This is the most powerful of the Radiantec heating systems. It is a hybrid system that combines the best features of active and passive technologies while leaving behind their respective disadvantages.

A significant advantage of the Solar Option I system is that it is capable of meeting nearly all of a residential type building’s heating needs, even in quite challenging climates. Another advantage is exceptionally high efficiency that very low operating temperatures entail. “Substantial improvements were noted in system efficiency, overall performance, initial cost and architectural flexibility. An increase in collector efficiency translates into fewer solar panels, lowered costs,and easier design integration into accepted building styles. A large thermal mass, integrated within the building’s structure provides prolonged solar storage, radiant comfort and further lowered costs.”

-Report to US Department of Energy
1983 (DOE/CE15140-T)

A very large thermal storage area is created with slab on grade construction. The storage area consists of the slab itself and up to two feet of compacted sand or gravel. The storage detail can have very little or no additional cost depending upon insulation. Despite reports to the contrary, there are no annualizing benefits, or storage that carries over from season to season.

The very large thermal storage area, when coupled to solar collectors produces high solar collector efficiency, a potential for high solar heating fractions, reasonable first cost and very good cost benefits, all within a startling simple design.

Installation in a joisted floor is a snap in new construction and is also an easy retrofit in an existing home if you have access to your floor joists from below. The wooden floor system won’t store as much energy as a slab system, but it can still store significant heat and will result in a very comfortable and warm floor.

The solar domestic water heater is itself an attractive option. It is not always convenient to provide the very large heat storage mass that is used with the Solar Option One. Also, it is not always possible to install a large number of solar panels. In such cases, a domestic hot water heater with a supplemental heating potential can have value. When a less aggressive storage mass is used, such as a topping slab over plywood, or ceramic floor tiles or even a regular wood floor system, the floor system can still provide appreciable benefit.

There is abundant domestic hot water when the building is occupied, and when unoccupied, the solar keeps the building at a minimal temperature with minimal cost. The floor and building itself can function as solar storage because a wide range of temperatures is acceptable (i.e. 45-85 degrees F).