Capturing Energy From the Sun

First off, let's make sure we're clear that the topic of this article is about passive solar energy. If you're interested in active solar power, read this article.

The idea of using passive solar has been known since prehistoric times, and it is considered by many to be the first basis of sustainable shelter. In a nutshell, passive solar uses obvious design to harness the sun's energy without any complicated equipment. It allows the use of solar heat as solar heat, without loss of efficiency in conversions. The major advantage of its simplicity is that it can be done as part of a remodel, and it can be done in stages.

Facing South (In the Northern Hemisphere)

The most basic thing you can do, and most effective, is to install southern-facing windows to allow the low-angled winter sun to pour in. If the sun can't get in, there isn't any solar heating at all. The glass in most home installations allows the best sunlight transmission up to a 15 degree angle from south. At greater angles, too much of the energy will be lost to reflection.

Shadowmakers

Good planning of sun angles can also be used to good advantage where summers are hot and winters cold, through the use of overhangs. A roof eave of the right dimensions, set just the right distance above a southern-facing window will let that low winter sunlight to come into the interior, while it acts to block the high-angle summer sunlight to keep those same windows shaded. Talk to an architect about calculating the geometry that will accomplish it, and you'll have lower heating and air conditioning bills all year.

Storage of Heat Energy

There's no evading the fact that the sun only shines in the daytime (unless you're so far north or south that the sun doesn't shine at all in the winter, in which case passive solar isn't going to provide any heat for your house in the winter). To keep your house heated during those long winter nights, you will need some way to buffer the sun's energy. to do this, install something that absorbs heat where the sun will warm it up when it can, and it will radiate heat during the night, keeping you warm. Thermal mass can be concrete covered with tile, preferably dark, or anything else which will soak up the sun's energy.

Use Insulation

Don't let it get away. Insulate the walls, be sure all the windows are leakproof, and cover your window openings with insulated drapes or thermal protective coatings.