What Is Passive Solar Heating? How It Works and Limitations

Brief 

A passive solar-heated home needs no solar panels to heat or cool it. Rather, the energy used to heat and cool a house comes directly from the sun through skylights and windows. Some of that energy is then stored in the building’s walls and floors to be used at night and in cooler months.With good insulation and ventilation, proper materials, and thoughtful home design and siting, it’s possible to reduce heating and cooling costs partially or, in some cases, completely.

Insight

How Passive Solar Heating Works
One of the key virtues of a passive solar-heated home is how passive it is. Once the elements of a passive solar heating system are created, the home heats itself, quietly and with little human intervention. Here are some important considerations.

Energy Efficiency

The cheapest form of energy is the energy you never use. The first step in designing a home for passive solar is investing in energy efficiency.The keys to maintaining a passive solar home are well-sealed doors and windows, double or triple-pane windows, highly efficient appliances and water heaters, and excellent insulation.

By itself, a well-insulated home can save up to 20% of a home’s heating and cooling costs. A tightly sealed home is also a cleaner home, more resistant to air and noise pollutants, pests, viruses, and bacteria.

Good Siting, Good Windows

In the Northern Hemisphere, south-facing windows gain maximum exposure to the sun when unobstructed by trees, multi-story buildings, or other buildings. (Work with neighbors on a solar easement to increase your solar exposure.) For heating, six hours of direct sunshine in the middle of the day is recommended. For cooling in the warmer months, window shades, awnings, or other coverings help keep the house cool.

In colder climates, where southern exposure to the sun is more limited, tilted rather than vertical glass (such as in skylights on a sloped roof) prove more effective. Even in coastal climates, the diffuse solar radiation created by regular cloud cover can provide significant levels of heat that well-tilted windows can capture.