Green Buildings: Passive Solar Design

Barbara McClintock, C.Tr.
(Language Update, Volume 3, Number 4, 2006, page 22)

Basically, passive solar design is about keeping summer sun out and letting winter sun in.

Passive solar heating (chauffage passif) requires the application of the following passive design principles:

• Southeast orientation for the majority of the glazing (vitrage) (Your house plants will love this orientation.)
• Reduced areas of glass on northern facades
• Thermal mass (masse thermique) for storing heat
• Insulation and caulking (calfeutrage) of windows and doors
• Advanced glazing (triple thermal, etc.)
• Shading and ventilation solutions (including planting deciduous trees)

Passive solar buildings (construction naturelle), now sometimes called "green buildings" (bâtiment écologique) or "green houses" in the case of houses (maison écologique), look like other buildings but cost less to run and are more comfortable.

Proper orientation of the building will maximize winter heat gains (gains/apports de chaleur) and minimize winter heat losses. With good orientation, the need for auxiliary cooling and heating (refroidissement/chauffage auxiliaire) is reduced, resulting in lower energy bills.

In our northern climate, a combination of passive solar heating and cooling is required. Where ideal orientation is not possible, as is often the case in higher-density urban areas, an energy-efficient home can still be achieved with careful attention to design. Some people build a solar greenhouse (espace serre) as an addition to their house to take advantage of solar heat.

Solar radiation is trapped by the greenhouse effect created by correctly oriented (southeast facing) windows exposed to full sun. Proper insulation, windows and glazing type have a significant effect on the efficiency of this process.

Trapped heat is absorbed and stored inside the house by materials with thermal mass, which are usually masonry, such as stone, concrete, brick and tile. It is re-released at night when it is needed to offset heat losses due to lower outdoor temperatures.

Heat loss is minimized with appropriate window treatments and well-insulated walls, ceilings and attics. Eaves overhangs (corniche, etc.), window shades (stores) and fans (ventilateurs) are important in the summer to keep the heat out.

Thermal mass should only be installed in a well-insulated house. Thermal mass can be easily achieved with masonry. To ensure the comfort of your home in case of a power outage, masonry heaters (générateur de chauffage en maçonnerie), also called masonry stoves (foyer de masse^{Footnote 1}), are now a popular option. Masonry heaters store heat from combustion and redistribute it over the next 12 to 24 hours. Energy from a short hot fire is stored in the thermal mass and can provide heat all day long. Masonry heaters offer certain advantages over slow-combustion stoves: they burn half as much wood, produce less smoke and ash and practically eliminate the formation of creosote. They burn cleaner because of the high combustion temperature, which eliminates most of the pollutants contained in smoke.^{Footnote 2}

Source for French terminology: TERMIUM^® unless noted otherwise.