Alternative heat energy

Passive solar

NRG-solarwall-1

Assiniboine Credit Union solar wall at 2659 Pembina Hwy, Winnipeg

There’s no shortage of sunlight in Manitoba. It has the potential to give us abundant, clean energy while cutting dependence on non-renewable energy.

Passive solar systems collect and use solar energy without using any external energy.

Most passive solar systems involve designing a building and its windows to make optimal use of sunlight for daylighting, space heating, and even space cooling.

On this page, we address the following aspects of passive solar heating:

Click a link in the list above to jump to that topic on this page.

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Windows

Buildings gain heat through south-facing windows. Basically, sunlight passes through a window (south-facing windows are most efficient), hits an object, energy is absorbed, and is converted to heat.

Once in, a well-insulated and air-tight building will help keep the heat in. The heat can then be distributed with a ceiling fan or forced-air furnace fan. Using building envelope upgrades alone, up to 25 percent of a building’s heating needs can be met with passive solar techniques. (1)

Too much south-facing glass can make the building too warm – and then increase cooling costs. There is an optimal amount of south-facing glass a building should have. At our latitude, the area of south-facing windows should be no more than about 8% of the heated floor area. This percentage can be increased by increasing the thermal mass in the room.

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Solar walls

A solar wall is an exterior wall used to pre-heat air entering a building’s heating and ventilation system.

The solar wall is south or south-east facing. It is usually black-coloured and basically hollow. Fresh air enters through perforations on the surface of the wall. The black exterior absorbs energy as the sun shines on it. This energy heats the air as it rises up within the wall. At the top of the wall, the air is drawn into the building’s heating and ventilation system. This system can preheat the air by as much as 30oC. (2)

Here is a 3-min video about a passive solar wall that was installed on the visitor reception centre at Lower Fort Garry historical site in Selkirk, Manitoba by Parks Canada.

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