The aerodynamics of roofs comprising layers of variable permeabilities

This project will entail computational fluid dynamics, careful measurements and detailed analyses to build on limited existing research(1) and generate design information to fill prevailing gaps in knowledge. It will thus span the full spectrum of research, from fundamental studies to the development of design information for implementation in recognised design standards, specifically British Standards(2,3) and related European Standards. It has direct industrial relevance to domestic housing, and there will be industrial involvement in the project.
It will study the flow of air through zones bounded by layers of varying air permeabilities, driven by external fluctuating wind pressures. The zones are those that comprise a conventional house roof: the rooms, the loft, and the batten-space; the layers are the ceiling, the underlay, and the tiles or slates. The questions to be addressed are the magnitudes of the loads on the different layers, and the effective ventilation of each zone (to combat condensation formation). The driving mechanisms are the external wind, and thermal buoyancy (when wind is negligible). Wind pressures vary according to wind speeds, roof geometry, and site location. They vary spatially across the roof, and temporally.
The research is intended to identify the share of wind load across the ceiling, the underlay and the roof tiles, according to the relevant physical parameters applying to each layer and according to the constructional details, and to indentify the risks of condensation formation in the loft space and batten-space, again according to the relevant parameters.