Passive solar home design Passive solar home design © Creative Commons

Passive solar home design

Ecohome June 5, 2012, 7:32 a.m.
Mike Reynolds

With a southern orientation and well placed windows, passive solar homes can potentially reduce heating requirements by an easy 25% without adding any cost.

Passive solar is so aptly named because there are no wires, panels or batteries and nothing to break down. It's just about design, and it isn't a new concept. Humans around the globe have been incorporating passive solar design features into their homes for thousands of years.

Active solar refers to any system of solar panels whether it be photovoltaic power generation, or thermal solar where liquid passing through tubes collects heat to be redistributed through your house.

 
According to NASA, every day the sun provides the earth with 10,000 times the total energy consumed by humans. A passive solar house is simply one that has been designed to take advantage of that.
 

Passive solar heating is yet another green building design feature that will save you money while improving your quality of life. Artificial Lighting in the built environment affects natural human biorhythms and can lead to fatigue, and reduce our ability to concentrate.

Whether we realize it or not, we are all directly affected by the amount and quality of light we are exposed to. As most of our daylight hours are spent at work, the office environment has a particularly heavy impact on us.  As a testament to the benefits of natural light, LEED certified commercial buildings that offer outside views and natural light report higher productivity and worker satisfaction.

How passive solar heating and cooling works:

There are two dates that form the cornerstone of passive solar design, December 21st and June 21st when the sun is at its highest and lowest points.

Window size and placement along with overhangs and shading are determined based on these two dates to ensure maximum exposure at midday December 21st, and maximum shading at midday June 21st.

Passive solar window design
Passive solar window design. © Ecohome

These two dates are important because while you want to absorb as much heat as possible in winter, insufficient shading in summer can make houses unbearably hot and increase cooling costs, which will negate a lot of the energy savings from heating.

In the design phase you can determine what parts of your floors and walls will be exposed to the sun, and place materials there that will absorb thermal radiation. Darker materials with heavy mass like concrete, stone or brick will absorb the most heat. For walls you can simply add a second layer of drywall (or more), if you want to keep a traditional look.

 A high quality Window choice is important, and to truly invest in this concept you are best to install triple pane gas-filled windows with low-e coatings to ensure that the heat gained in the daytime outweighs the heat lost at night.

It's important to keep in mind that passive solar heating is not something that should intimidate you in the design phase, and it isn't an 'all or nothing' concept. It is an ancient and relatively easy concept that has been overlooked in home construction for generations.

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