The full‑scale invasion of Ukraine has caused extensive physical destruction and long‑term disruption to cities, infrastructure, and everyday life across the country. Although the conflict is ongoing, planning for post‑war recovery requires an early understanding of both the spatial extent of damage and the priorities of affected communities. This article examines war‑related damages and post‑war reconstruction requirements as identified by Ukrainian citizens through a nationwide online survey conducted between May and July 2024. A total of 420 respondents reported varying levels of destruction across regions, with the most severe impacts concentrated in the north, east, and south of the country. When asked to prioritise reconstruction needs, the recovery of energy infrastructure emerged as the most important area of intervention, followed by humanitarian demining and housing.

In the article there are presented the results of experimental determination of the long range of the swirled air flows from two air distributors with 6 and 12 plates respectively. As a result of the research, nomograms of the dependence of the long range of the swirled air jet on its initial velocity and the angle of inclination of the rotary plates for both air distributors were constructed. The obtained nomograms were approximated by empirical formulas. The purpose of the research was to study the long range of swirled air streams depending on their initial velocity and the angle of inclination of the rotary plates of the proposed two air distributors, to construct graphic nomograms and to obtain empirical calculation formulas for the different initial conditions in the premise. The swirled air stream creates sufficient attenuation of the supply air flow velocity.

This study investigates the enhancement of building energy efficiency through the integration of hybrid photovoltaic-thermal (PVT) solar collectors into the facade structures of monolithic-frame buildings. An improved design for a hybrid solar collector is proposed, which simultaneously functions as a translucent building envelope (window) and a source of both thermal and electrical energy. An experimental test rig was developed to investigate the influence of solar radiation intensity (300–900 W/m2), the angle of incidence (30–90°), and the specific coolant flow rate on the thermal performance and efficiency of a solar thermal supply system with integrated thermal energy storage. A mathematical Design of Experiments (DoE) methodology was applied, ensuring the statistical reliability of the results while minimizing the required number of trials. Experimental data established that maximum efficiency values (up to 41

This manuscript presents the experimental results of a study on a long range of the flat air streams created by a linear louvered diffuser. During the study, graphs of dependence of a long-range of the flat air streams on their initial velocity and the number of slots of the linear louver diffuser have been constructed. The resulting graphs have been approximated by the empirical equations. The aim of the article is to research the long-range of the flat air streams depending on two determining factors: jet initial velocity and the number of slots of a linear louver diffuser; to design the corresponding graphs and to determine empirical formulas for different conditions of the air distribution in a room. Linear louver diffuser creates adequate attenuation of the flat tidal air streams and sufficient their long-range. The long-range of the resulting flat air jet increases with the increasing its initial velocity and the decreasing the number of the flat linear louvered diffuser slots.

The manuscript presents the results of a study of ways to intensify the heat transfer process from the coolant in the spiral heat exchanger to the water of an open reservoir. The purpose of this manuscript is to study the process of water cooling of a single cylindrical tube and a corridor bundle of tubes; determine the heat transfer coefficient depending on the tube diameter and velocity of the cooling water, taking into account the velocity profile diagram at a flow angle of 900. The influence of the cooling water velocity, pipe diameter, and the presence of a corridor bundle of pipes on the intensification of the heat transfer process was quantitatively investigated. Analytical equations were analyzed to ensure the intensification of the cooling process of a single cylindrical tube and a corridor bundle of tubes using a developed heat pump system protected by a patent of Ukraine. As a result of the study, heat transfer coefficients were determined under different initial conditions for intensification of the heat transfer process.

The Russian invasion of Ukraine has resulted in the large-scale destruction of many cities across the country. Although the war has not yet ended, there will come a time when the conflict concludes, and reconstruction efforts will begin. Global experiences show that the first step in preparing for post-war reconstruction is to assess the level of destruction. Additionally, it is essential to understand people’s needs and priorities. Otherwise, reconstruction activities may fail to address the existing challenges and actual needs of local communities. This study aims to explore post-war reconstruction priorities of Ukrainians, with special focus on the energy sector and particularly the district heating facilities. During hostilities, a significant part of Ukraine’s energy infrastructure was damaged or destroyed, which will be an essential sector in the recovery of other sectors. Research work involved undertaking an online survey with questions focusing on Ukrainians’ assessment of the importance of the reconstruction of the energy sector. A total of 420 people from different regions of Ukraine, different age groups and professional backgrounds participated in the survey. Results show that a significant number of Ukrainian citizens have a high level of energy awareness. Thus, when asked what measure of post-war reconstruction of the energy sector they consider of high importance, 64% of respondents chose the answer “Reconstruction using energy-saving construction technologies and energy-efficient engineering systems, even if it takes more time”. Furthermore, 32% of respondents are ready to pay more for district heating services if alternative energy sources are used to generate heat.

