![]() Currently, the thermal inertia evaluation is done using numerical methods and several authors evaluated the influence of the walls thermal properties on the building energy performance, by comparing different construction systems. The theoretical approach to this problem is related to the inertial properties of a wall, an issue that dates back to the classical work by Fourier dealing with transient heat conduction in a system, modeled by a semi-infinite wall-consisting of a homogeneous, isotropic medium-to which a sinusoidal temperature fluctuation is applied. Buildings’ massive walls store heat when the heating plant is working and, during the summer, they contribute to the phase shift of the external thermal waves. Regarding building envelope, the first intervention is related to the thermal transmittance value reduction but it is important to emphasize the building energy savings that could be achieved by exploiting thermal inertia. In fact, through the Directive 2002/91/CE the European Community highlighted how the increase of energy efficiency is a point of strength within the set of measures and actions necessary to comply with the Kyoto Protocol. Improving thermal performance of buildings is the first step to reduce annual energy demand and, consequently, air pollution. Finally, the comparison between Test-Cell’s annual energy demands, performed by using a commercial code based on the Italian standard UNITS 11300 and the dynamic code, TRNSYS, was carried out. Moreover, the attenuation between external surface temperatures and internal ones during summer (July) was calculated. Through TRNSYS, it was possible to define maximum surface temperatures and to calculate thermal lag between maximum values, both external and internal. Different stratigraphies, characterized by the same thermal transmittance value, composed by massive elements and insulating layers in different order, were simulated. In order to understand the inertial behavior of walls, a cubic Test-Cell was modelled through the dynamic calculation code TRNSYS and three different wall types were tested. These standards require an energy analysis under steady-state condition, underestimating the thermal inertia of the building. ![]() ![]() ![]() Considering Italian standards, these analyses are based on the UNI TS 11300 that defines the procedures for the national implementation of the UNI EN ISO 13790. Nowadays, it is possible to use energy analysis software to simulate the building energy performance. This study aims to highlight the importance of thermal inertia in buildings. ![]()
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