Frequency domain regression method to predict thermal behavior of brick wall of existing buildings

Abstract

The prediction of the thermal behavior of the envelope of old buildings (built before 1948), subjected to various boundary conditions, is very useful for the implementation of an effective thermal renovation strategy. For this purpose, the present work aims at studying the transient thermal behavior of a brick wall and determinate the optimum insulation thickness by using a theoretical model based on the Frequency-Domain Regression (FDR) model. The brick wall of 34cm thick (main characteristics of Northern European old buildings) has been used in this work. The numerical results agree well with experimental results obtained on a specially developed experimental setup. Subsequently, the model has been used to investigate the effects of the insulation thickness on the energy requirement and total cost.Simulation results indicated that thermal insulation is able to enhance the thermal behavior of massive wall, and that insulation thickness has influence on the profile of heat flux. The optimum insulation thicknesses for internal insulation vary between 5.5 and 12.4cm, vary between 4.9 and 8.4cm for external insulation depending on the fuel types.