Passive solar heating systems utilize the building’s materials to collect and then radiate heat during seasons when the sun is not present, such as at night.

In the construction of these systems, south-facing glass and thermal mass are required to absorb and store heat. The heat is then emitted back into the space as needed to maintain comfort levels.

George F. Keck, an early pioneer of passive solar homes in the 1930s and 1940s, designed and invented the all-glass “House of Tomorrow” for the 1933 Century of Progress Exposition in Chicago and wrote that it was warm inside on sunny winter days before the furnace was installed.

How Does Passive Solar Heating Work?

In solar passive heating design, the absorber is a surface that is exposed to a lot of sunshine (such as a wall or floor).

Since absorbers are frequently dark surfaces, they allow the maximum amount of sunlight possible to enter.

The heat is stored in a thermal mass below or adjacent to the absorber after it has been absorbed.

After the sun sets, the stored heat in the thermal mass is gradually released back into the space, providing warmth long after the sun has disappeared.

In order for a passive solar heating system to work properly, there must be a good seal around all doors and windows to prevent heat loss.

Passive Solar Design Basics

There are 5 main types of passive solar heating systems:

  • Aperture/Collector
  • Absorber
  • Thermal mass
  • Distribution
  • Control


An Aperture/Collector is a large south-facing glass area that allows the sun’s energy to enter the home.

The size, shape, and angle of the aperture/collector can vary depending on the climate and the specific needs of the home.

The apertures should be within 30 degrees of true south and not be shaded by other buildings or trees from 9 a.m. to 3 p.m., daily, during the heating season.

Related: Do Solar Panels Work Through Glass? (MAYBE?)


The surface of the storage container is blackened. The exposed surface faces direct sunshine. When sunlight shines on the surface, it absorbs heat.

Thermal mass

The materials that actively keep or store the heat produced by sunlight. The absorber is a surface that is visible, while the thermal mass is the substance beneath and behind it.


This is the way in which solar heat is transported across your home after it has been collected and stored.

Convection, radiation, and conduction are the only three natural heat transfer processes available in a solely passive design.

Fans, ducts, and blowers may be used to distribute heat throughout a property using fans and ducts in some circumstances.


During the summer, overhangs can be utilized to block the aperture space from the sun.

Electronic sensors, such as a differential thermostat that activates a fan, are also used to regulate both under and over-heating.

Operable vents and dampers allow or limit heat flow; low-emissivity blinds; and awnings all help to keep buildings cool.

Advantages and Disadvantages of Passive Solar Heating

Advantages of Passive Solar Heating

  • Environmentally friendly
  • Produces buildings with lower energy costs.
  • Produces buildings with low maintenance.
  • Can create a space of superior comfort.
  • Great aesthetics
  • Flexible with both small and large houses

Environmentally friendly

Passive solar heating is one of the most environmentally friendly ways to heat a house.

The sun is a free and renewable resource, and using it to heat your home doesn’t produce any pollution or greenhouse gases.

Produces buildings with lower energy cost

This system can save you money on your energy bill because it reduces the amount of energy needed to heat your home. In fact, a properly designed passive solar home can meet a substantial amount of heating needs from the sun.

Produces buildings with low maintenance

Passive solar heating systems don’t have any moving parts, so there are few maintenance concerns.

The only regular maintenance required is to keep the south-facing windows clean so they can continue to absorb solar energy effectively.

Can create a space of superior comfort

Passive solar heating can make a space more comfortable because it heats the building evenly and slowly.

This is in contrast to conventional heating systems, which often create hot and cold spots and can produce drafts.

Great aesthetics

Aesthetics are an important consideration in any home design, and passive solar homes can be very attractive.

The large south-facing windows that are necessary for effective solar gain can let in a lot of natural light, making the interior of the home bright and cheerful.

Flexible with both small and large houses

Passive solar heating can work well in both small and large houses.

In a small house, the entire south-facing wall can be used for solar gain, while in a larger house, only a portion of the south-facing wall may be necessary.

Disadvantages of Passive Solar Heating

  • Cannot meet all heating requirements
  • A south-facing wall is needed
  • Planning is difficult if your neighbors are close
  • Coordination with the architect is also required
  • Inability to control the temperature directly.
  • Features will either increase or decrease the temperature due to the outdoor conditions.

Cannot meet all heating requirements

Even though this type of heating system is extremely effective, it cannot meet all heating requirements for a home.

This is because the sun isn’t always shining, and at night or on cloudy days, the system won’t work as well.

A south-facing wall is needed

For passive solar heating to be effective, a south-facing wall is necessary.

This wall should have a large number of windows to allow solar gain, but it should also be well insulated to prevent heat loss.

Unfortunately, this isn’t always possible, depending on the orientation of your property.

Planning is difficult if your neighbors are close

If you live in a densely populated area, it can be hard to find a property with a south-facing wall that isn’t obstructed by trees or other buildings.

Coordination with the architect is also required

If you are doing a self-build, a lot of communication between you and your architect will be necessary to make sure the passive solar heating system is designed correctly.

Inability to control the temperature directly

One of the main disadvantages of passive solar heating is that you can’t control the temperature directly.

The amount of heat generated by the sun varies depending on the time of day and the weather, so it can be hard to maintain a consistent temperature.

Features will either increase or decrease the temperature due to the outdoor conditions.

There are some features that can help to regulate the temperature, such as blinds and thermal mass, but they will also be affected by the outside conditions.

For example, on a hot day, the thermal mass will absorb heat from the sun and make the interior of the home too warm.

Does Passive Solar Make Financial Sense?

If you have a large south-facing wall that will allow you to install several window panes, then passive solar might make financial sense.

The payback period for Passive Solar Heating is around 7-8 years.

How Can It Affect Net Zero Energy?

Passive solar heating is a great way to reduce your energy consumption and lower your carbon footprint.

If you are able to combine passive solar heating with other green technologies, such as solar panels and wind turbines, you can create a net-zero energy home.

A net-zero energy home is a home that produces as much energy as it consumes, making it environmentally friendly and very cost-effective.

What Is The Future Of Passive Solar Heating?

The future is bright for passive solar heating.

As more people become aware of the benefits of this technology, and as the cost of traditional energy sources continues to rise, passive solar is likely to become more popular.

In the future, we may see more homes that are designed specifically for passive solar heating, with larger south-facing windows and thermal mass features built into the walls and floors.

We may also see more passive solar heating systems that are integrated with other renewable energy sources, such as solar panels and wind turbines.


Is passive solar energy renewable?

Yes, passive solar energy is a renewable resource.

The sun is a constant source of energy, and as long as the sun continues to shine, we will be able to use passive solar heating to heat our homes.

Is passive solar heating efficient?

Yes, in fact it is the most efficient way to heat your home.

Other methods, such as using a furnace or electric heater, are not as efficient because they convert energy into heat, which is then lost to the environment.

With passive solar heating, the sun’s energy is used directly to heat your home, so there is no energy loss.

Can passive solar heating be used for cooling?

Yes, passive solar cooling is possible since you are using your windows as way to gain heat during the day, and then using the coolness of the night to radiate that heat out.

About the Author

Passionate about helping households transition to sustainable energy with helpful information and resources.

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