More Straw Bale Building. Peter Mack

rarely addressed, and when it is addressed, it’s as though it’s a specialty concern. It should be fundamental: if you’re undertaking a building project, please don’t ignore the sun!

      Ever watched a cat or dog stretch out on the floor in a pool of warm sunlight? Passive solar design can maximize your home’s exposure to those warm rays and give them a chance to heat your home in the colder months. At the same time, proper passive solar design ensures those same rays are kept out when you are trying to keep your home cool in the summer. By simply taking account of the sun’s position in the sky, you can lower the cost of winter heating and summer cooling dramatically, while improving occupant comfort.

      Passive solar design is premised on the changing position of the sun from morning to night (east to west), and from winter equinox to summer equinox (low on the horizon to high). At each time of day and in each season, we want our buildings to coordinate their performance with the sun’s position.

      7.1: This is a good example of effective passive solar design. South-facing windows on both floors are shaded in summer and open to the sun in the winter. The “eyebrow roof” is slanted at a good angle for mounting solar panels.

      There is no one-size-fits-all strategy for appropriate passive solar design. Much will depend on your geographical location (your latitude), your climate, the specifics of your building site, and your daylighting needs inside the building.There are three basic elements to consider in passive solar design:

      • building orientation and shape

      • window placement and shading

      • occupant needs and movements

      Building Orientation and Shape

      The classic passive solar strategy calls for a building that is oriented so its longest side faces south (reverse for the southern hemisphere), creating a building along an east-west axis. This allows you to maximize your south-facing windows for passive heat gain in the winter. It is a good strategy, and when the site and occupant needs allow for such a shape, it is simple and effective.

      However, a lot of building sites do not allow for this long and skinny approach. But that doesn’t mean you have to give up on passive solar design. There are many building shapes, some simple, some complex, that allow for good use of the sun. Even on sites where southern exposure is limited or the building is constricted by lot size, there are ways to maximize passive solar aspects.

      When siting a house to face south, simply locate the sun around noon. That’s the direction you want! A compass will point you in a direction that is not quite true solar south, since magnetic north and true north are not aligned perfectly. If any bias is to be made away from true south, it is best to shift a bit to the east to maximize your morning exposure and minimize late afternoon overheating.