The Influence of Natural and Forced Convection in Attics – A CFD Analysis

Abstract

In this thesis project, the air and heat flow in a principal insulated cold attic model has been numerically investigated through the use of the commercial CFD software ANSYS Fluent. A numerical model for the heat transfer has been developed and verified with experiments on a simple box model containing insulation and an overlying horizontal air cavity. This numerical model was then applied on a cold attic model with insulation and wooden joists. Both situations with pure natural convection, caused by the temperature difference between the hot floor of the attic and the cold roof, as well as situations where the attic in addition was exposed to forced convection in the form of attic ventilation has been investigated. This project has been a collaboration between ÅF Industry AB and the Division of Building Technology at Chalmers University of Technology.