Letter Re: Survival Architecture: Building a Retreat that is Defensible, Sustainable and Affordable
James Wesley: On March 25, we saw a post by Phil M. indicating that “At a point of 6′ below the surface of the earth, temperatures stays constant at around 60°F.” This may only be true for very specific locales. For most locations, constant ground temperature reflects the average yearly air temperature for the locale, and ground temps are only constant at a depth of about 30 ft. and below. At depths above 30 ft., ground temperatures begin to increasingly modulate up and down following seasonal air temperature. In areas of the world with seasonal temperature changes similar to the …