Urban landscape is largely characterized by high degree of built space, high share of artificial surface material and the reduction of green areas, which leads to changes in the microclimate and the deterioration of thermal comfort in outdoor urban space. One of the most important roles of urban greenery is the impact on the reduction of air temperature due to less heating of green space compared to paved surfaces and due to tree shading. The paper analyses the influence of urban greenery on temperature reduction. Aim of the study was to measure the difference in warming up of grassy surfaces and paving materials commonly used for public areas and to evaluate the impact of tree shading on the surface cooling during the day. For this purpose, measuring of surface temperatures was performed during the summer months in 2015 in the central city zone of the city of Nis. The measuring included: grass, asphalt as most commonly used paving material, and concrete tiles commonly used for pedestrian areas. Results show the temperature of grass is significantly lower than the temperature of paved surface at any time of day. In the case of paved surfaces, temperature of shaded or partially shaded material is lower than the temperature of surface exposed to sunlight during the whole day, a temperature difference exists even after nocturnal cooling. The results indicate the importance of green areas for cooling of urban spaces, due to their lower warming and surface shading from tree canopy. IntroductionUrban environment is defined as the physical environment in urban areas, with its complex mix of natural elements (including air, water, land, climate, flora and fauna) and the built environment, i. e. a physical environment constructed or modified for human habitation and activity encompassing buildings, infrastructure and urban open spaces [1]. The process of urbanization brought about changes in cityscape, reduction of green areas and increase of paved areas, and the changes of city climate and emergence of so called urban heat islands (UHI). The UHI represent the areas inside cities where the air temperature is higher than the air temperature of the surrounding area. With higher temperatures, energy consumption in-_______________ Djekić, J. P., et al.: The Study of Effects of Greenery on Temperature Reduction …

Original scientific paper https://doi.org/10.2298/TSCI170531123M Solar radiation in Serbia is for about a third higher than in Middle Europe, which represents a very favorable energy potential. Southeast Serbia is a leading area in this aspect, since the annual average of daily global radiation on a horizontal surface exceeds 4.2 kWh/m 2 . This paper compares four photovoltaic power plants installed in southeastern Serbia. Analyzes are done based on results from two years of power plant exploitation. The power plants are not located in the same areathere are differences between topography and altitude of their locations, which is also taken into account during analyzes. Photovoltaic modules have different orientation and inclination toward horizontal surface, and their capacity varies from 30-40 kW. The conclusion provides recommendations for improvement of production where it is actually possible.RES. This goal was laid out through obligatory national sub-goals, which took into account different starting points of the member states [2]. Regarding solar energy, the White book of the EU from 1997, set a goal that by 2010 the total capacity of installed photovoltaic (PV) systems should reach 3 GW [3]. The predicted PV solar system capacity was reached earlier than planned and already by the end of 2008, the total capacity was 9.5 GW [4,5]. More than half of European PV power plants were installed in Germany, approximately 5.3 GW and about 1/3 in Spain. Since 2005, solar PV electricity generation capacity has increased from 1.9 GW in 2005 to 80.7 GW by the end of 2013, and the 2020 National Renewable Energy Action Plan (NREAP) target of 84.4 GW was exceeded, fig. 1, by the end of 2014, reaching about 88.4 GW [6]. Energy Law of the Republic of Serbia set the legal framework and the ability to use incentives in the production of electricity from renewable sources.

This paper presents some basic urban and architectural requirements regarding the installation of solar panels for electricity production on buildings. These requirements are usually designaesthetic and functionalconstructive. However, from the thermal ambient aspect, constructor's solution is often not in accordance with requirements of architectural and urban planning profession. It is a known fact that thermal environment impacts the yield in the solar panels production. The aim of this paper is to show, based on experience of solar power plant DOMIT, city of Leskovac, Serbia, what is the expected effect in that aspect, in order to choose the optimal solution with regard to the character of the building. The most favorable production have solar power plants built on buildings where the panels on the underside are completely open because they have the best ventilation, and therefore cooling.