Which element is used to shade windows in summer while allowing solar gain in winter as part of passive solar design?

• A. Size south-facing overhangs to shade windows in summer and allow solar gain in winter.
• B. Add thermal mass in walls or floors for heat storage.
• C. Use natural ventilation to reduce or eliminate cooling needs.
• D. Use daylight to provide natural lighting.

Answer: (A)

Seasonal shading uses geometry and orientation to control heat from the sun. South-facing overhangs are designed so that in summer the high-angle sun is blocked from directly reaching the windows, reducing cooling needs, while in winter the sun sits lower in the sky and can still enter through the windows, providing solar heat and daylight. This leverages the sun’s changing path across the seasons to naturally balance warmth and cooling.

Thermal mass stores heat to even out temperature swings, natural ventilation reduces cooling needs, and daylighting provides light, but none specifically address blocking summer sun while letting winter sun in through the same windows.