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Actively collect and convert solar radiation into heat or electrical energy for building use.

There are two basic systems: liquid and air, each based on the type of fluid heated in the collectors. Liquid systems use water or an antifreeze solution to capture, transfer and store heat produced by “hydronic” collectors. Air systems use air to capture, transfer, store and distribute heat from the “air” collectors. Liquid systems use flat-plate collectors or evacuated-tube solar collectors, similar to solar hot water collectors. The liquid flows to either a storage tank or a heat exchanger for immediate use. Air systems often use collectors integrated into the wall or roof to hide their appearance. (Source:

Evaluate water-based collectors. A water-based system typically uses heat exchangers to move heat from the collection medium to the heat-storage or distribution medium. Heat exchangers can transfer heat to water-storage, water-distribution, and also air-distribution systems. Consider air-based collectors. Air-based systems are the least complex of active systems and, unlike liquid systems, do not freeze; however they are less efficient. (Source:

The relative cost of active solar heating systems varies and decreases with system size. Systems usually cost $30 to $80 per square foot of collector area, installed. The economics of an active space heating system can be improved if space heating is combined with water heating. A dual-purpose system is usually more cost-effective because an otherwise idle collector can heat water in the summer. (Source:

Active solar heating provides free energy efficiently and offers long-term benefits including reduced utility bills and operational costs. Building operations will also be cushioned from future fuel shortages and price increases.

Determine heat storage needs. Heating requirements in commercial buildings are greatest in the early morning and evening, when solar heat is not available. These buildings require a thermal-storage system to provide solar heat on an as-needed basis after it has been collected.

1.6.2 Photovoltaics
1.4.8 Solar Hot Water Collectors
1.5.3 Commissioning
1.7.3 Solar Cooling
1.7.5 Fabric Energy Storage