maybe Molasar is referring to ye olde outhouses?
Up here we'd never leave the house unheated because we wouldn't leave it for more than a couple of weeks tops, but maybe people with cabins would? I dunno. We'd just turn the thermostat down to sufficiently above freezing (exact temp depends on what animals remain in the house) Like twinkie says, all pipes are away from the exterior walls except the ones to the outdoor faucets and we winterize those in November.