Passive solar design dates back over 2 and a half millennia to the ancient Greeks and Chinese; it not only predates modern HVAC systems, but also modern materials. So it makes sense that earth-built homes would play well with passive solar techniques.

In this video, natural building expert Michael G. Smith of the Emerald Earth Sanctuary shows us how they use straw bale to insulate northern walls and cob as a thermal mass on southern surfaces and an earthen floor as a heat sink.