A Literature Review on the European Legislative Framework for Energy Efficiency, Nearly Zero-Energy Buildings (nZEB), and the Promotion of Renewable Electricity Generation

Improving the energy efficiency of buildings is a major priority within the context of the European objectives to reduce greenhouse gas emissions by 55% by 2030 and to achieve climate neutrality by 2050. Nearly Zero-Energy Buildings (nZEBs) offer a promising solution to significantly reduce energy consumption and promote the use of renewable energy sources. There is a significant gap in the scholarly literature regarding systematic reviews focused on the advancements in European legislation related to energy efficiency. Consequently, this paper aims to provide a comprehensive synthesis of the key legislative norms targeting the energy efficiency of buildings and the necessity of utilizing renewable energy sources for electricity generation, with a particular focus on the forecasts for the year 2030. The objective is to offer valuable reference resources and to support the global expansion of nZEB implementation in a sustainable and resilient manner. This research thoroughly evaluates the development of nZEBs, emphasizing design concepts, technological innovations, and their impact on energy efficiency. An analysis of the main barriers to implementation highlights high costs, limited technological feasibility, regulatory constraints, and insufficient stakeholder engagement. The purpose of this paper is to review the literature on building energy efficiency and the European trajectory from passive to zero-energy buildings.