Yes above freezing is very important, and possibly above ~ 45-50 F, as contents could be affected (separation, etc.) by drastic drops. I'd be more worried about what gas fumes would do to my dry goods though.

Ah... Thanks Lucy. I didn't think about that. Maybe just the canned food, then.

You could add more insulation to the room so a small electric heater would keep the temp you want without running all the time. Another consideration is the humidity level. You don't want your dry good to "cake" or the lids on the canned food to rust. But sounds as if this shouldn't be too big a project. Tom

My first thought was adding insulation due to change in temps both winter and summer. An unattended heater would worry me. Although there are heating "mats" for workshops, etc. which could be used. Also heating strips which are safe.

The Greenhouse forum may have some ideas for you. They have many suggestions for managing temp changes and most of their buildings are totally without insulation. There must be some safe and suitable heating options on their forum which might work.