Thermal performance of retrofitted envelopes with internal insulation - A comparative analysis

The paper discusses two main points; first is the validity of steady state analysis in assessing buildings’ heating and cooling loads, as well as the internal air and surface temperatures (TAIR, TSI) using UNI TS 11300-1:2008 compared to TRNSYS dynamic simulation software. The second aim is to understand how internal insulation affects the building envelope thermal inertia. Insulation is important to conserve heat in the heating season; however, it may contribute to space overheating in the summer. Thermal capacity is important in increasing human comfort in the space, limiting overheating in summer and managing peak temperatures due to internal or solar gains. Inside insulation can alter the dynamic behaviour of the existing envelope, and the aim is to understand the consequences of this intervention. The work presents an analysis of different internal envelope retrofitting solution, and deal with the climate of Milan and Palermo cities in Italy. The results show that steady state analysis for the heating and cooling loads calculation in cold climates is sufficient, while in hot climates, dynamic simulation is of major importance. They also discuss the importance of the thermal capacity and thickness of the finishing layers in moderating TAIR and TSI.