Passive solar heating is the use of the sun to heat buildings. Careful design and positioning of a building can ensure that sunlight in the winter months will warm the interior by day, with much of the warmth remaining during the night. Summer sunlight is usually kept out.

 

Advanced windows have improved the outlook for passive solar space heating. It can be as simple as choosing windows for your building with a higher or even positive energy rating. For more energy savings, or better passive solar utilization, one must also choose other components and/or design the building appropriately. These additional components include a large interior thermal mass (e.g. concrete) to hold heat and a well-insulated building envelope. The windows should be predominantly on the south side and as few windows as possible on the east and west sides of a building to prevent overheating. Roof overhangs can also be used to provide shading of the windows during the hot summer months.