Practical solution for ventilated ground slabs and roof slabs

Abstract

Ventilated ground slabs are effective in improving the thermal behaviour and damp protection of buildings. The potential for passive cooling of roof slabs incorporating an air cavity is also important with respect to thermal comfort. The introduction of an air cavity system is inspired from historic and traditional buildings. Ground slabs in historic buildings in Malta were constructed and detailed in order to allow for a damp proofing devise. Roof systems in traditional buildings incorporated a ventilated roof or an air cavity. The concept has been proposed again in contemporary buildings with a raised concrete slab, using a modular formwork system, made out of lightweight recycled polypropylene. The system is primarily intended for load-bearing floors to allow for the passage of services and damp proofing. The system is also used in the construction of roof slabs, where the cast in situ concrete slab is isolated from the screed with the introduction of a ventilated air space, to curtail the conduction and inward radiation of heat from the intense solar insolation on the concrete roof. The air cavity in roof structures is not ventilated during the cold season. The system is easily assembled at minimal additional work, and presents an innovative way of reducing heat transfer in roofs, and potentially reducing the overall cooling load.