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• Aging problem for a wall package with vacuum insulation panels is studied. • Measures of heat flux and temperatures for 5 years are compared. • Experimental and analytical elaborations are combined for finding the aging trend. • The aging curve is implemented in a case study by means of dynamic simulation tool. • Energy consumptions, environmental indices and cost savings are discussed. The lack of data on the aging rate, under real operating conditions, is one of the most critical aspects for the diffusion of vacuum insulation panels in the building sector. This problem is analyzed in this paper by means of an integrated experimental-numerical approach. The panels under investigation are characterized by micro-porous silica pressed powder core with an aluminum barrier layer, for a total thickness of 10 mm. These are the insulation layer of a wall made of autoclaved aerated concrete blocks (total thickness of 21 cm) placed in a test room located in Benevento (south Italy). The experimental analysis is focused on the monitoring of heat flux and temperatures in order to evaluate the performance by means of the comparison with the same wall without insulation and for the indirect determination of the aging after five years (2015–2020). Results indicate an increment of thermal conductivity of 10.6%. Moreover, basing on experimental data, a semi-empirical linear function is appropriate to approximate the aging trend. A numerical case study, that implement the obtained aging trend, shows that the increment of thermal conductivity of vacuum insulation panels brings a reduction of the expected energy saving of 3% after 15 years. This result is true for several European cities with heating dominated climates. [ABSTRACT FROM AUTHOR]