We are currently renting a home from some (wonderful) neighbours. It's an older home, a townhouse. And they've done many things to improve it over the years. However, Mark's been noting the depressing frequency with which our furnace turns on. His last count clocked it at 8 minutes. Which is to say that in 8 minutes, our house is losing one degree of heat to the great outdoors. If the furnace conked out and we lost a heat source, for whatever reason, our house would reach the outdoor temp, let's say a balmy -8° C for this scenario, in just under 4 hours. Half way through sleep. A couple hours and it's inhabitable. I find this shocking.