A 10x10 room in a moderate winter zone needs 22btu/sqft or 2200btu which is about 650w. With a 900w heater, what is the maximum temp I could maintain with an outside temp of -5C/23F? Moderate winter zone is defined as a minimum 0C/32F.
Here are the room's construction details:
There is a 5' vinyl double glazed patio door (unknown R value). The room is facing west with another exposed wall facing south above an enclosed garage (not sure if the garage ceiling is insulated). 8' ceiling with R20 insulation under a pitched roof. Wind is not an issue here, about 150kms north of Seattle. Exterior walls are 2x4 so probably R12 insulation.