I've read that on Mars you lose 30% of your heat through convection and 70% through black body radiation. (The much lower amount from convection due to the tenous atmosphere vs. Earth.) http://www.sciencemag.org/news/2014/06/no-wind-chill-mars
If so could the heat be used in greenhouses attached to the base? It seems wasteful to not use it elsewhere. The greenhouses would have a higher pressure than the atmosphere which should also increase convection from the radiators of the habitat.
One final question, what pressure would be high enough on Mars that you would not need to heat or cool? I understand Mars is too low in pressure, as is obviously the ISS or the moon, and Earth pressure is too much so that you quickly become cold due to convection. 30,000 feet also appears to have too much pressure and cause excessive cooling due to convection. The paper below appears to be a study of altitude, pressure and convection rates in avionic equipment but the data is not easily extracted.