In order to define accelerated ageing cycles useful to evaluate reference service life is very important to analyse the “reference” climatic conditions to be simulated. In this paper we will report the activities developed by Durability of Building Components Group of Politecnico di Milano to set up the accelerated ageing cycle for ETICS, based on a national agreement within the Italian Network of Durability Evaluation laboratories. Statistical climatic data as Test Reference Year and standardized data have been considered to determine the most severe climatic conditions relevant for ETICS durability aspects. The considered agents have been selected taking into account the degradation and failure modes for the specific ETICS component. The most severe thermal shock events in summer and winter conditions have been analysed to define the temperatures during sub-cycles. Rain ,freeze and UV conditions have been defined taking into account their statistical occurrence and the ratio between summer and winter cycling have been defined on the base of statistical probability of such events. This analysis allowed to obtain lab ageing cycles calculated on the base of statistical data for the considered Reference climatic and geographical conditions. This will be useful to compare results based on lab accelerated ageing and outdoor exposure results.