My in-laws are ahead of the game!  When they built their home in sunny Central Oregon 25 years ago, they positioned the house just right considering the arc of the sun’s travel through the sky.  In the morning, when its cool, they throw open the doors and allow fresh breezes inside.  Then, when the sun warms things up, the doors shut and blinds go down until the sun does.  Strategically-placed trees also provide shade, making their house a prime example of passive solar energy at work.

How can you do this yourself?  To use passive solar energy, building elements such as walls, floors, roofs, windows, roofing and siding, and landscaping are included specifically to manage heat generated by sun.  Consulting a professional with expertise in passive solar energy will be worth it.  He or she can include solar heating designs that will allow your building to trap and store thermal energy from direct sunlight.  Passive solar energy designs also have a cooling component to minimize the effects of solar radiation through shading or generating air flows with convection ventilation.

Here is a short video that illustrates a “fly around” of a home designed and built for passive solar energy:

Now, come with me to France, where we can see an actual home built for passive solar energy in this video (no translation needed because the house speaks for itself!):

Perhaps the most important elements of a building design for passive solar energyare the windows, insulation and landscaping.  These all play a role in daylighting, passive heating and passive cooling – the primary solar energy elements.

Image from Solcomhouse.com

Daylighting: Reduce your overall electricity bill simply by using the natural light from the sky and not just the daylight. Not only will the light create a more pleasant environment, but A/C costs will also be lowered when you use less lighting.  A considerable amount of heat is generated by light bulbs.

Passive Heating: Not surprisingly, you can heat your home simply by maximizing the absorption of thermal heat from the sun.  The best window orientation to accomplish this goal is towards the south. You can then heat the entire building and not just the room in which the sunlight is entering.  For passive solar heating you should construct a ratio of eight percent window to floor area on south-facing walls.  Adequate insulation is needed to minimize heat loss.  With high performance windows that have insulated frames, multiple glazing, low-e coatings, insulating glass spacers and inert gas fills, heat loss can be reduced up to 75%.

Passive Cooling:  Those of us that live in warmer climates will want to use opposite techniques to maximize passive cooling (i.e. fewer, smaller south-facing windows).  Installation of shading devices such as awnings and/or shady trees should be considered in order to reduce solar gains by up to 90%.  Again, good insulation is required.  You should also consider glazing on windows and reflective walls and roofing materials.  Position your home to maximize cross-ventilation (consider direction of prevailing winds).  In the morning and evening, you can open things up to allow cooling breezes through.

Even if your home is already built, you can still incorporate passive solar energy design elements and practices.  Take advantage of natural cooling and heating simply by opening your shades in the morning, closing them in the afternoon and strategically placing trees and shrubs to provide shade, like my in-laws have done.  Believe me, my husband and I learned by their excellent example.  Most importantly, enjoy the extra “green” in your pocket as a result of passive solar energy design.