Valentina Turanjanin

Phase change materials (PCMs) integrated into lightweight building envelopes were experimentally evaluated to assess their impact on indoor thermal performance. A PCM test house and a reference test house were examined under two conditions: without ventilation and with night ventilation. The experiments were conducted under the climatic conditions of the Republic of Serbia, in Belgrade, at the Vinca Institute of Nuclear Sciences. Two observation periods were defined to evaluate the thermal behaviour of the test houses, with four thermal cycles monitored in each period. Results indicate that, on hot sunny days, the PCM test house achieved maximal indoor air temperature reduction of 3.5-4.8 ?C during the non-ventilated period and 4.2-5.9 ?C during the night-ventilated period, while reducing thermal load levelling (TLL) by 64.1-72.5% and 45.5-49.5%, respectively. The average indoor temperature reduction (AITR) ranged from 0.03-6.12% in the first period and from 3.19-6.54% in the second, confirming the potential of passive PCM application for improving indoor thermal stability. These findings show the practical benefits of PCMs in enhancing energy efficiency and indoor thermal comfort in lightweight buildings.

In addition to the grains as the main agricultural product, the agricultural production of soybean also produces large quantities of plant residues in the form of soybean straw. The article focuses on the primary trends in soybean production worldwide, and Serbian's current position in global production. The paper analysis the dynamics and structure of sown areas, gross harvest volumes and soybean yields in the world for the period 2006-2023 in the context of leading producing countries. Soybean straw is an agricultural leftover that yields up to 1.5 kg per kg of soybeans. The existing literature demonstrates the vast potential of soybean straw as an environmentally friendly source of carbon to produce chemicals, materials, fuels and energy similar to oil refineries. The possibility of using untreated soybean straw for the synthesis of building materials was considered. Different types of common cement were used as starting raw materials for synthesis. The characterization of two test samples was performed using X-ray diffraction analysis (XRD), light microscopy (LM), thermal conductivity and heat capacity measurement.

The Environmental Protection Agency of the Republic of Serbia continuously monitors and collects air quality parameters at numerous measuring points throughout the country. The results revealed that the levels of air pollution recorded during the lockdown differed from those recorded during the same period the previous years. In this paper, we examined pollutant concentration trends in 2020 and a few previous years to determine the underlying causes of these trends. Pollutants are measured at five stations in Belgrade from the beginning of March to the end of July between 2015 and 2020. Because no hourly data were available, nitrogen dioxide, sulphur dioxide, and suspended particles PM10 and PM2.5 are average daily values, whereas carbon monoxide and ozone are daily 8-hour maximums. Concentrations were compared and averaged only when data for the same period over time was available, i.e. when comparing 2020 to previous years. The results were compared to the annual and daily limit values (for ozone and carbon monoxide 8h maximums, respectively), as well as the variations in concentrations over time. The goal of calculating and displaying these values is to specifically identify a change in air pollution during the COVID-19 virus pandemic isolation period. In general, for Belgrade in 2020, NO2 concentrations are lower at four stations; PM2.5 concentrations are lower at two stations; PM10 concentrations are higher at one station and lower at another; and SO2 concentrations are higher than in previous years (2015-2019).

Energy costs are rapidly rising around the world and it is important to find a way to reduce energy consumption. Energy consumption in buildings can account for up to 40% of total energy consumption in developed European countries due to an increase in living space per person, an increase in the need for air conditioning, an increase in the number of appliances used in households, and other factors. Due to the increasingly frequent high temperatures during the summer and the increase in electricity consumption, it is very important to find a way to decrease indoor temperatures in urban residential buildings without using more energy, given the severe energy crisis that has engulfed Europe and the high percentage of energy and electricity consumption in the residential sector. Installation of phase changeable materials is one method for improving the thermal envelope of a building by increasing the thermal capacity of the envelope and thus affecting the reduction of indoor temperature oscillations and, consequently, reduction of summer electricity consumption. In this study, the TRNSYS software package was used to simulate and compare the indoor air temperature in typical detached houses built in period 1946 and 1970 in the Belgrade area, for both, the case without and the case with installed phase change (PCM). It was shown that incorporating a PCM with a melting temperature of 25?C into the inter-floor construction of the house could significantly improve comfort conditions by reduce indoor temperature fluctuations during the warm period without consuming additional energy. When the temperature outside is around 30?C, the maximum air temperature in the house drops by about 2?C.

