This paper assesses the performance of photovoltaic (PV) technologies integrated into buildings in the desert climate and the factors that affect energy yield. Cadmium telluride (CdTe) and standard mono-crystalline silicon (c-Si) modules were installed facing south, in the three more common tilt angles used in the Building Applied Photovoltaics (BAPV) and Building Integrated Photovoltaics (BIPV) applications at the Dubai latitude (90°, 25°, and 0°). We monitored the energy production, the temperature of the PV modules, irradiance on each tilt angle, and the meteorological parameters for a full year. We then calculated the performance ratio for the six modules to evaluate the different factors, including temperature and soiling losses, following IEC 61724-1. The 25° modules, usual PV rooftop angle, had the highest and more consistent energy yield throughout the year. Conversely, the energy yield of the 90° modules, typical angle for facades, vertical shading devices, and guardrails, had the lowest yield and showed wide variations. This is expected as the 90° angle is more affected by the seasonal changes of the solar altitude. The soiling losses on these modules were lower than 1%. However, at 0°, the soiling loss was more evident, with an average reduction of 10.79%. The c-Si module at 25° generated the highest normalized energy yield of 402.02 kW h/m², which was 23.5% more than that of CdTe module with the same tilt angle.

Biomass gasification represents an efficient process for the production of power, heat and biofuels. Different technologies are used for gasification and this article focuses on a circulating fluidized bed (CFB) system. Understanding the behaviour of particles is of primary importance and a cold flow CFB experimental unit was constructed and tested. The particle circulation rate is greatly affected by the loop seal performance, and therefore the loop seal should be properly optimized to maintain an uninterrupted operation. Smooth flow regimes were obtained for the CFB by varying the loop seal aeration rates. Particles with size 850–1000 µm and 1000–1180 µm were chosen for the experiments. The minimum flow rates of air into the riser for the two particle sizes were found to be 1.3 and 1.5 Sm3/ min, respectively. To obtain a smooth flow regime, a velocity range for aeration in the loop seal was found for the two particle sizes. Based on the experimental results, combinations of flow rates were suggested for the simulations. A Computational Particle Fluid Dynamic (CPFD) model was developed using Barracuda VR, and the model was validated against experimental results. The simulated results for the system regarding the pressure and the height of the bed material in the standpipe agreed well with the experimental results. The deviation between the experimental and computational pressure was less than 0.5% at all the locations for both the particle sizes. The deviation in particle level was about 6% for the 850–1000 µm particles and 17% for the 1000–1150 µm particles. Both the experiments and the simulations predicted that a small fraction of the circulating sands are emitted from the top of the rig. The validated CPFD model was further used to predict the flow behaviour and the particle circulation rate in the CFB.

The effective utilization of natural ventilation in heritage buildings could save a significant rate of electrical energy, as the airflow pattern affects interior comfort conditions; achieving users’ thermal comfort counts as an added value. This study aims to promote an approach in the form of a design strategy for a developed optimal annual operating schedule for heritage buildings, targeting the best operating pattern/s for each month. The study was carried out for a typical heritage building in the central district of Alexandria city (a typical Mediterranean Basin city), Egypt, for improving energy efficiency while achieving users’ thermal comfort. The paper adopted a simulation methodology for conducting energy and thermal comfort analyses using DesignBuilder simulation software. The approach was applied to a south-oriented room of the selected residential heritage building, which is the most affected orientation in the temperate-humid (slightly warmer) climate. The developed operating patterns included closed and opened windows, controlled natural ventilation, and HVAC system for cooling and heating with different temperature setpoints. The results showed that using the developed optimal annual operating schedule can save up to 47% of the total cooling and heating electrical energy annually, while achiev- ing 365 thermally comfortable days a year, including 177 days when only natural ventilation operating patterns are used. The study revealed the importance of considering the optimal operating patterns schedule as an approach to improve the environmental performance of heritage buildings. Also, the optimal annual operating schedule resulted in an adjusted base-case that can be used for evaluating the retrofitting scenarios for south-oriented, energy-efficient heritage buildings in temperate-humid climate.

