Hygrothermal simulation of cathedral ceiling roofs with ventilated roofing tiles

Abstract

PurposeThe surface temperature of the sub-roof beneath the ventilation layer and the tiles is one of the most important factors for the hygrothermal performance of pitched roofs. The air layer between tiles and sub-roof and the air exchange with the outdoor air influence the heat transfer and therefore affect the moisture level inside the roof construction. The paper aims to discuss these issues.Design/methodology/approachThis paper provides the results of a research project performed at Fraunhofer-Institute for Building Physics, based on field test results. The investigations analyze the thermal behavior of different vented and ventilated roof constructions.FindingsIt was found that for a detailed model with roof cladding and ventilated air layer normally too many parameters are unknown. For that reason a simplified approach was set up, especially to consider the radiation exchange between the tiles and the underlay as well as the effects of the ventilation.Originality/valueNow, effective surface transfer parameters can substitute both cladding and air layer in the simulation, while the approach still provides a high accordance with the measured values. The paper provides characteristic values for different roofing situations to simulate ventilated roofs by means of hygrothermal simulation in a simplified way.