This manuscript examines indoor air distribution with a linear louvered diffuser. The purpose of this manuscript is to research a linear louvered diffuser to determine its technical characteristics. Theoretical and experimental studies were conducted to establish graphical and analytical dependencies for determining air jets aerodynamic characteristics. According to the results of the research, graphical dependencies and theoretical equations were obtained for determining the velocity fields of the air jet flowing from the linear louvered diffuser, and ways of improving air distribution in premises of various purposes were indicated. Diagrams were created to determine the relative velocity of the air jet depending on the current longitudinal and transverse coordinates under different initial conditions. The speed of the jet decreases with the growth of the longitudinal and transverse current coordinate and with the increase in the number of air outlet slots. The attenuation coefficient of the jet speed decreases with an increase in the number of air outlet slots.

The article investigates the improvement of air distribution efficiency in a room when using a linear diffuser as an air distribution device. Linear diffusers allow to provide comfortable conditions in the room. The paper analyzes some characteristics of the air flow formed when using linear diffusers. The influence of the geometric parameters of the diffuser on the quality of the microclimate is considered, in particular, such characteristics as jet boundaries and velocity profiles in the jet cross-sections are considered. Numerical modeling allowed to determine the optimal operating modes of such diffusers and evaluate their efficiency. Experimental studies confirmed that linear diffusers contribute to a more uniform distribution of supply air. The results obtained can be used to optimize and improve ventilation systems in buildings, which will contribute to increasing energy efficiency and reducing operating costs.

Geothermal ventilation is used for preheating outdoor air in the cold season and pre-cooling it in the warm season using a mechanical ventilation system. It allows the building to save on traditional fuels when preheating or cooling outdoor supplied air by using low-potential soil heat. Air and soil exchange heat through the walls of the ground heat exchanger. Ground heat exchangers for geothermal ventilation can be installed in the ground according to a ring scheme, a Tichelmann scheme, or with a coil scheme. This article focuses on the geothermal ventilation system of a residential building using two methods of installing ground heat exchangers. The thermal energy performance of ground heat exchangers when laid in a coil format and in the Tichelmann scheme was compared. The operation of the variants was simulated using REHAU-GAHE software. As the calculation results showed, the thermal energy performance of the system for the two types of installation is approximately the same, since the program is set to maintain the minimum temperature at the outlet of the ground heat exchanger. For example, the amount of heat received per year for a ground heat exchanger installed in a coil format is 7310.22 kWh/year, and for a ground heat exchanger installed according to the Tichelmann scheme – 7430.35 kWh/year. As for the geometric dimensions, the results obtained are significantly different. Thus, for an installation depth of 2.5 m when installed in a coil format, the pipeline diameter was 500 mm and the length was 168 m, and when installed according to the Tichelmann scheme – the diameter was 250 mm and the length was 403 m.

District heating systems are the basis of the future sustainable energy system of the country. Reducing heat losses from heating networks is one of the main ways to ensure the economic and sustainable functioning of heating systems. The greatest effect for reducing heat losses is characterized by heating networks that combine the use of thermal insulation of pipelines with the use of a low-temperature coolant. This paper considers a two-pipe water system of district heating, the heat network of which is laid in impassable channels, and steel pipelines are pre-insulated with polyurethane foam. As studies of this system have shown, reducing the temperature of the coolant in the supply pipeline from 95 °C to 70 °C and in the return pipeline from 70 °C to 50 °C, i.e. the use of a low-temperature coolant, allows you to reduce heat losses from heating networks by 30

The article presents the study results of air distribution in a room with a flat air jet. In particular, dynamic pressure, density and viscosity of air flow were considered. Aim of a paper is to numerically simulate these physical properties of a flat air jet in a room. A graphical representation of air jet parameters was obtained using package CFD Ansys FLUENT software. A hypothesis of applying Mendeleev-Clapeyron equation to moving air flow was considered. Flat air jets have been found to be effective in terms of velocity attenuation in indoor air distribution. The dependence of the tidal flat compressed air stream velocity on time and longitudinal current coordinate simultaneously is graphically presented. Their proper long-range allows for comfortable microclimate conditions using a minimum number of them. Convergence of experimental studies results and numerical modeling confirms adequacy of a theory of the experiment.