This paper presents part of the results of a large-scale, long-term experimental research conducted at the Faculty of Civil Engineering and Architecture Osijek. Among other research goals, this research aims at further development and improvement of a relatively new method used for the measurement of ther- mal transmittance of walls (U-value) in literature, often called temperature-based method (TBM). This research also partially overlaps with other researches carried out at the Faculty of Economics in Osijek, where the main research goals were development of machine learning and neural network models for predicting energy consumption in buildings, which will reduce the energy performance gap between design and actual energy needs. Building thermal performance as a whole can be quantified by the heat loss coefficient (HLC) or the total heat loss (THL). Experimental research presented in this paper was conducted by using a built test chamber in a laboratory, and the research lasted for 40 days. This is an innovative element of this research, since the test chamber is built inside a laboratory where external weather conditions are simulated by omitting the negative influence of wind, precipitation, and solar radiation on the experimental results. The actual heating energy consumption by the test chamber was recorded daily for 40 days during the winter season, together with internal and external temperatures, relative humidity (RH), U-values of walls, and wind speed. Chamber airtightness was measured at the beginning of the experiment. These measurements made it possible to perform the Co-heating test. This test is used to calculate the total heat loss of a building, both fabric and ventilation loss. Parallel with the Co-heating test, the design heating energy need of the test chamber was determined by calculating the heat loss coefficient and the total heat loss. Actual and design values of heat loss coefficient and total heat loss were used to characterize the energy performance gap. Energy performance gap in this study was found to be between −40% and 13%. Research results indicate the variables affecting the actual and design values of heat losses significantly. Presented results provide guidance for more accurate determination of actual energy consumption in buildings, and therefore help in the reduction of the energy performance gap.

The paper presents the results of a study in the field of a comprehensive economic assessment of the competitive advantages of cogeneration power sources in the context of economic imbalances.

In the course of the study, the theoretical and methodological aspects of the competitive development of energy cogeneration systems were studied. Thus, it is proved that for the methodological support of the process of constructing strategic tasks in energy-generating companies operating in energy cogeneration systems, it is necessary to develop specialized industry methodological tools for assessing business processes in the field of cogeneration. In addition, the revealed multilevel specif- ics of positioning cogeneration energy sources in the territorial energy market under the conditions of economic imbalances required creation of a special methodology to take into account the peculiarities of the development of energy cogeneration systems with the help of which it is possible to study the nature of the impact of economic imbalances that disrupt the normal course of the investment process in energy cogeneration systems.

Testing of the developed methodology showed that the relationship between the centralized and distributed energy cogeneration systems can be different depending on the market conditions and the state of the competitive environment. Thus, in addition to traditional steam turbine plants, in a centralized energy cogeneration system, priority should be given to cogeneration gas plants, as the most competitive in terms of efficiency and maneuverability, and in a distributed – to cogeneration gas turbine plants, mainly built on the basis of local boiler houses.

Despite the growing interest in the field of urban–industrial symbiosis as well as in sustainable energy solutions at the city level, a research gap is recognized in terms of analyzing the advantages of energy symbiosis networks between industrial and urban areas integrating renewable energy systems.

The urban–industrial symbiosis can support both urban transition toward sustainability and industrial green innovation through creating advantageous relationships in the framework of a common low-carbon strategy between industrial districts and neighboring urban areas. Urban–industrial symbiosis extends the concept of industrial symbiosis, a part of the industrial ecology field, to urban–industrial synergies. Taking advantage of the geographic proximity, it promotes the exchanges of waste, resources, and energy between urban and industrial areas, as well as the sharing of infrastructure.

Thus, the paper aims at presenting an in-depth analysis of the main urban–industrial symbiosis schemes based on low-carbon energy flows between industries and cities, investigating the energy syn- ergies potential. It introduces the concept and outline of sustainability-driven framework with the aim of modeling urban–industrial energy symbiosis networks integrating renewable energy sources from a multi-stakeholder point of view and supporting decision-making on the economic, environmental, and social sustainability of the energy synergies.

The article outlines new approaches to managing electrification that are driven by a radical transformation of scientific, technological, environmental, and economic conditions. These include spreading the use of electromechanical devices following the onset of a digital economy, the creation of highly efficient, small-scale power-generating units and lower cost of energy from renewable sources, wider economic collaboration between energy suppliers and consumers based on demand–response mechanisms, and stricter environmental regulations. The article defines the characteristics and trends of the new phase of electrification, assesses its contribution to economic growth and the environmental security of a region, and offers recommendations as to the optimization of the technological structure of the electric power industry in view of evolving requirements for greater reliability, environmental friendli- ness, and service support of power supply.

The authors bring out the principles of the provision of electricity to households in smart cities and identify the main areas of focus for increasing the economic efficiency of adopting innovative electrical technologies through a balance of national economic and business interests. A methodological toolkit has been designed for measuring the level of electrification in a region.