• Energy Research
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The paper includes a general discussion of reasons for the application of heat storage and phase change material as storage medium. A part of experimental results obtained by measuring during the process of paraffin phase change was presented. It was observed that in order to obtain lower temperature stratification during the heating process it is necessary to increase the number of volume heat sources in the thermal storage. .

The energy efficiency of typical rural houses in Serbia is presented in this paper. Typical houses from rural areas were analyzed by proper measurements, and by numerical calculations according to current regulations. The first house is a traditional Vojvodina house and it is situated in the suburban part of municipality of Sremska Mitrovica. The second house is a typical Serbian mountainous house and it is located in the municipality of Ra{ka. Experimental data for the analysis were obtained by performing measurements of temperature, humidity and dew point on the characteristic spots in these houses. Recording with thermal imaging camera were also done. Detailed insight in energy performance of observed houses can be defined by analyzing obtained results. Calculation of the annual energy needs for heating is based on the Regulations on energy efficiency of buildings in the Republic of Serbia, which were adopted in 2011. It was concluded that the annual energy need for heating in rural homes significantly exceeds optimal limits for objects of that category, so the special attention should be devoted to analysis of energy efficiency problems in rural areas.

Biomass can be considered strategic potential, not only because it is a renewable source of energy and it is widespread, but also because its application can provide a sufficient amount of energy to reduce emissions of CO2 and other greenhouse gases, resulting in a minimum negative impact on environment. This paper presents an overview of techniques for biomass burning, as well as technical and technological characteristics of plant for the production of energy from biomass in order to promote the implementation of renewable energy sources. It also presents the option and joint combustion of biomass and fossil fuels. The decisive factor in the increased use of biomass should be its low acquisition and operating costs, but the application of modern low-emission incinerator is economically viable only for large plants, because then gets maximum effect from the problem of fuel (straw and specially planted Culture (Miscanthus Sinesis)). .

Refurbishment of existing building stock using energy-saving phase-changing smart materials and technologies, in addition to improved indoor climatic conditions, offer an opportunity for increasing housing energy efficiency and value. This fast developing technology becomes increasingly cost-effective with much shorter payback periods. However, it is undertaken only on a limited scale; because of lack of knowledge about their changeable properties and dynamism in that they behave in response to energy fields. Main characteristics, which make them different form others, are: immediacy transience, self-actuation, selectivity and directness. Phase change processes invariably involve the absorbing, storing or releasing of large amounts of energy in the form of latent heat. These processes are reversible and phase-changing materials can undergo an unlimited number of cycles without degradation. Since phase-changing materials can be designed to absorb or release energy at predictable temperatures, they have naturally been explored for use in architecture as a way of helping deal with the thermal environment in a building. Technologies based on sealing phase-changing materials into small pellets have achieved widespread use in connection with radiant floor heating systems, phase change wallboards, mortar or facade systems. Thermal characteristics of existing buildings can be improved on increasing their thermal-stored mass by implementation products of phase-changing smart materials. In addition to contributing to carbon reduction and energy security, using phase-changing materials in the building sector stimulates innovations.

The paper highlights certain open methodological issues relevant to the analysis of the comparative politics and climate change law. The second part of the paper focuses on the basic elements of the law and politics of the climate change in Bosnia and Herzegovina, Montenegro, Croatia and Serbia. For the basis of the analysis several criteria have been taken: membership in the international treaties, status in the UN Framework Convention on Climate Change and reporting, the existence and development of the climate change legislation (the constitutional provision, content and availability of regulations, climate change in the framework environmental law), the existence of the specific regulations governing the rational use of the energy and renewable energy sources, as well as the level of compliance of the national legislation with EU regulations. Having identified some differences in the state of national regulative on climate change (primarily between Croatia and other countries) the paper expounds the thesis that the key factor that determines the status of national policies and regulations (of the states under this analysis) is the process of the European integration. In conclusion of the analysis it is estimated that the progress in this process is directly correlated with the level of the development of national legislation and implementation of international obligations.

Buildings are among the top of energy consumers. It is estimated that over 50% of the overall produced energy is consumed in buildings, mainly on heating and cooling. Application of air conditioning systems saw an important expansion in the past decade. These systems are used, not only for cooling but for heating, or supplemental heating, as well (as heat pumps). While there is virtually no alternative to their usage as cooling systems, heating applications should be reconsidered in a more subtle manner to maintain the principles of energy efficiency. Mass consumption of air conditioners has as an effect a significant rise in consumption of energy, mainly during the summer. Aesthetic consequences are another important problem. Since the placement of these appliances is not regulated by law, and left to the citizens they are commonly self-initiated and misaligned which undermines aesthetic values. Additional problem is placement of air conditioning systems on protected objects (religious institutions, object under protection) which undermines not only aesthetic, but historical value as well. On the other hand, many new buildings represent a positive example, since this problem is adhered from the very start of conceptual design, and these appliances are covered with adequate architectural solutions. This paper will try to cover positive and negative examples of Serbia, Montenegro, and some other Balkan and Western Europe's countries. It will also give recommendations in solving the negative energy and aesthetic consequences of these problems. Non-controlled application of air conditioning systems is becoming a health problem. Large differences between the interior and exterior temperature leads to an array of health problems registered by many medical reports. Improper maintenance of air conditioning systems could lead to bacterial propagation which could seriously damage health.

This paper present the results of examination of wood of four black locust clones (Robinia pseudoacacia L.) R34, R56, R113, R121, in different ages - 6,8,11 and 13 years. Growth ring width, fiber length and wood volume density (oven dry and basic) were determined. For all tested roperties significant differences were found caused by different clone and different age of wood. The highest average growth rate - the width of growth rings was recorded up to the eighth year (mean 5.40mm), while the average fiber length of 0.866mm increased with age of trees. Mean values of wood density of 672 kg/m3, which is in an older wood range up to 780 kg/m3 , confirm a significant possibilty of using black locust wood as renewable energy source.

The overview and analysis of the most important standards in the field of energy efficiency drives, in our country and abroad, are presented in the paper. Special attention is paid to standards relating to the efficiency and control motor speed.