Dynamics of Heat Accumulation by Building Envelopes

Abstract

This study proposes a method for studying heat flows inside building envelopes based on the theory of nonstationary heat conduction with periodic fluctuations in air temperature. The process of energy accumulation, heat input (heat inflow), and heat loss (heat outflow) through building envelopes is studied as a periodic process. The results of calculating the daily dynamics of heat flows through flat walls are given. The time dependence of integral temperature \({{T}_{{{\text{int}}}}}\) of flat wall averaged over volume, which determines accumulated heat \({{W}_{{{\text{accum}}}}}\) in the wall material at any given time of day or for a given time interval, is obtained. It is shown that the change in the \({{T}_{{{\text{int}}}}}\) value for stationary conditions is 0.5°C when the outside air temperature changes by 1°C. For a periodic heat transfer process, the change in amplitude A_int of fluctuations of the average integral wall temperature is 0.2°C when amplitude A_outs of fluctuations in the outside air temperature changes by 1°C. The daily and seasonal dynamics of \({{T}_{{{\text{int}}}}}\) and \({{W}_{{{\text{accum}}}}}\) are determined for the climatic conditions of Central Asia.