Just What is Passive Solar Design, and is it Right for You?

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The determination of what constitutes a ‘green home’, is how well it interacts with the surrounding environment. The perfect example of this are homes and businesses which utilize passive solar heating. Passive solar heating keeps buildings cool in the summer, and warm in the winter, simply by using the sun’s radiant energy. Some examples of well known buildings which use passive solar design are the Energon, in Ulm, Germany, and the Solar XXI building located in Lisbon, Portugal. If you’re on the fence as to whether to design your home or business using conventional heating and cooling units or passive solar design, then the first step is to become familiar with just what passive solar design is.

What Exactly Is Passive Solar Design?

When we talk about passive solar design, we are simply mean using the sun to heat and cool a living area. The moment the morning sun hits a building, the materials used in it’s construction utilize this solar radiation. This translates into the ability of a building to convert the sun’s radiant energy to thermal energy. Some of this converted energy will be used to heat the building, while another portion will be stored for later. As you can probably guess, this type of system is not something you can simply add to your home, like a boiler or air conditioning unit. Rather, the elements involved in passive solar design are integrated into the building itself.

Designed Around the Movement of the Sun

As stated, this system takes advantage of the environment, and is designed around the movement of our sun. Since the sun rises in the east, and sets in the west, buildings which have windows on the south of the building are capable of collecting the solar radiation most of the day. Passive solar heating also takes advantage of the seasonal changes in the sun’s movement. During the summer season, the sun’s path is higher than it is in the winter. Knowing this, designers of passive solar systems incorporate certain roof or window overhang designs which allow the home to benefit from as much winter sun as possible, while the overhang shades the windows in the summer. While the process is designed for new buildings, if you have your heart set on having passive solar design for your existing building, know that it is possible to retrofit your home or business.

Passive Solar VS Conventional Systems

As you can see, the passive solar design system uses  building materials and design elements to transmit, absorb reflect the sunlight. whereas traditional heating and cooling systems utilize mechanical and electrical devices to control the heating and cooling of a home or business environment. These conventional systems utilize air conditioning units, boilers and other heating units  to transmit the heat throughout the living space.

Traditional systems are not part of the home, and they are subject to be in need of installation, maintenance and repair. Something to consider when choosing between the two, as passive solar design is free of maintenance and repair. As passive solar systems take the sun’s radiant energy, utilizing seasonal movements of the sun to heat or cool a building, without the use of any electrical or mechanical devices, it could save you quite a bit in the long run.


Main Parts of Passive Solar Design


The aperture is the opening in a building, which allows sunlight to pass through. Generally, these are the building’s well insulated, south-facing windows. Since this is a passive system, it’s crucial that these south-facing windows are not blocked by window overhangs, other buildings or trees. It also helps if they are well insulated.

Absorber and Thermal Mass

This absorbs the sunlight, or radiant energy so it can be converted to thermal, or heat energy. This is where the energy is stored for future use. The thermal mass can usually be found in the buildings floors and walls. Here, energy is absorbed, stored and slowly released during the night. Whereas the active solar system separates the absorber and  thermal mass, in passive, they are incorporated in the same units, meaning the walls and floors. In order to facilitate the absorption of radiant energy, the floors and walls are generally of a dark color.

Distribution and Controls

As the name suggests, distribution is the movement of heat from the storage areas, such as the walls and floors to the rest of the building. In a pure, passive solar design system, the energy is moved via three methods: Radiation, natural convection and conduction. However, many homeowners incorporate fans or blowers to assist in the circulation on an as needed basis.

Controls refer to devices such as dampers, vents, roof overhangs, or awnings. All of the aforementioned controls work to help to control the circulation throughout the seasons. Some homeowners add thermostats that work to operate the fans or dampers. Both active and passive solar designs also incorporate a backup heating system. These backup systems are not solar systems.


Final Thoughts

Homes and businesses which inhabit buildings with passive solar design use the energy supplied by the sun. This method of heating and cooling living space is the least expensive way to regulate the temperature of your home or business. . We all know how expensive it can be to have heating and cooling devices repaired or replaced. In fact, repairing and purchasing standard HVAC system can run into the thousands. Plus, there are the yearly maintenance costs involved. Passive solar design eliminates all of this. If you are considering having a new home built, or would like to invest in having your present home’s heating and cooling system replaced by a passive solar design

There’s no question about it, passive solar design saves you a good deal of cash. Since the elements are integrated into the building there’s no need to spend money on the purchase, upkeep and repair of heating and cooling units, not to mention the absence of those pesky monthly utility bills. As long as the sun’s in the sky, you’ll have the energy you’ll need.  In fact, you can take the money you’ll save on utility bills and invest it in a mutual fund for your retirement!

However, depending on where you live, some modifications may be necessary depending on the level of comfort you desire. While passive solar design can provide some warmth on a wintery day, some homeowners opt to have an additional heating unit installed. This can be in the form of active solar design or other method.



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