As the cost of fuels used to heat buildings has increased in recent years, much interest has developed in using readily available solar energy. Numerous systems have been developed for heating either water or air with the thermal energy provided by solar radiation.
Several of these systems circulate air along a wall of the building that has been fitted with a solar energy collector panel. Among them are the structures disclosed in U.S. Pat. No. 3,832,992 to Trombe et al., U.S. Pat. No. 4,147,300 to Milburn, U.S. Pat. No. 4,069,809 to Strand, U.S. Pat. No. 4,217,883 to O'Hanlon, and U.S. Pat. No. 4,327,708 to Taylor.
Trombe, Milburn, and Strand disclose systems that use a glass or plastic exterior wall that is at least translucent to sunlight, with heavy building material such as masonry or cement used to absorb the solar energy. The air from the interior of the building is heated as it passes over the solar-heated building material and thermal energy is radiated from the building material. The patent to O'Hanlon discloses a system that uses a metal screen instead of the heavy masonry or cement, but still uses a specially constructed wall of a rigid plastic foam and a translucent or transparent sheet of material over the outside surface. Systems such as these are unattractive to many people, particularly individual homeowners, because of the need for special and expensive construction of the wall on which the system is mounted and because a wall with an outer surface made of glass or similar material is aesthetically displeasing. Furthermore, these systems frequently can not be installed on already existing buildings because of the need for special wall construction.
The system described in the patent to Taylor provides a plurality of parallel horizontal air channels, each of which is defined by a metal collector strip attached to the outer surface of an exterior wall. Manifolds at the ends of the channels provide an inlet and an outlet for the air channels. But, because each of the channels has a small cross sectional flow area, the energy losses due to friction are high in this system. These losses necessitate the use of a large air pump to push air through the system and reduce the net energy savings of the system. Additionally, the horizontal orientation of the channels requires that an air pump be used to move the air through the channels.
Even though work has been done in recent years with regard to using the energy provided by the sun to heat buildings, none of the systems so far developed has provided the ordinary homeowner with an inexpensive, relatively easy-to-install, efficient, and aesthetically acceptable means for using this solar energy to aid in heating his dwelling.
In many areas of the country building owners, particularly homeowners, cover the exterior of their buildings with aluminum siding. Aluminum siding has been used for many years to provide an inexpensive, longlasting, and low maintenance exterior surface for buildings. The technology for manufacturing and installing aluminum siding is well known.
Aluminum siding typically comprises eight or ten inch wide strips of aluminum mounted on the exterior of the building. The outer surfaces of the aluminum strips are either painted or coated with other color-giving materials such as polyvinyl chloride. Once installed, the aluminum siding gives the building a like-new appearance.
Frequently, rather than being mounted directly on the surface of the building wall, the aluminum siding strips are mounted on furring strips that have been firmly attached to the wall. When these furring strips are used, a space is formed between the wall of the building and the aluminum siding.