I won't claim that we have, but I'd point you to a project that's in Alberta. It's owned by ATCO Gas, and it's in the town of Okotoks, just south of Calgary. It's a fully residential subdivision with single-family detached homes. It has a combination of geothermal and solar thermal heating systems backed by natural gas that have been operating for a couple of years. It's a stand-alone community, and it's all single- family residential housing. So it can work.
On March 5th, 2009. See this statement in context.