I have a natural gas wall-mounted heater in my lean-to. Started out with propane but a pain to change tanks in the winter. (The tanks were outside of the GH.) It was easy for DH to run natural gas to the little lean-to but I'm sure it would be tough to do in a stand-alone. If you really want to heat during the winter (I do), insulate around the bottom of the walls to help hopefully hold the heating cost down. And yes, supplemental light for sure on dreary winter days.
