Experimental results on the thermal properties of reflective materials for building insulation applications

Double-skin systems represent a viable and efficient solution for building refurbishment, producing a noticeable reduction of the thermal losses through the envelope. In order to limit the external encumbrance, the total system thickness have to be contained, however precise values of the thermal transmittance should be achieved. For instance, in the Italian regulation context, requalification interventions by double-skin systems are not classified as a building volumetric growth if the thermal transmittance of the new envelope configuration is lower than a limit value, further decreased of 10%. A less invasive system could be attained by thermo-reflective panels located inside the air-gap formed between the existing wall and the double-skin. Indeed, these materials lead to a noticeable reduction of the radiative thermal losses allowing to use external insulated panels more thin. In this paper, experimental tests carried out on a sample with different types of reflective materials have shown that air-gap thermal resistance can be increased also 9 times than a conventional air-gap. The tests have shown that the radiative thermal exchange contribute is strongly reduced, as well as the convective one. Moreover, these advantages are more evident in presence of limited temperature differences between the wrapping surfaces. In the better case, the application of thermo-reflective materials could produce an insulation thickness reduction in the double-skin system of about 5 cm.