Thermo-Physical Performance and Energy Aspects of Vertical Walls Opaque to the Retrofitting Of Buildings through a Simulation under Non-Stationary

The building envelope of a building constructed in the past usually presents design characteristics which are not suitable to avoid the thermal exchanges between inside and outside. The previous use of inefficient building systems, often directed to saving of materials, has created inadequate walls to energy saving. Opaque components of reduced thickness and often in a single layer, except for the plaster with low thermal insulation characteristics, have high thermal transmittance values. This is a characteristic parameter for evaluating energy in steady and winter state, as well as inadequate values of phase shift of the heat wave, characteristic parameter of the behavior under dynamic and summer state. In this work we report a summary of a comparative study of thermal characteristics, in steady and unsteady state, of the external opaque vertical surfaces exposed to energy retrofitting with different techniques. The horizontal walls, the perimeter walls of closure or the horizontal and inclined surfaces, such as roofs, largely influence the energy efficiency and the resulting performance of a building. We started our study considering the energy performance of a generic 200 mm calcareous tuff wall, commonly used in old buildings in Southern Italy. We varied the thickness, by simulating the behavior, through retrofitting techniques such as exterior insulation and finishing system, the insertion of a ventilated cavity or interstitial insulation, or an internal insulation.