Solar Air Niche Applications Reported in Task 19 Case Studies

One of the groups which Task 19 has set out to serve is industry, namely the manufacturers of components used in solar air systems. By publicizing successful solar air heating applications to encourage replication, and by publicizing industry's products, Task participants hope to give an important boost to that industry.

After a severe decline in the number of solar air collector manufacturers in the 1980's, a small renaissance has occurred in the 1990's. In Europe, at least a half dozen firms, two of which have been participating in the Task, have series production of solar air collectors for specialized niche markets. Two examples of these niches applications, representing two extremes, are vacation cottages and buildings with large volume spaces.

In the case of vacation cottages, collectors fulfill the function of passively maintaining an acceptable minimum temperature in such dwellings when they are unoccupied, thereby avoiding possible damage from freezing water lines and shortening the heat-up time before occupancy. Such applications, because relatively low air temperatures are acceptable, achieve a high efficiency. The absence of other internal gains during unoccupied periods effectively prolongs the heating season. Both these factors combined result in attractive economics for this application area.

In the second case, the collectors are typically used for pre-heating ventilation air and/or heating water via an air-to-water heat exchanger. Because no water circulates through the collector and the heat exchanger is located within the conditioned building envelope, freezing problems, with which water systems normally must cope, are avoided. When such systems serve two functions, namely ventilation pre-heat and water heating, the economics are improved in comparison to systems used only for ventilation pre-heating which then sit idle throughout the summer months. Because such systems entail a large number of collectors, the price per collector can be lower, further improving the economics. A primary example of such an application is a sports hall. Task 19 is documenting three such case studies in Norway and Germany.

In discussions with collector manufacturers, they expressed their desire to increase awareness by designers that manufactured collectors in fact exist. Too often, collectors and other components are invented by designers, and the custom systems are then site-built. The resulting systems usually do not achieve state-of-the art performance, are unnecessarily prone to durability problems, and tend to be considerably more expensive. To increase designer awareness of what is already available "off-the-shelf," Task 19 is producing a catalog of manufactured components for solar air systems. It will include criteria to consider in specifying a component as well as a directory of manufacturers.

Caption:
Apartment Building "Bo 90" in Copenhagen using solar air heating collectors.