The Cost-Optimal Optimization of public buildings in cold and warm climates: two case-studies in Germany and Italy

Directive EU 844/2018, in the matter of energy performance of buildings and future goals of energy efficiency for the EU Member Countries, extends the standard of nearly zero-energy building goals to the existing building stock, with the mandatory aim of almost complete decarbonization of the whole sector within 2050, and thus a strong reduction of greenhouse gas pollution of about 80-95% compared to the levels of '90s. In this frame, the present study purposes the multi-objective optimizations of two office buildings, located in Berlin (Germany, European backcountry, "Cfb" climate in the classification of Köppen and Geiger) and Naples (Italy, Mediterranean coast, "Csa" climate classification), with the aim of finding the best trade-off between two couples of contrasting targets, representative of private and public interests, respectively: minimization of indoor thermal discomfort and operational costs, and minimization of indoor thermal discomfort and environmental impact. In addition, an investment cost analysis is performed by optimizing operational costs and total construction costs. The explored and investigated energy conservation measures, to apply during the building retrofit, involve the main levers of energy efficiency, and thus the building envelope, and the active energy systems. The results underline that the cost-optimal energy measures to apply during the building refurbishments deeply differ based on the building usage, the intensity of required indoor comfort, and depending on the climatic peculiarities and building construction technologies.