When is it too cold to stay home?

How low can you go?

- lyrics to "Limbo Rock"

I was asked yesterday, "If a house is without heat, at what temperature does it become unsafe to stay?" Or to put it another way, "At what temperature should one evacuate a home?"

I've searched the Internet and found nothing useful so I'm hoping that some reader can provide an answer. One site said that temperatures below 70 F can be dangerous (to the elderly perhaps???) if no protection is taken (like a sweater?). That seems way too extreme. At my home in winter, I'm lucky if I can convince the wife to set the thermostat up to 63 F. It's often 60 by day and 55 at night. For me 63 F is tolerable with layered clothing but below that my fingers become chilled.

When we lost power with the Halloween Nor'Easter we put on coats and hats and did OK for awhile as the temperature fell over several days. At 40 F we were becoming concerned but then the power was restored.

A site on wind chill said that -20 F was "dangerous". It may be true that even brief exposure to -20 F is dangerous but what about prolonged exposure? Someplace else warned about 30 F and below.  At that temperature you must to take active precautions to prevent your extremities from freezing with frostbite but it is survivable. When I attended an igloo making class the instructor warned against overheating the inside of the igloo. If the temperature got above 32 F the igloo would melt from the inside-out. So igloo dwellers must cope with the 30-32 F range.

Bottom Line

There might not be one simple answer. Temperature tolerance does depend on age and health and body fat. Still it would be nice to know how low is safe?