The relation between nZEB requirements, local climate, and building features. the nZEB model application to two sample buildings, in different climatic conditions

In 2016, the European Commission (EC) published the Recommendation 2016/1318 on guidelines for the promotion of nearly zero-energy buildings (nZEBs) and best practices to ensure that, by 2020, all new buildings are nZEBs. In relation to the EC document, the study examines the applicability of the design of nZEBs in various climatic conditions, evaluating possible global scenarios for the renovation of the existing residential buildings. The analysis is applied to two building types, a single-family house and an apartment block located in different climatic zones, through the reference notional building (RNB). The requirement for the building under design is represented by the energy performance of the RNB. This one is outlined at national level, by local legislation, aiming at the nZEB target. Therefore, in the present investigation, the RNB is used to calculate the energy performance indexes, depending on different climatic conditions, chosen to be representative of various Heating Degree Days ranges. The results are intended to demonstrate that there is not a unique nZEB level, but the reference strongly depends on the local conditions and the building features. As the framework definition of nZEB in the EPBD and in the national legislation does not differentiate between new and existing buildings, the results of the study can be used as baseline energy performance for the quantification of energy and environmental savings, and to guide buildings refurbishment policies