Buildings, although one of the largest energy consumers in the world, also represent big potential to reduce energy consumption, dependence on fossil fuels and carbon dioxide emissions, through the implementation of energy efficiency measures. Improvement of energy efficiency of existing buildings requires a dedicated, serious and detailed approach. Investors are often guided by economic criteria, which greatly influence on investments and interventions, potentially causing some negative side effects (comfort reduction, use of energy-intensive materials, etc.). Therefore, it is very important to rely on methods that provide detailed and affordable cost, technical and environmental analysis. Energy efficiency methods are often based on simple methods such as research, estimation of energy consumption, preliminary design, estimation of energy savings and financial cost-effectiveness. For example, in energy audits of buildings, annual energy consumption and cost-effectiveness are considered for analysis. For a more detailed assessment, a calculation tool based on the calculation of energy consumption of particular facility and the estimation of energy savings after the proposed energy efficiency measures is being used. The proposed measures generally represent a classic scenario of energy efficiency measures. In this paper, factors such as comparison of the share of fossil fuels and renewable energy sources (RES), the estimation of cost-effectiveness of the use of renewable energy technologies, aspect of embodied energy in materials and life cycle assessment in buildings are being considered. This paper defines the criteria for the evaluation of scenarios (functional groups of measures) for increasing energy efficiency of the building, which include, in addition to energy and economic aspects, environmental aspect. The six criteria have been defined for evaluation of energy efficiency scenarios related to: annual energy consumption, total annual primary energy, share of RES in primary energy, direct and indirect carbon emissions, embodied energy in applied materials and investment per scenario. For each criteria an expression for its calculation is given. Defined criteria are calculated for six scenarios of increasing the energy efficiency of Mechanical Engineering Faculty, University of Sarajevo. Based on the calculated different values of criteria of considered aspects, it is possible to identify in more detail way critical points, advantages and disadvantages of different combinations of energy efficiency measures, which can further serve to identify the best strategy necessary for evaluation of energy performance of the building before and after the intervention.

Linear viscoelastic materials whose characteristics are suitable for description by the Prony series use experimental data to obtain the so-called “master” curve. The analysis of experimental results with the Prony model sometimes requires prior knowledge of the time parameters of the model ,, in order to make the corresponding module more suitable for use in analytical form. In this way, the existing model is optimized to some extent, while in this paper the approach is used that all parameters in the Prony series for (E i , τ i ) were determined using the well-known least squares method and its variations. The number of members in Prony’s series is initially smaller and increases proportionately. To determine the relaxation modulus using the Prony model, an example from an available article [1] was selected in this paper, while the performed experiment was used to determine the creep modulus. During the performance of the load experiment, the function of constant increase (ramp-test) was used. The previous experiment was done for the actual material ABS plastic (Acrylonitrile butaden styrene).

Building envelope has significant role in the building sector. It represents immediate interaction between outside and inside environment. In dependence of its characteristics and opposed requirements, it affects on achievement of the thermal comfort of inside area and closer environment. Existing standards in the building sector dictate air tightness of an envelope, limiting air infiltration with the aim to save energy, but also influence on the inside environmental quality in situation when optimal air quality cannot be achieved due to the insufficient ventilation of the room. Besides that, building envelope in dependence of its characteristics, under the influence of Sun light, can less or better absorb heat flux and cause the temperature rise on the surface of the building. Specific characteristic of material to absorb and retain solar thermal heat, in urban environments, contributes more and more to the presence of the phenomenon known as urban heat island. For interaction of the building envelope with the environment factors, the building of Mechanical Engineering Faculty was chosen as a case study, on which the measurement of the envelope surface temperature was performed with the aim to empirically confirm presence of higher temperatures on building envelope. At the same time, the measurement of indoor air quality parameters, as carbon dioxide concentration, inside air temperature and relative humidity was performed, to estimate ventilation efficiency of inside area. Results of the measurement have shown the presence of relatively high surface temperature on the building envelope, which is the in accordance with the earlier research about the existence of higher surface temperatures in dependence of its characteristics and environment. Measurement of indoor air quality parameters showed higher carbon dioxide concentrations, especially in winter semester, which values exceeded by 60 % of recommended ones. Higher carbon dioxide concentrations are result of insufficient ventilation of the room, and it is indicator that optimal cooling system with frequent ventilation is necessary criteria that needs to be fulfilled to achieve quality inside environment from the aspect of the comfort, productivity and health of users. In the recent years, there has been noticed evident increase of the outside temperature, especially in urban area due to the construction and characteristics of applied materials in buildings, resulting also in the climate change. It is necessary to emphasize that planners and designers in the conceptual stage of construction or renovation of the buildings, incorporate solutions and decisions about the materialization of the envelope, which will affect on the reduction of urban heat island, considering as one of the energy efficiency measures.

Aim of the research was measuring the heat transfer coefficient of the external walls at the Mechanical Engineering Faculty building with heat flow method, in order to obtain the real value of heat transfer coefficient. After performing the measuring according to the ISO 9869 for in-situ measurement, the average measured heat transfer coefficient was 0.23 W/m2K, which is lower value compared to the calculated one, 0.33 W/m2K, according to the program (KiExpert). Difference between values is the result of limitations in selection of materials and because heat accumulation in building elements is not sufficiently considered in algorithms of the program.

Pneumatic conveying involves the transportation powder, granular and piece of material and is based on the phenomenon that at the appropriate speed of air in the pipeline, the solid particles are brought in the desired direction. If inlet air velocity is too high the material flow rate may be reduced, the power requirements will be excessive, and operating problems will be severe. Considering the advantages that air-slide conveyors can offer in relation to pneumatic conveying systems especially in terms of low power consumption and operating problems associated with abrasive particles, such as erosive wear of system components and degradation of friable particles. In this paper is presented design calculation of airslide conveyor in the thermal power plant.

Research is the viscoelasticity properties composite of wood made by gluing beech peeled veneer and at constant load, and two constant humidity. Based on the experimental results obtained by the method of the least squares rheological parameters have been determined as well as their differences in relation depending on the moisture content of samples. Has been developed and applied numerical model based on the finite volume method analysis of viscoelasticity properties composite of wood. Starting with the continuum concept we presented and broadened the application of the finite volume method for solving of the hygro-viscoelasticity behaviour of the composite of wood. Have been ignored of anisotropy in wood, and observation of the sample as homogenous, non-layered material, and also neglect of glue. We developed the constitutive relation including the impact of moisture, expressed through relaxation functions and given in integral form. The calculation results are compared with results of the experiment