Optimizing insulation-thermal mass wall layer distribution from maximum time lag and minimum decrement factor point of view

Different wall construction configurations lead to different wall thermal behaviour which affects energy consumption and thermal comfort of the room. In this study, the thermal time constant, the time lag, and the decrement factor are calculated for different wall configurations in order to investigate the best insulation/thermal mass layer distribution in external walls. First, this is done for just a wall by developing a numerical model to solve the one dimensional heat transfer equation in a multilayered wall subjected to convective boundary conditions. Second, this is done for a full-scale house using the whole building energy simulation program EnergyPlus. Also, the performance of traditional insulation is compared to that of a newly developed insulating coating, based on super-insulating silica aerogels, from maximum time lag and minimum decrement factor point of view. Results showed that placing a layer of insulation at the middle of the wall and another one at the outer wall surface or using a five layered wall: 1- three layers of insulation placed at the inside, middle, and outside and 2- three layers of thermal mass separated by two layers of insulation are the best configurations. Also, the insulating coating showed a better performance with an increase in time lag of about 1 hour and decrease in decrement factor of about 5%.