Passive Solar Heating

Passive Solar Heating

Passive solar is the most cost effective approach to maximizing the use of solar energy for Canadian homes. Passive solar heating of buildings occurs when sunlight passes through a window. The term passive suggests that no additional mechanical equipment is used other than normal building elements. All passive solar applications use building elements such as walls, windows, floor and roof in addition to exterior building elements. Landscaping can be used to control overheating by proving summer shade. Landscaping can also provide windbreaks for winter winds, and surfaces that can create sun pockets and reflect and reflective surfaces for winter sun.

Once the heat is collected inside, a well-insulated airtight building envelope helps prevent heat loss and allows the sun to provide more of the heat needed by the house.

At Canadian latitudes, proper design of exterior overhangs and shading devices can be optimized to get maximum sun penetration in winter, when it is needed most, and shade for most of the walls during the summer, when it is least wanted.

When retrofitting an existing home, some significant changes to window areas may be desired. Building code regulations for fire safety may restrict the amount of south side windows that can be used if the south side is near a property line.

Solariums are one of the most common and effective approaches to gaining solar energy in an existing home. They can be an attached solarium, or integrated into the existing structure. To reduce temperature swings, and uncomfortable overheating, the solarium should include reasonable thermal mass to store heat. This can be an insulated concrete floor slab with an exposed concrete or tile finish, a masonry feature wall, and even double thickness drywall. Water tanks are an excellent heat storage medium, and they can sometimes be incorporated into the design.

To be effective as a solar collector, the solarium should be treated as an area that can be closed off from the main living area at night. Even high performance insulating glass has heat loss, so the large solarium glass area can lead to an uncomfortably cool space on a cold night.