Valid question, I don't know the exact answer, but keep in mind that a closed cabin with windows will heat up naturally when the sun is up. Humans generate heat

Valid question, I don't know the exact answer, but keep in mind that a closed cabin with windows will heat up naturally when the sun is up. Humans generate heat which is also trapped in that cabin. Inefficiencies in transmission etc... also generate heat although I'm not sure it's enough to make a difference. Remember that the international space station is artificially cooled despite one side being exposed to 0 Kelvin.