Creating a solar home or apartment

Some basic tips on how to get the sun on your (south) side.

by David Bainbridge

solar home or apartment will be much more comfortable and less costly to operate than average. Many existing buildings are "accidental" solar designs that work well and can benefit you with improved comfort and health and reduced bills. What should you look for?


The key to solar design is proper solar orientation which is usually free. A house or apartment should face due south (true south, not magnetic south). Most windows should be on the south (not blocked by other buildings), with few on the north, and even fewer on the east and west.

For rectangular buildings, an east-west orientation of the long side is preferred over north-south. In summer, the sun is high overhead at noon and rises and sets north of the east-west line. In winter, the sun is much lower at noon and rises and sets further south. With an overhang over the south windows to keep the high summer sun out, this unit or house will be warmer in winter and cooler in the summer than any other shape. Near the coast, subject to fog, the orientation is less critical. But in the east county, be wary of an apartment that faces east or west unless the windows are shaded.

If you wish to have a cool apartment, the coolest is usually the bottom floor on the north side of the building; the warmest in winter will be on the top floor facing south. The most uncomfortable are usually the east- and west-facing apartments on the top floor.


The keys to keeping a house or apartment cool in the summer are orientation and shading. An overhang and/or arbor will keep the high summer sun out but will let in the low winter sun. Windows on the east and west are difficult to shade properly. Shade screen is a step in the right direction, and is good for retrofits. East or west windows can benefit from exterior roll-down shades, solar control film or - as a last resort - interior aluminum foil panels which can be installed during the day.


Capturing cooling breezes in the summer requires careful window placement and interior design. Apartments with windows on opposite sides, preferably in the direction of wind flow, are most desirable. "Cave" type apartments are very hard to vent without large fans.

Providing privacy, safety, and good air flow is possible. Interior air flow can be increased by cutting doors one or two inches above the floor, and providing vents or windows above the doors.

A bathroom should have an exterior window, if possible. An interior bath should have a big, quiet fan. Unfortunately, most builders choose cheap, noisy fans.

Thermal mass

Heat from a sunny winter day or cool summer night can be saved with thermal mass inside the insulated shell. If you have a slab floor, linoleum with small area rugs will make for more comfort and reduced energy use than a wall-to-wall carpet. Internal mass can also be added with water-filled cans or drums - but only if the floor is strong enough.


Porches were a standard feature on old houses and provide many benefits for summer cooling and winter heating. An exterior porch makes it possible to add potted plants and exterior shades for windows. In Davis, California, we also required builders to include provisions for a clothes line for solar drying.

Ours is a mobile society, with many people changing residence every few years. If you find yourself about to move, a little care in selecting a new apartment or house can help keep you comfortable for free.

David Bainbridge lives in a naturally heated and cooled apartment that doesn't have an air conditioner and has never needed the heater turned on. He is the coordinator of environmental studies at United States International University and helped develop climatically adapted building codes for cities and counties and has conducted many studies on natural heating and cooling