold in the winter. So why can’t we just save that hotness until we’re freezing in the wintertime and we want to be warm? If a kid said it we’d laugh. But when a master-planned solar neighborhood springs up based on the idea, we’re going to have to apologize to that brilliant kid. The Drake Landing development in Okotoks, Alberta, is 52 family homes connected to a solar heat storage system that does just that--it stores the summer heat underground. It is the first of its kind and residents move in next month.
Here’s how it works. Solar collectors on the houses’ garage roofs heat glycol that is pumped in a circuit underground to a heat exchanger at the Energy Center housed in its own little building. The hot glycol heats water. The hot water is then injected down into the ground, into a network of boreholes that go as deep as 37 meters down. The hot water heats the earth and the earth holds the heat. In the winter, this thermal mass will take care of 90% of the space heating and water heating needs for the 52 homes in the community (there’s a great animation of how this works on the website). Considering that winter temperatures in Alberta are more than 20 below, this is a pretty serious challenge, and it will take two years for the borehole system to store enough heat to cover the projected heating load.
This is another wonderful example of apparently simple ideas being refined into advanced systems. It’s all coming together, people! :: Drake Landing via Environmental Building News
Better hope that the glycol pipes don't leak in 30 years. On that risk alone, this could have permitting difficulty if a manufacturing industry in the US proposed it. For a residential use I would expect a similar level of concern. Think of it as a series of very long underground storage tanks that would be impossible to remove once installed?
This one innovation has hit three of Socolow's climate stabilization wedges, efficiency, reduced energy, and reduced carbon emissions. It has a lot going for a bit a few downsides as well, mainly needing new exurban suburbs to be built in. I've posted my thoughts at Earth Sentinel - my site about peak oil, renewable energy, and climate change.
I liked this concept back when it was called living in a big stone house i.e. the stone walls retain heat from the summer and release it till most way though the winter and vice versa.
Is someone under the impression that "glycol*" is radioactive or some other ridiculous thing? I do not understand what is the huge risk of pipes leaking glycol from a danger perspective.
*(i assume that this is short for ethylene glycol as opposed to propene glycol)
I'm actually using this system for four new townhouses currently being built in Halifax, Nova Scotia, Canada right in the middle of the city. No suburb, just sustainable urban green housing. Our system is smaller version of the Drake subdivision and we might have extra heat left over to feed into already existing nearby neighborhood houses and businesses. And the closed-loop boreholes aren't fed glycol through tubes but a high pressure grout sealed borehole well wall. No leaks there. The thing about sustainable building, I think, is stopping suburb dev and maximizing urban infill. Only problem, not a lot of passive solar sites in infill urban so how else can one take advantage of solar and waste building heat? Forget the unsustainable suburbs, this system shines in the urban context. The guys who designed the big system in Alberta have designed my system and we est that we'll save between 70-80% GHG emmisions and energy costs using building waste and and solar hot water panels. This system is a non-brainer for both new urban buildings and existing ones using already using hotwater heat rads. Simply, a no brainer.