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Passive Solar Cooling and Heating

Save Energy and Keep Your Home Cool

Learn more about passive solar heating and cooling and how you can cool and heat your home without using energy.

Passive solar heating and cooling, sometimes called passive solar design, is the process of using distinct building techniques to help regulate temperature by using solar energy beneficially to improve energy efficiency. In these systems, the building, or an element of it takes uses the natural characteristics of materials when exposed to sun. Generally, these systems are simple, with few moving components, thus requiring minimal maintenance.

The engineering needed to make these systems includes carefully choosing materials for the construction envelope – including the building’s floors, roofs, walls, and glazing materials – and selecting their proper orientation. Passive heating and cooling captures or shades against solar rays.

How They Work

Solar heating and cooling use natural methods such as conduction, convection, and radiation to warm or cool down a building. They require little to no outside energy to work and contribute to a home’s energy efficiency. When the sun shines, solar rays heat a building. This solar energy is transformed into heat and transported by warm air or water into the building. By capturing or shading against this radiation, you can control a home’s temperature.

When summer is nearing, it is time to try and keep it cool. Passive solar design is one of the most cost-effective ways to stay cool in the summer. And guess what? Doing so can also help you stay warm during the winter.

Passive solar design involves using the sun to heat a building during the winter while blocking the sun out during the hotter months to keep it cooler. While you can use these techniques with solar power, they do not need to be. Instead, passive solar cooling focuses more on how the home is built and used.

To keep a home cool during the summer, you should cover south-facing windows during the day. To keep the sun shining through the windows and thereby heating indoor surfaces, use blinds, shutters, curtains, or sunblock window films. Awnings are also great during the summer when the sun is high in the sky (during the winter, the sun is at a lower angle and can still shine through the window). When it is cool outside, you can open the window coverings at night. Avoid having west-facing windows.

Another way to keep the sun out is by having deciduous trees or bushes in front of the south sides of buildings (these can be helpful, even if you do not have any south-facing windows.) The added benefit of deciduous trees is that they have lost their leaves by wintertime, meaning that the sun can shine through your home and heat the interior surfaces.

Another method of heating and cooling a home is called direct gain. Direct Gain involves having good thermal mass in the room. Dense and heavy materials like stone floor slabs and concrete walls, and masonry materials are generally best (they absorb and release heat slowly).

Still, any material in the home, including furniture, which absorbs, and stores heat is considered thermal mass. The best thermal mass is in direct sunlight and of a dark colour.