The set of design temperatures adopted in the sizing of the district heating systems has direct consequences on both the heating system size and the energy losses in the distribution network. This paper establishes the correlation between the two issues mentioned and attempts to identify an optimal set of design temperatures of the heat carrier to be chosen in sizing the heating system for buildings connected to district heating systems.

This study investigates the use of non-biodegradable wastes namely plastic water bottles and recycled glass in the construction of flexible pavements which, conventionally, uses bitumen as the binder and cement or stone dust as the filler. Consequently, the binder and filler were modified using varying percentages of pulverized plastic and recycled glass powder respectively. The modified binder showed improvement in properties when compared to the unmodified bitumen. The asphalt produced thereafter using the modified materials indicated a stability of 3.33kg obtained at an optimum value of 6% plastic replacement which is higher than the 2.017kg obtained without modifying the bitumen.

The levels of greenhouse gases in the atmosphere are increasing since the industrial revolution. The main cause is associated to anthropogenic activities. Contrarily to what has been observed to atmospheric carbon dioxide levels, the evolution of the atmospheric methane concentration is still not fully understood. A relative stagnation of the methane concentration was observed from 2000 to 2006. After that, the levels of methane continue to increase. The global methane budget is assessed using two different approaches. It is verified the existence of inconsistencies between the results obtained from them. A better understanding of the methane cycle is needed to reduce the discrepancy and uncertainties associated to the methane sources and sinks and its quantification. This would allow a more reliable image of future scenarios.

Systems for Domestic Hot Water (DHW) preparation generally represents a considerable part (up to 35%) of energy and water consumption in hotels worldwide. As a consequence of that, a vast amount of heat is wasted through the drainage system from rooms and kitchens. Also, in hotel type of buildings, according to their occupancy, demand for DHW can vary. Researchers and practitioners have a very challenging task to select optimal and sustainable solution. This paper describes a DHW heating system operation with a heat pump system which use Grey Waste Water (GWW) and rainwater energy source. The application is developed in combination with experimental site measurements (real system operation) and required standards. The proposed system consists of three energy source parts: the main heat pump system, heat accumulation tanks, and gas boiler as a reserve. In order to evaluate application of the selected heat pump DHW heating system, a comprehensive assessment was carried out with the conventional gas boiler (base case) and solar collectors system. Assessment results for optimized heat pump system operation showed a very good economic indicators (PBP=4.5%, POP=5.1%, IRR=16% and MIRR 13%). The analysis confirmed the main advantages of this heat pump system which are (consists of) lowered energy consumption and reduced total operating costs. Also, this study results can be used for the planning of hotel DHW systems as an example of the best available system selection. In the end, the research presented encouraging practical application as a cost-effective hotel DHW heating system.

The distribution network is an essential part of all urban water supply systems that requires efficient design and operation, which may be achieved through effective application of optimisation methods. This paper provides a briefly overview of the most approached methods for optimisation of water distribution networks (WDNs) design and operation. The main deterministic and heuristic optimisation techniques are synthesised and described, and several optimisation models in literature, which used these methods for WDN design/rehabilitation and operation are indicated. Finally, the advantages and disadvantages of the optimisation techniques for urban WDNs are presented.

The paper presents the basic schema of energy certification and auditing procedures for the two basic thermal components of district district heating: heat exchangers and thermal distribution network. After the constructive-functional identification of the components, their energy efficiency is evaluated based on experimentation and the energy efficiency obtained with the theoretical efficiency established in two functional reference variants. Describing the energy certification procedure on the basis of energy notes and assessing the additional unjustified energy dissipated for energy auditing, taking into account the investment costs of the proposed rehabilitation solutions

The design of new water supply networks as well as the reconstruction and modernization of the existing water supply networks is highly dependent on the calculated water demand for the urban population and its various needs. The aim of the paper is to make a comparison of urban water needs in Romania, Ukraine and Slovakia, considering different categories of consumption specific to apartment buildings. Using large diameters for the water supply network pipes will cause a decrease of the drinking water velocity, therefore the duration of stay in the water network will increase and chances for worsening the water quality will be higher. On the opposite, using small diameters for pipes will cause an increase of the water velocity, which will increase the head losses in the distribution network, causing significant energy demands for pumping. After presenting the technical legal framework concerning water demand calculation in Ukraine, Slovakia and Romania, a comparison was made for the selected apartment buildings and also for urban green areas watering. From the calculated results of total water demand it can be stated that the difference in water demand for the neighboring areas of Ukraine, Slovakia and Romania is significant.

This study assesses the performance of selected intersections in Akure, Nigeria. The identified intersections were Road block, Bye-pass and Cathedral intersections. Data for this study which included traffic volumes was collected through semi-automatic method, personal observations and questioning of individuals. The results of the data analysis revealed that the Level of Service (LOS) for Road block intersection was critically low (LOS = F) due to on-street parking and the absence of traffic signals to aid drivers. Likewise, the LOS for Cathedral intersection is low (LOS = E) while that of Bye-pass (LOS = C) appears to be adequate.

This paper presents an experimental stand for the study of energy conversion and storage. The hybrid system has as component elements: water- water heat pump, the supply system of the heat pump with flow control, storage tank of the waste water discharged from a water-water heat pump, compressed air storage tank, compressor, Pelton turbine, photovoltaic system for electricity supply of the system, automation system, load resistance, wattmeter. With the help of the experimental stand were determined: the running idling characteristic of the electric generator at different simulated turbine drop and the operating characteristic under load. Thus, the efficiency of the system has been demonstrated by increasing the Coefficient of Performance (COP) of the heat pump.

Building sector in Serbia is the most energy intensive of all economic sectors with some data showing the buildings are accounted for nearly 50% of final energy consumption of country, large portion of consumption related to covering building heating and cooling needs. New EU Directives covering energy efficiency and energy use target refurbishment of existing buildings, as well as the construction of new ones in a direction to represent nearly zero energy buildings (nZEB). Although the building stock turnover rate is very low, even in the most developed countries, and the energy retrofits of existing building stock towards nearly Zero Energy Buildings are becoming more important compared to new buildings, the HVAC system selection while designing new buildings could be the corner-stone for achieving nZEB goals. In this paper, energy performance of one residential building type in Serbia was analyzed with different combinations of HVAC secondary and primary systems, with several levels of building envelope thermal properties, as well as for several locations spreading north-south across Serbia. The heating and cooling energy consumption in all cases was contrasted with electricity produced from roof-mounted PV central, and it is found that electricity produced from roof area is more than enough to balance the energy consumption of the legislative-required refurbished building, from the primary energy perspective.