Passive Solar Heating

Window shading

One of the main objectives of good passive solar design is to keep the home comfortable during the summer. All those windows located on the south elevation are designed specifically to collect and capture the sun's winter heat and could work to make the house unbearably hot in the summer if not shaded properly.

Two main window-shading concepts can be effectively used in Manitoba.

Within our geographic area, the sun moves across the sky at a low angle in the winter months, closer to the horizon. In summer months it travels at a much higher position in the sky. By designing a soffit roof overhang to a larger dimension than the standard 24" width, the same south facing window can be fully shaded in the summer and yet still allow the sun full access to the glazing and interior spaces in winter months.

In a location such as Winnipeg, with a distance of 14" between the top of window and soffit, an overhang width of 3"-9" is needed to fully shade the window in summer months and still allow the desired passive heat gain in winter months. Because of the difference in the sun's angle, as you go farther north in Manitoba, the overhang needs to get larger to be effective. An R-2000 design analysis can help determine the correct soffit dimensions for your particular house design.

The second popular window shading concept is tree shading. Trees that loose their leaves in the fall can provide shade in the summer and allow solar access to the house in the winter. Proper selection and location of trees is critical. Because of their branches, even some bare of leaf trees block more than 50% of the sun's rays in winter. The tree should be a single trunk tall growing variety, planted close to the house with lower branches removed.

Room orientation

Because some of the rooms within a passive solar home are designed to receive much more daylight and solar energy than others, careful consideration needs to be given to room locations.

Locate areas of higher activity such as kitchens, family, and living rooms on the south.

Dining rooms, bedrooms, and bathrooms should be located on the north side or internally where possible.