The calculus of the thermal equivalent conductivity of the ecological roof

Abstract

Through the monitoring of an ecological roof located on the building of the Escuela Técnica Superior de Ingenieros Agrónomos (ETSIA) of the Universidad Politécnica de Madrid (UPM), the thermal equivalent conductivity has been determined. An equation that establishes a relationship among the energetic balance of a vegetable coverage in a natural environment, and the energetic balance of an ecological cover on a roof has been formulated. Three important factors have been taken into account: the quantities of absorbed, reflected, transmitted, evapotranpirated and used in the photosynthesis process solar radiation; the convective heat flow within the vegetable layer; and the conductivity heat flow. Through this process, an equation for the calculus of the thermal equivalent conductivity of the ecological roof was obtained. The result (0,12 W/m ºC) was evaluated and compared with those obtained through the essay of a sample of the same parcel carried out in the materials laboratory of the Ministerio de Fomento de España.