In the current context of worsening environmental conditions and depletion of natural resources, there is an urgent need for the development and implementation of technologies that utilize renewable energy sources. Traditional sources pollute the environment and contribute to climate change, which makes the issue of eco-friendly technologies increasingly relevant. Therefore, one of the promising solutions to these challenges is the use of solar collectors, which convert solar radiation into electrical and thermal energy. Hybrid solar collectors, which combine both of these functions, can significantly improve the efficiency of solar energy utilization. Computer modeling is an essential tool for analyzing the thermal characteristics of such systems. It allows for the study of heat transfer processes, the identification of optimal design parameters, and the operating conditions of the collector, which can improve its efficiency. Modeling also provides the opportunity to predict the system's behavior in various climatic conditions and under different loads, an important step in the design and optimization of such devices. The authors developed a model of a hybrid thermal solar collector that simultaneously acts as a transparent building shield and a solar collector. Using the SolidWorks software suite, the thermal processes of solar energy collection in the developed collector design were simulated, and the temperature variations in the collector and accumulator tank were analyzed under constant solar intensity. The main principles of temperature increase in the system throughout the experiment were determined. Based on the modeling results, the change in the instantaneous specific thermal power of the proposed hybrid solar collector design was obtained, as well as an analysis of its efficiency coefficient. The research results showed that a significant increase in the performance of hybrid collectors is achievable. The impact of parameters on thermal efficiency was analyzed, along with the need to identify optimal design solutions for further implementation. This opens up opportunities for further development of more efficient hybrid solar collectors, which will contribute to the expansion of renewable energy use within the global energy system.

This article presents the characteristics of a flat air jet flowing in the compressed conditions of a small room. The air jet compression ratio, axial and transverse relative velocity profiles, characteristic points on two axes in the vertical plane, which determine the velocity value equal to half the axial velocity, were determined. Graphs were constructed and empirical formulas were obtained. The purpose of the research is to study and investigate the regularities of the development of a flat inflow air jet in the compressed conditions of a small-sized room, to establish graphical and analytical dependencies to determine its parameters and also to create a mathematical model to explain the aerodynamic processes of a flat compressed air jet. The flat air jet provides proper attenuation of the tidal air flow velocity in the compressed conditions of a small-sized premise.

In a manuscript the results of research of the characteristics of a flat air stream with a variable mode of its flow into the room depending on time and current position are presented. Analytical equations for calculating the flat air jet parameters were derived. Numerical modeling of the incoming air stream in the variable mode was carried out due to CFD FLUENT (ANSYS FLUENT) software using the k–ε turbulence model. Method of a four-parameter numerical simulation of the flat incoming airflow in the variable mode is devised.

In this article the specific heating and cooling capacity of the ceiling TABS was determined. The step of tube laying varied and was 10, 15, 20, 25, and 30 cm. Determination of the specific heating capacity was carried out for th /tc = 35/31; 36/32; 34/30 oC. The determination of the specific cooling capacity was carried out for tcold /theated = 15/18; 16/19; 16/20oC. The radiant heating system based on ceiling TABS allows providing the necessary heating capacity to fully cover the heat loss of the room. The maximum values of the carrier temperature are th /tc = 34/30 oC. In the warm period, the ceiling TABS does not allow to provide the necessary cooling capacity of the room. Thus, the greatest cooling capacity of TABS is observed at coolant parameters tcold /theated = 15/18оC, which allows covering about 70% of the estimated heat gains of the room. Therefore, during the hours of peak heat gains an additional cooling device should be used in the room.

