Most definitions and discussions of solar heating and cooling are restricted to system designs that use manufactured hardware and components that are either off-the-shelf (e.g., pumps, fans, heat exchangers) or can quickly be mass produced, marketed, and serviced (e.g., collectors, fluids, controls). “Solar systems” are usually assumed to require an assemblage of components that includes collectors, thermal storage, a thermal energy transport system between the collector array and storage, and another between storage and the heated or cooled building. Both transport systems are assumed to use pumps or fans. Further, the components usually are attached to or installed in a building without having much effect on the building’s architectural fabric (roof, walls, floor, etc.). Such systems are often referred to as “active.”