What is passive solar design?
Passive solar design is taking advantage of the sun and other site conditions to maintain a comfortable living space without the use of mechanical equipment. This takes place in the planning stages of a building design and is carried through with the right use of materials. Ideally a house in San Diego County can be designed to not rely much on energy (electrical or gas) to maintain a comfortable interior temperature. Active solar designs (photovoltaic solar panels and solar water heating systems) are also useful but a separate subject matter.
How to Plan for Passive Solar Design
- MAXIMIZE WINDOW SPACE THAT FACES SOUTH. The reason you want more exposure to the south is because during the winter (when you want your home heated) the sun is primarily to the south.
- MINIMIZE WINDOW SPACE THAT FACES WEST & EAST. The reason you want less exposure to the east, and especially the west, is because in the summer (when you don’t want your home heated) the sun is to the east in the morning, almost overhead during midday, and to the west in the afternoon.
- PROVIDE SOME HIGH WINDOWS THAT FACE NORTH. Small north facing windows located high up on the walls are good for providing natural lighting to a building while minimizing heat gain.
- PROVIDE OVERHEAD SHADING FOR SOUTH FACING WINDOWS. This will block the high summer sun from overheating your home while allowing in the lower winter sun. An ideal sized shading structure can be designed based on the size, location, and orientation of a window.
- PROVIDE VERTICAL SHADING FOR WEST AND EAST FACING WINDOWS. This will block the early morning and late afternoon sun in the summer while allowing in light year long. An ideal sized shading structure can be designed based on the size, location, and orientation of a window.
- THERMAL MASS. In a mild to moderate climate the ideal thermal massing of a building is one that is elongated along its east-west axis. The goal is to maximize exposure to the south and reduce exposure to the east and west. Another thermal strategy is to use walls made with thick dense materials such as adobe, concrete, block, or rammed earth. These “thermal mass walls” slow the transfer of heat into the building, keeping it cooler in the day and warmer at night. Solid exposed floors, such as concrete or tile, near south facing windows work similarly to absorb heat in the day and slowly release the heat at night.
- STACK VENTILATION. Since warmer air rises, planning operable windows located towards the highest point in a room or building makes an ideal place to vent warm air from a building.
- CROSS VENTILATION. The quickest way to feel cool during warm conditions is to provide air movement in a building. By planning operable windows on opposite sides of a room or building, breezes can pass through living spaces and make them more comfortable.
- SITE CONDITIONS. There are many other thermal strategies that can harness natural processes to maintain a comfortable building. A good understanding of a site can gain insight into what direction cool breezes come from, what areas heat up more, and what times of the year heating or cooling are desired.