passive solar heating

Passive solar heating: an overview

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Solar energy isn’t just useful for generating electricity; if you’re in the process of designing a new building, one of the most economical ways to take advantage of sun’s power is to design your property with passive solar heating in mind.

What is passive solar heating?

Passive solar heating is using the sun’s rays to heat a living space by exposing the area to sunlight. Passive solar buildings take advantage of how the sun moves throughout the day (with attention to seasonal changes in sunlight) to warm living spaces, without requiring any mechanical devices or fuel to do so.

Passive solar designs typically involve five important factors: an aperture for the sunlight to pass through, absorbers and thermal mass to absorb and retain the heat, distribution for heat circulation, and a fixed control that will provide shade during the summertime.


The apertures in passive solar buildings are often large windows. In some cases, designers will build a property that has an entire wall made of windows to maximize exposure. Sunlight will flow through the windows throughout the day, heating the living space. These windows often have a specialized coating that will reflect harmful ultraviolet (UV) rays away from the glass, preventing them from entering the space.

Absorbers and thermal mass

As sunlight is flowing into the room, absorbers and thermal mass will capture and retain the heat so that it warms the space into the evening and night after the sun goes down. In passive solar heating design, the absorber is a surface exposed to a lot of sunlight (such as a wall or floor). Absorbers are often dark surfaces so that the maximum amount of sunlight possible is soaked up. Once the absorber captures heat, the heat is retained by a thermal mass below. Some common materials that absorbers and thermal mass components are built of include concrete, ceramic tile, brick, or stone because these materials have a high heat capacity due to their density.


Throughout the day and into the night the sun’s heat is distributed throughout the living area. This can be done mechanically with small fans or blowers, but they are not necessary – heat will naturally move throughout spaces. Whether you have passive solar heat or not, warm air will move towards colder areas and disperse.


Lastly, the control component of a passive solar building will shade windows when the sun is in a higher position during the summer months. This is a vital component of passive solar heating design, especially if you don’t want your living space to be too hot during the warmer months. Different control components include awnings or roof overhangs, blinds, and shutters. These control elements can also help offset any costs of cooling your home in the summer, as they help keep your living space cool and can reduce your air conditioning needs.

Benefits of passive solar heating

There are a number of benefits of using passive solar heating. First and foremost, it can save you money on energy bills. By using passive solar energy, you’re taking advantage of a natural process and utilizing free, renewable energy from the sun to warm your building. This allows you to dramatically decrease (or possibly eliminate) your purchase and use of gas, wood or electricity for heat, saving you money. There are also no operating costs for passive solar heating, while other traditional heating technologies have a limited lifespan and require maintenance over the years.

Passive solar heating is also environmentally friendly – there are no greenhouse gas emissions or pollutants released into the air as a result of sunshine passively entering your living space. Most traditional methods of heating a building (such as furnaces, electric resistance, or space heaters) use fossil fuels for power, which release greenhouse gases and pollutants into the air when used.

Passive solar designs also have a number of comfort benefits. For one, there is no noise coming from rumbling radiators or furnaces when you use passive solar heating. You’ll also get natural light in your living space and better views from your home due to the use of large windows.

Considerations for passive solar heating design

Not every property is perfectly suitable to take advantage of passive solar energy. If you’re building a property and looking to adequately heat your property with the sun’s thermal energy, here are some important factors to keep in mind:

Insulation and energy efficiency

In order for a passive solar design to be as effective as possible, your building needs to be well-insulated. This will enable the sun’s heat to stay in the designated space for as long as possible. If your home isn’t properly insulated and has lots of air leakage, passive heating won’t be a sufficient source of heat during colder months.

Obstructions to sunlight

Large windows won’t do a lot of good in providing passive solar heat if there isn’t a lot of sunshine streaming through them. Large trees, hills, or nearby buildings may be situated south of your property, therefore blocking sunshine throughout the day. Even if you’re building a home in an area that currently receives an abundance of unobstructed sunshine from the south, you have to consider if these conditions will remain the same down the road: how large will smaller trees end up growing? Is there any chance your neighbor may invest in a property addition that would prevent your solar access? Before investing in passive solar design, make sure you’ll have access to sunlight for the foreseeable future.


Your geography is also an important factor. Passive solar heating is reliant on the position of the sun on a property throughout the various seasons, and this position will vary depending on your location. In the northern hemisphere, apertures should face south, while northern facing apertures are ideal in the southern hemisphere. The size and position of your control component may also depend on your latitude, as the angle of sunlight on a given date will be different in southern California than further north in New England. An architect that’s experienced with passive solar heating expert will recommend an awning or overhang that will be the optimal size to ensure that you get the right amount of shade during the summer.

Designing your property for passive solar heating

One downside of passive solar heating is that if your property was not originally built with it in mind, it can be an expensive renovation. Because passive solar requires a deliberate design in regards to building location, apertures, and construction materials, it’s easiest to take advantage of it if you’re constructing a new building and design it accordingly from the get-go.

That being said, if you are planning an addition to your home, there are steps you can take to utilize passive solar energy even if it’s not suitable to be your primary heating system. Many property homeowners consider using passive solar design in isolated additions to their homes like a sunroom.

If you’re just starting out in designing and building new construction, now is the perfect time to consider passive solar heating for your property. During the design phase of your new construction project, it’s best to work with a qualified green building architect or designer who has experience with these types of heating systems to ensure you’re receiving the maximum amount of benefit the sun has to offer.

If you’re interested in seeing passive heating in action, take a look at case studies of passive solar on EnergySage. These case studies include pictures, testimonials, and advice straight from property owners utilizing passive solar design themselves.

If your property isn’t suitable for passive solar heating, consider installing solar photovoltaic (PV) panels as another option for saving money on energy bills. By joining the EnergySage Solar Marketplace, you can obtain multiple solar quotes from pre-screened, vetted installers to compare. These custom quotes will include savings estimates that take into account electricity rates in your area, how much electricity you use, and the details of the proposed solar panel system.

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