The 'Solar Slab' consists of cement blocks placed so that their holes line up, and then these blocks are covered with a concrete slab. Vents in the south and north sides of the house floors are integrated with the holes in the concrete blocks. Air heated by south-facing windows rises and is circulated throughout the house cooler air is drawn through the cement blocks under the slab by natural ventilation pressure. In order to prevent moisture from entering the cement block heat storage system, careful attention must be paid to the foundation design.

The concrete slab is a form of structural mass which, in its self will store heat. The under floor ducting facilitates air flow and reduces the effect of hot spots or over heating. (See Glazing section). This passive system should, in theory, work on its own. However the nature of its ducting allows easy integration with conventional HVAC equipment, and so fans may be used to increase air flow further reducing the chance of overheating.

Finally a back-up heat-pump can be used to pump either warm or cooled air into the house should the passive system fail to meet the temperatures required for human comfort. The most likely time for passive failure would be on very cold winter mornings. If sufficient heat has not been stored the previous day, and/or the over night heat loss is high due to extremely low outside temperatures, then a heat pump would be used to push hot air under the slab warming it and effectively creating an under floor radiant heat system.