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What is Passive Solar Energy

Passive solar energy is the concept of taking into consideration the effects of natural solar energy during building design to take advantage of daylight, space heating and/or space cooling.  It is called passive solar energy as it does not require special materials, technologies, or systems to convert the solar energy into electricity to then be used for heating, cooling or lighting.   The most common building component used in passive solar energy is windows. Over a year, most windows loose more energy than they gain. Advanced windows can actually be net energy suppliers, with better net annual energy performance than the most tightly insulated wall.For some hints and tips on effective use of energy efficient windows visit the Efficient Windows Collaborative organization.

Passive Solar Cooling   

Passive solar space cooling is used in warm climates around the world.  The key concept of solar cooling is to locate windows in the upper floor of a building so that this space is solar-heated during the warm season.  When the building requires cooling the windows are opened to allow fresh air in and hot air to escape.  By focusing the incoming air on lower levels of the building, or through air ducts in the ground, thus providing further cooling (using geothermal principles) cooler air is brought into the lower levels of the building, and hotter air escapes from the upper level.  Natural convection, or forced air can be used to increase the flow of the cooler air to upper levels of the building.

Passive Solar Daylight   

The basic concept of Passive Solar Daylight is very simple.  If you have sufficient natural light in your home during the day you don’t need to turn on lights, thus reducing the electricity used.Tips on taking advantage of passive solar daylighting can be found at the following link: US DOE Building Technologies Program.

Passive Solar Heating   

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 shade during the hot summer months.

Visit The Canadian Mortgage and Housing Corporation (CMHC) at http://www.cmhc.ca/ to get a design guide on passive solar heating.