Passive Solar Design


What is a Passive Solar House?

In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer. Passive solar homes are more energy-efficient and help reduce your home heating costs. Contrary to popular belief, passive solar homes can be cool in the Summer as well as beautifully designed and aesthetically stimulating.

Although passive solar design is simple in methodology, Greenovision is trained and experienced in passive solar strategies and will ensure that your home’s solar potentials are utilized most effectively. The key principles of passive solar design are as follows:

  1.  Building site properties must be evaluated and exploited.
  2.  The home must be designed so that it captures the suns solar radiation.
  3.  The home has a floor plan that is designed to be fairly open in order to promote convective air cycles.
  4.  Building materials must increase in mass (weight) for heat storage. i.e. masonry, concrete, stone, thick tiles.
  5.  Mass is located  in correct locations in regards to solar aspect.
  6. Windows or apertures are at correct heights and face due South.
  7. Building roof overhangs to the South are deep enough to shield the sun from the interior during the summer months to prevent overheating.
  8. An aggressive strategy of cross ventilation through windows as well as an air exchange system are designed into the building.
  9. Windows are glazed with the correct type of glass. This type will change depending on its aspect i.e. facing North, East, South, West.


Every building site has its potentials and weaknesses in regards to utilizing the sun’s energy. Sites that are sunny and fairly free of tall coniferous trees, especially to the Southern aspect, have great passive solar potential. During the Summer, deciduous trees on the South side of the home help screen the sun to reduce excessive solar gain. During the colder months, deciduous trees drop their leaves, allowing the lower angled sun rays into the home. We typically design homes that combine hydronic radiant heating with passive solar heating for maximum efficiency. With this approach, the heat is passively collected, but actively distributed throughout the home.  So in a sense Greenovision mostly utilizes a hybrid method.  We call this ‘Sun Smart Radiant Heating’ . SSRH sensibly captures the suns energy when it shines, but has the added benefits of distributing the heat uniformly through out the home and added heating for when there are long stretches of cloudy days or extreme cold.

For more information on passive solar home design, please see “Reduce Your Heating Costs” on the Greenovision blog. You can also read “Bring on the Sun: Homes keen to solar rising in Bozeman,” an article we wrote for The Bozeman Magpie.