calculating BTU needed
I have a single story room addition, 16X25, which is built on piers, floor insulated. It will be a four season patio room, so there are two 6' sliders and outside wall basically all windows. About 180 sf of glass on the three walls (all Low E). I was wondering about heating it with electric baseboard on the outside (east facing) wall (which is 25'). I am in Massachusetts, and not sure what size (BTU) I would need and if electric may be too expensive. Was going to install a direct-vent gas fireplace as heat source, but maybe would like to try something cheaper if I could.