I'm trying to size a window air conditioner for a room, but having trouble deciding if the usual guidelines are a good fit.
The room in question is about 230 sq. feet, and does not have full 8 foot ceilings, as part of the room is formed by the gable roof. Based on this I would pick a 6000 BTU unit. However, the room is also roofline with black asphalt shingles, east/west/southern exposure, the long dimension of the space being southern exposure with 2 south-facing skylights. There's no natural shading, and the room is also above an uncooled garage space. I typically see a 10% fudge factor recommended for "sunny rooms", but don't have a clear idea of what constitutes a "sunny room". Would this heat load significantly exceed that factor, and by how much?