The debate on the presence of economic benefits in the European Union (EU) is not over. The study responds unequivocally to this question, with the intensity of economic development in the countries that joined the European Union in 2004 and beyond twice as high as that of the countries that joined it this year, i.e. the EU’s old ones compared to the new ones; smoothness – 1.1 times and dynamics – 1.6 times. Another important trend for further development is that, as the level of economic development increases, its smoothness is diminishing. In respect of the context of the EP of all EU Members, it turned out that the higher intensity of enlargement was characterised by higher economic levels, with similar homogeneity and almost identical values for the dynamic indicator. The introduction to the article presents the context of the studies, i.e. two groups of EU Community countries are formed according to their level of economic development and the year of their accession to the Community, as well as a survey scheme. The literature review reveals the methods used to analyse the convergence of economic development in these countries, as members of the Community. The research methodology introduces the indicator of economic development of countries and provides a methodology for assessing its dynamics. The empirical part assesses the dynamics of economic development of both groups of countries and identifies trends in terms of convergence. The discussion section summarises the consolidation and destabilising factors in the EU and the importance of the study carried out in this context. The conclusions present the main results of the studies and outline their further directions. The results of the study can be used both in the EU and for the purpose-oriented decisions of its members on further economic development.

The indoor environment that surrounds us and the elements in it affect not only our mood but also the air quality. Vegetation elements are currently more popular, especially for their aesthetic value but also because of the fact that they affect the physical parameters of the indoor environment such as temperature and humidity. Water elements are a similar example. The presented paper combines these two elements to achieve the best possible level of thermal comfort. Experimental verification of the influence of the living wall on air temperature and humidity took place during the heating season in the city of Brno in the space of the university, while three scenarios were created: the effect of the living wall in a semi-open space, an enclosed space, and a space with a water wall with regulated water temperature. The potential of the water wall is determined based on experimental verification in laboratory conditions. The results show that the synergy of the living and water wall in the indoor space may eliminate the risk of too-low humidity during the heating season.

The article presents current research results in the field of airflow through a façade with a width of 1 m and a height of 13.7 m and with a ventilated gap, and its effect on the year-round heat balance of this façade. An idea to influence airflow in the ventilated gap of the façade is presented based on the results of developed software and the suitability of closing the air gap in winter and in the transition period of the year is described. First, the boundary conditions of the calculations, which are further used in the energy balance between the interior of the building and the exterior environment are defined. In order to include these influences, a discrete analytical calculation was created. It consists of the time distribution of the investigated thermal phenomena calculations. A significant finding is an obvious benefit of controlling the airflow through a ventilated gap in the winter and especially in the transitional period of the year. This technological knowledge has a high potential for energy savings related to the heating of buildings. As the calculations show, airflow control through a ventilated façade reduces heat flow by 25–30% on average, and in contrast, it increases heat gains by 20% and the specific values are presented within the article.

This case study presents a comparative analysis of real-world operation of two residential domestic hot water (DHW) preparation methods both connected to their own air-to-water heat pump (HP) located in Central Europe. One system employs a conventional configuration with separate tanks and an internal heating coil (HP-B), while the other features a compact tank-in-tank setup where DHW is heated via an integrated buffer tank (HP-A). Both systems were monitored under real operational conditions, with seasonal and annual coefficients of performance (COP, SCOP) calculated to evaluate efficiency. In the absence of complete thermal output data for one system, a reconstruction method based on the other’s performance and known heat losses was applied. The findings confirm that DHW system design significantly affects seasonal efficiency, particularly during summer operation when heating DHW dominates the energy load. The energy cost savings on heating during summer months could reach 44%. The tank-in-tank system showed higher electrical consumption and lower SCOP due to internal heat transfer dynamics and dual-function operation. The study further shows associated energy and cost differences and demonstrates a practical approach to comparing real-world systems offering insights for design optimisation and operational strategy. The authors of the article used the results of their research and experience from implementations as very effective feedback for further research and development. The novelty and uniqueness of the article lie in the energy comparison of two different connections of the hot water and heating water storage tanks with heat source systems using an “air-to-water” heat pump. The benefit of the solution in question is evident from the technical and economic evaluation.