How much glass a facade should have
Facade area, glazed area and the floor behind it. Get the window to wall ratio, a reading of it, and a daylight rule of thumb.
Glass, daylight and energy
The window to wall ratio is the share of a facade that is glass. Around 30 to 40 percent balances daylight against heat gain and loss in most climates; above 60 percent the facade needs serious shading and a good glass specification.
Daylight depends more on the floor behind the window than on the facade. Glazing at a tenth to a fifth of the floor area lights a room of normal depth; deep rooms need more, or light from a second side.
Energy codes put limits on glazing by orientation and climate. Use the ratio to shape the facade, then check it against the code and a daylight study.
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The numbers are done. Now the image.
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