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  • Writer's pictureBrian Harbin

How Does Passive Solar Heating Work?

Passive solar heating enables homeowners to avoid the costs associated with fossil fuels by collecting, absorbing and distributing solar energy via their windows with the use of materials that keep hold of the day’s heat and then have it dispersed at night-time. This means that a home can be kept at a comfortable temperature all day, every day, even in areas that would normally be cool.

Passive solar heating is so named due to the fact that all that is needed to make it happen is sunshine, not even solar panels or any other such technology.

How does it work?

There is a five-step process in how passive solar heating actually works. The first step is to allow north-facing windows in a home to allow sunshine to shine through them; this is referred to as the collector (aperture) stage. Framing, glazing type, shading and window orientation all have an impact on how efficient this process will prove to be.

Once the energy has gone through the collector it is then absorbed by the absorber, which is a dark layer of paint on the top of a thermal mass surface that is able to hold in heat. The solar energy that is being sucked up by the absorber is then sent to the thermal mass, surfaces that can take in and keep heat such as bricks, ceramic tiles, concrete and stone. The sun usually burns brightest between 9am to 3pm and the thermal mass will be able to store that energy for use during the evening and at night.

Passive solar heating enables that heat to then be released into the home in several different ways. Radiation is heat that travels as waves akin to a microwave, while convection sees the heat simply move through the air.

Conduction on the other hand simply transfers heat by touch.

Even once heat has been released it needs to be able to stay in the home rather than simply dissipate. Control is a way of dictating the whole heating process including overheating and its opposite, under-heating. Control refers to a process system that has a number of factors all working together including roof overhangs, sensors to detect heating problems and vents.

Passive solar heating works along with passive shading, which allows for maximum solar gain during winter and prevents overheating during summer. The simplest way to achieve this is with well designed eaves overhangs or having specific glass areas oriented in a northerly direction.

Passive shading features are able to control the entry of wind and sunlight into the home.

The design of floor plans should make sure that the living areas used the most in the day are facing north and get the best solar access during winter.

Heat loss can be reduced with appropriate treatments on windows and ceilings, raised floors and walls being well insulated.

Passive solar heating is a superb investment when building or purchasing a new home and can save hundreds of dollars per year.

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