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.

In the current context of the transition toward climate neutrality and the pressing need to reduce energy consumption in the construction sector, nZEBs have become a central benchmark in European sustainability policies. These buildings offer multiple benefits, such as reduced operational costs, enhanced thermal comfort, and improved indoor air quality. Achieving such performance requires the integration of advanced technological solutions, including passive façades with ventilated cavities. The primary objective of this study is to investigate the influence of cavity geometry on the thermal behavior of a passive façade, through numerical simulations conducted in ANSYS Fluent 17. The study focuses on comparing five distinct configurations with varying cavity widths, aiming to identify the optimal solution in terms of heat transfer efficiency. The main contribution lies in the analysis and correlation of air temperature and velocity distributions with the cavity’s geometric parameters, highlighting the impact of channel width on thermal performance. The configuration with a 12 cm wide air channel recorded the highest heat flux at the outlet, approximately 44 times greater than the façade with a 4 cm wide channel, making it the most efficient solution. The results indicate significantly higher thermal efficiency for the configuration with a larger cavity width, contrary to initial intuitive assumptions. These insights provide a valuable framework for the optimal design of passive façades in nZEB applications and highlight the need for further research, combining numerical and experimental approaches, to develop sustainable and energy-efficient building envelope solutions.

As conventional fossil fuel systems release toxicants into the atmosphere, humanity is increasingly moving towards sustainability, towards using products that do not cause negative effects on the environment, have a long service life and offer multiple benefits. Solar air heating systems are increasingly used in household applications, even in industrial ones at times. The principle of operation of systems of this type is established on the existence of solar radiance, without this the panels have little or no efficiency at all, so they are limited to sunny periods. One of the methods of increasing the impact and performance of these systems is the realization of hybrid systems that offer several benefits with regard to heating the air in rooms, heating water and ventilating spaces. The meaning of this article is to present a summary of the existing literature, in the sphere of solar hybrid air heating systems, on the methods of improvement and the performance achieved.

This paper presents a low speed drive system with a simple and reliable construction, which can be used in an area where there is no power supply (isolated areas, forests, agricultural fields, etc.) and which operates on the basis of two heat sources, one from solar radiation and one provided by water. Alternatively, this system can be used to recover energy from wastewater from industry. The operation and role of the parameters that can influence the value of the rotation speed of the drive system are analyzed through a simulation, maintaining a constant speed in the case of the prototype is achieved through the control system because in real situations the temperature of heat sources can vary within certain limits. The models and tests performed highlight the parameters of the analyzed drive system and the limits of the range in which its speed can vary.

The paper presents elements regarding the production and testing of a Nitinol-operated micropump. Nitinol is used to build actuating and control systems due to its properties to change its shape under the action of temperature, the more so as it is used in form of springs developing traction force. Finally, the main performance of the micropump developed is presented. Depending on the current chosen for the power supply of Nitinol springs, the system pumps a certain amount of liquid in a certain time. The higher the current, the higher the speed reaction in pumping the liquid, however, it also takes longer time between pumping cycles to cool the springs, so they can revert their direction of movement. For optimal operation, we have to go on an average current of supply of springs, the amount of liquid is average and the cooling time of the springs will still be average.