Understanding Passive Solar Heating

Passive solar heating uses the sun’s energy collected throughout the day to heat a home. When optimally configured, the system can keep a home warm throughout the night, even in colder climates. Passive solar heating relies on the home’s design features rather than mechanical devices – its orientation, windows and thermal mass – to capture, retain and release heat as needed.

The underlying principle of passive solar heating is thermal mass; strategically placed materials that absorb and radiate heat. Up until recently most homeowners and builders considered passive solar heating unconventional and its components unsightly. Fortunately this way of thinking is changing, especially given the ability to aesthetically blend passive solar components into a home’s skin.

Passive solar heating relies on orientation

A home’s orientation is the key to a passive solar heating system’s success. Orientation must be towards the sun so that the most heat can be collected. Daytime sun enters the home through flat plate solar collectors and/or large banks of windows which – for those living in the northern hemisphere – typically are south-facing.

Thermal mass stores the radiation that has entered through the windows. Brick walls, tile or stone floors, concrete, water tanks and even windows are examples of thermal mass. Thermal mass releases the sun’s heat energy when needed to maintain the desired temperature inside the home. Usually opening windows and doors is all it takes to circulate heated air throughout the home. Sometimes however, fans are set up to assist with circulation.

To reduce heat loss through windows during the night, it’s best to cover them with heavy drapes or shutters. Whatever is installed should completely cover the openings. Adequate insulation in the home’s attic and walls helps reduce heat loss too.

An optimally-configured passive solar heating system takes into account the changing position of the sun during summer and winter months. In the months when the sun is higher, awnings or eaves along a roof block much of the sun and reduce the chance of overheating. During winter months when the sun is at a much lower angle, more sunlight flows through the windows allowing for more solar gain.

Are you considering passive solar heating?

Ideally, the decision to incorporate passive solar heating should be made before construction on a new home begins. Remember, the home’s orientation and the materials used in its construction are crucial to the system’s success. But an existing home can be retrofit with a passive solar heating system, and those with proper solar orientation are excellent candidates.

Aside from the set up costs, once in place a passive solar heating system has very low and sometimes no operating costs. It’s a totally renewable type of heating that doesn’t rely on fossil fuels and doesn’t emit greenhouse gasses during production or use. It’s an environmentally-friendly way to provide heat that’s often referred to as a “clean” source.

More info on Passive Solar Heating
Sound Home Resource Center
WBDG
Do It Yourself Projects

If you’re interested in passive solar heating, be sure to consult with a solar energy specialist who can properly advise you based on the size of your home, its location and your heating needs.