Greenhouse gases emission as well as total energy consumption in buildings of public importance, such as schools, municipal buildings, health care centers, can be significantly reduced by increasing buildings? energy efficiency. Buildings? energy consumption adds up to 37% of total energy consumption in the EU countries. In the Republic of Serbia this amount is significantly higher, about 50%. School buildings are considered as one of the most diverse structures from the point of energy-efficient design and construction. The main aim of this paper is to determine the most appropriate settings for possible improvements in energy efficiency and temperature comfort inside a typical primary school classroom in Serbia. The energy efficiency analysis was performed during the heating season for the naturally ventilated primary school classroom located in the eastern Serbia region. The analysis was performed using novel CFD model, suggested in this paper. The suggested model was used to solve two hypothetical scenarios. The first scenario simulates the temperature field in classroom with current energy characteristic envelope of the school building. The calculated numerical data from the first scenario were compared with in-situ measurements values of temperature and wall heat fluxes and showed satisfying accuracy. The second scenario was simulated to indicate possible improvements, which would allow energy consumption decrease and thermal quality enhancement. The analyzed results, calculated using the suggested numerical model under the second scenario conditions, showed that using appropriate set of measures, it is possible to obtain desired temperature comfort levels without need for increase in the building energy consumption.

The district heating system in Serbia, with an installed capacity of 6600 MW, currently supplies 58 towns with thermal energy. As a candidate country for accession to the European Union, Serbia faces the obligation to reduce the level of its GHG emissions as part of environmental reforms. This paper presents a basic scenario and three alternatives for final energy consumption in the district heating sector for the years 2015, 2020, and 2025. It is suggested that demand for heating will increase 10% up to 2020 and by 15% up to 2025, in relation to 2015 levels, while the share of each energy carrier will not change. Changing the structure of energy sources for heat supply assumes a decrease in the share of coal and liquid fuel, and increases in the use of biomass and natural gas. The results obtained were compared to the General Index of Sustainability which is a measure of the complexity of the proposed energy scenario. The paper considers the formation of related energy indicators as quantitative tools for the analysis of changes. It also proposes a methodology for multi-criteria analysis in the sustainability assessment of complex energy systems based on the stochastic evaluation of criteria (sets of indicators and sub-indicators). In this way, the results of the multi-criteria assessment can help in the decision-making process in cases where economic, social and ecological criteria are considered to be influential.

New Regulations on energy efficiency in buildings in the Republic of Serbia legislate values for the temperature correction factor used to calculate the heat flux to the outdoor environment through construction elements of a certain type. The temperature correction factor is used to correct errors caused by calculation of heat losses based on the design outdoor and indoor temperature difference of building elements adjacent to unheated spaces which are in direct contact with the ground or external environment. Since the temperature correction factor directly influences the calculation of total heat losses and total annual energy demand, it is recommended that the temperature correction factor be determined on the basis of measured values of outdoor and indoor air temperature, or, on the basis of the values obtained by the simulation. This paper presents the results of measurements in the High School of Design, Textile and Management in Belgrade in order to assess energy efficiency and the energy performance of buildings. Data obtained on the basis of measurements, such as indoor and outdoor temperatures, are used for the calculation of the heat transfer coefficient for the building envelope elements as well as to calculate a temperature correction factor for the unheated attic space of the building. This paper also offers a dynamic simulation of the multi-zones building in the TRNSYS environment. The aim was to compare temperature correction factor values obtained from measured temperature values, with those calculated from standard, taken from the Regulation table and produced by simulation.

Sustainable development indicators mainly provide information that can link the observed energy system with sustainable development. This paper considers building energy indicators in order to provide monitoring and measurement of energy performance of buildings. The results of measurement which are considered were obtained in school buildings in Serbia. The aim of this paper is to select, define, and calculate energy indicators as criteria for evaluating the quality of public buildings, with regard to sustainable development. The criteria for assessing sustainability are quantified by certain defined sets of economic, social and environmental indicators. The ASPID method of multi-criteria analysis is also described and mathematically presented. This method is based on the synthesis technique of fuzzy sets and the sustainability of the school buildings was based on their assessment as complex energy systems.