Passive Solar Energy Houses

What Is Passive Solar Design?

• Passive solar design does not use mechanical or electrical devices to move solar heat. The walls, windows, and floors are designed to collect, store and distribute solar energy in the form of heat in winter and reject solar heat in the summer. The basic difference between this and traditional house design is that a passive solar house is designed to take advantage of the local climate. Passive solar houses are energy efficient, comfortable and aesthetic.

The Five of Elements of Passive Solar Design

• The aperture is the collector of the sun's energy. It is the large glass window or area where the light enters; the aperture should face within 30 degrees of true south and should not be shaded by buildings or trees. The absorber is the hard surface of the storage element; it could be a masonry wall, floor or partition or a water container. It must be situated in the direct path of the sunlight so that the sunlight is absorbed as heat. Thermal mass is the materials that retain the sunlight's heat.The thermal mass is below or behind the absorber. The distribution in passive solar design will use three natural heat transfer modes: conduction, convection or radiation. Sometimes fans or blowers assist distribution in passive solar. The last element, control, refers to the roof overhangs, the awnings or low-emissivity blinds. Supporting elements of design include location of windows, insulation and air sealing and auxillary heating and cooling.

Passive Solar Techniques

• Direct gain refers to sunlight entering and being absorbed by masonry walls or floors, which later radiate the heat back into the house at night. Indirect gain involves using a trombe wall 8 to16 inches thick that has the glass mounted in front of the wall on the south side of the house.The sunlight's heat is absorbed, stored and then released over several hours when the indoor temperature falls below the wall's surface. Isolated gain refers to a sunspace that collects the sun's heat through glass windows, absorbs and stores the heat in the masonry floor, then distributes the heat, sometimes with the aid of vents, fans or windows. All techniques are used within the five elements of design. Of course, the locale can influence the homebuilder's choices.

Caution

• Use an experienced solar homebuilder, as marrying the design process and the techniques is contingent upon the climate locale, and an experienced builder understands this; he has the skills to execute the solar passive design successfully.