The European Union set ambitious targets to achieve climate neutrality by 2050, and one of the measures taken towards this goal was the implementation of nearly Zero-Energy Buildings. Despite the commitments of the EU member states, many householders and investors had a disposition to incredulity regarding the energy efficiency of the buildings due to the higher cost of the investment and the relatively long payback time. However, at the end of 2021, the energy crisis significantly rewrote the circumstances, and energy prices and the costs of construction materials began to rise. In this situation, it was necessary to reconsider the importance of energy efficiency for buildings due to the maintenance costs. This article aims to assess changes in payback periods over the past 13 years and conduct life cycle cost evaluations by comparing energy-efficient residential buildings with traditional houses. The analysis considers variations in construction materials and labor costs in Romania, as well as energy price changes during the building’s operational phase. Through these methodologies, it has been demonstrated that the implementation of energy-efficient buildings offers a cost-effective solution already in the medium term, providing incentives for investors and future houseowners to reduce their dependence on energy and pursue long-term decarbonization.

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Energy-efficient buildings have received increasing attention in recent times as they represent a direction that promotes the objectives of a sustainable, competitive and decarbonized energy policy. In order to meet the minimum requirements of the nearly zero-energy buildings (nZEB) the thermal characteristics of the envelope play an important role. The aim of the paper is to present and analyse the thermal behaviour of complex joints for an energy efficient school building, for which the formation of thermal bridges has been reduced by applying improved geometrical and technological solutions. Since most of the thermal bridge catalogues did not provide updated details for the studied joints, numerical calculations, as two-dimensional finite elements thermal simulations, were performed to determine thermal transmittance coefficients and the U-value..