Most energy/cost efficient way to heat insulated garage workshop
Hello GBA members!
We live in Vermont (zone 6A) and have a 16′ x 24′ single bay converted garage woodworking shop space that’s part of a converted apartment. Originally it was a 2 car, 36′ x 24′ garage, but we converted 20′ x 16′ of the first floor as well as the entire “attic” space into a 2-bedroom ~950 sq ft, 2 floor apartment. The remaining garage bay is insulated but currently unheated. We padded out the walls of the apartment with furring strips to 6″, but left the garage with 4″ walls that are insulated with R-15 rockwool insulation. We are using spray foam and 2″ foam board to insulate the garage door and are planning to put in a plywood floor above the garage floor so that we can insulate above the existing slab floor.
We need to figure out still how best to heat the 16’x20′ converted garage woodworking shop, which has 8’6″ ceiling. We don’t use the workshop enough that it seems to me to make sense to keep it heated 24/7, though we probably use it 3 or 4 days, sometimes more, a week for at least a couple hours, sometimes longer. Perhaps I’m wrong and keeping it heated to 50 when not in use would actually be more efficient, if using something like a small mini-split heat pump. I really only need it to be 60 or 62 when in use, not 70, since I’m usually layered in the winter. Most of the time the outside air temp during Nov-April, when we need heating, is upper 20s, lower 30s, and in Jan/Feb, maybe into the teens and sometimes, but not often, single digits.
The apartment is heated with a fairly efficient combination propane boiler paired with a radiant floor system. One possibility for heating is to add a zone for the garage. We could also add in a propane heater, as there’s already a T in the supply line to the boiler that we could easily connect to.
An ideal system would be the most affordable considering both equipment/installation cost as well as lifetime fuel costs, something that wouldn’t take a long time (10 to 15 minutes max?) to heat up the space if we’re only using it for an hour or two and leaving the heat off the rest of the time, and, if possible, is being run on electric instead of propane, since I’d like to convert the whole property to high efficiency electric heating at some point.
Suggestions? Thanks in advance for your time and expertise!
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