Calculate shade depth for passive cooling design
Our window overhang calculator helps design roof overhangs and awnings that shade windows in summer while allowing solar gain in winter. This passive solar design strategy can significantly reduce cooling costs without expensive mechanical systems.
The calculator uses solar geometry based on your latitude to determine sun angles throughout the year. Since the sun is high in summer and low in winter, a properly sized overhang blocks harsh summer sun while allowing warming winter sun to enter. This is especially effective for south-facing windows.
This tool is valuable for homeowners adding awnings or pergolas, builders designing energy-efficient homes, and anyone asking "how wide should my roof overhang be?" or "how do I shade my windows in summer?" Proper overhang sizing is a one-time investment that pays dividends for decades.
Follow these steps to calculate your ideal overhang depth:
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