These researches concern the application of renewable energy sources in district heating systems. In Ukraine, district heating systems cover approximately 50% of the demand for thermal energy in the residential and communal sector. District heating systems 2G are most often used, which are characterized by high temperatures of the heat coolant, the lack of accounting for heat energy consumption during transportation of the heat coolant, and the use of fossil fuels. In the countries of the European Union, the introduction of district heating systems is considered one of the key directions for the transition to a decarbonized, environmentally safe and efficient energy system. The development of district heating systems technologies makes it possible to lower the temperature of the heat coolant in heat networks and increase the use of renewable energy sources. Ukraine will eventually become a full-fledged member of the European Union, and this determines the need to find ways to bring Ukraine's heat supply systems to the 4G level, in particular to low-temperature district heating systems with the most efficient use of renewable energy sources and waste heat. This article examines climatic, physical-geographical and social features, regulatory, technical and financial-economic opportunities and barriers to the implementation of low-temperature district heating systems in Ukraine. As a result of analytical studies, it was established that there are prerequisites for the introduction of low-temperature heat supply systems in Ukraine, however, a number of technical, regulatory, social and financial and economic measures need to be implemented to bring district heating systems up to 4G indicators. These studies allow establishing measures that require further research for the possibility of introducing low-temperature district heating systems in particular and environmental safety of heat supply systems in general.

AbstractThis article is dedicated to diagnosis of damage to air distribution in a room with twisted, compact, and flat air jets, and to searching of ways to solving the problem. It was found that in order to avoid damage to the air distribution system in rooms of different purposes and dimensions; it should be air streams of the appropriate types and with the appropriate characteristics. Parameters of a swirled, compact, flat, rectangular air jet when creating comfortable climatic conditions in the rooms of different purposes and dimensions are determined. The relationship between the angle of inclination of the rotating plates (for twisted jets), ratio of sides of the slit (for all rectangular including compact and flat streams) and a long-range of these flows is established.

AbstractThe research was conducted for three types of houses, including a panel house built before 1991, a brick house built in 2006, and a brick house built in 2022. It was established that the temperature difference, which is decisive when assessing the sanitary and hygienic condition of the premises, does not exceed the normative values for buildings built after 2006. In the building since 1991, the sanitary and hygienic indicators of the heated room deteriorate when the outside air temperature drops below −3 °C. At the same time, the fulfillment of the first condition of comfort in the room occurs at indoor air temperatures higher than the standard value, therefore, under the calculated conditions, residents feel discomfort when staying in such a room.

This work is devoted to increasing economic efficiency when using two-stream air distributors that form a swirled and flat stream while providing a dynamic microclimate in compressed conditions of industrial premises. The design of a two-jet air distributor is proposed, which forms a swirled and flat laying air jet, that provides intensive attenuation of air flow velocity and temperature in stationary and variable mode. Measures aimed at saving cold energy are considered, namely, air supply in a variable mode, use of the flooring effect, use of devices for intensification of tidal flow turbulence. A set of optimal measures for obtaining the maximum economic effect is determined. A method of development and calculation of inflow mechanical ventilation systems based on the specified air distributors is proposed. The economic evaluation of the use of air distribution devices proved that the use of a two-jet air distributor makes it possible to obtain some economic effect. Received: 4 September 2023 | Revised: 18 October 2023 | Accepted: 28 January 2024 Conflicts of Interest The authors declare that they have no conflicts of interest in this work. Data Availability Statement The data that support the findings of this study are openly available in AKJounals at https://doi.org/10.1556/606.2021.00419, in Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu at https://doi.org/10.33271/nvngu/2021-2/104, and in Sciendo at https://doi.org/10.30657/pea.2021.27.22.

Energy and economic assessments are of great relevance in the context of decision processes for the most optimal solutions for building renovations. Following the method recommended by UNIDO, economic analyses of thermal modernization options are carried out based on the Simple Payback Time (SPBT), Net Present Value Ratio (NPVR) and Internal Rate of Return (IRR) indices. Incorporating these indicators and a new approach that involves aggregating thermomodernization activities not only in the cold and warm seasons separately, but throughout the whole year, an economic evaluation of the thermomodernization of a production space was carried out. In this case study, the renovation options included wall insulation, window replacement, the installation of infrared heater, a two-flow air diffuser (TFAD) and variable air volume. The economic effect indicated by the highest NPVR over a normative period of 15 years was obtained for the installation of an infrared heater and a TFAD with a variable mode ventilation system. The SPBT for this case was also the lowest.