A new parameter for the dynamic analysis of building walls using the harmonic method

The authors propose a methodology to schematize correctly the capacitive effects in the transmission of heat in the multilayered walls of buildings. An analytical study is presented related to a steady periodic regime allowing consideration of three external loads acting singularly or simultaneously: air temperature, apparent sky temperature and incident solar irradiation. Such a study is applied in the case of four traditional types of wall (A - brick wall, B - hollow wall, C - polarized brick wall, D - prefabricated wall). The expression of the oscillating heat flux, which penetrates the internal environment, and the conductive heat flux which penetrates the wall in contact with the external air, was obtained by means of the electrical analogy and the resolution of the equivalent circuit. It is demonstrated that the nondimensional periodic global transmittance, the ratio between the heat flux which is transferred to the indoor environment and the external heat flux, with the plant turned on, is the most suitable nondimensional parameter for the dynamic analysis of the walls. This parameter allows for the evaluation of all the typical dynamic quantities for the complete description of the thermal behavior of the walls.