Sandro Nižetić

Realisation barriers in energy efficiency projects in Croatian public buildings: a critic overview and proposals

ABSTRACT This paper discusses in detail specific barriers to establishing energy efficiency policies in Croatian public buildings that affect the realisation of energy efficiency projects. Barriers were discovered after years of collaboration with public institutions in Croatia, especially at a local level. Although the information presented in this paper relates specifically to the geographical areas of Splitsko- Dalmatinska and Dubrovacko-Neretvanska counties in Croatia, the research can be generalised to the country as a whole. The paper also analyses the important role of the United Nations Development Programme in encouraging proactive energy efficiency policies in public buildings in Croatia. Finally, a new organisational framework is proposed to eliminate existing barriers and to establish a system which will lead to the effective realisation of energy efficiency projects in buildings. The research presented in this paper should also be useful to countries facing similar barriers to energy investments.

Solar Assisted Organic Rankine Cycle for Power Generation: A Comparative Analysis for Natural Working Fluids

In this study, a comparative thermodynamic analysis of a solar assisted organic Rankine cycle (ORC) is carried out for different natural working fluids. The required heat energy demand for ORC is supplied by solar energy by means of parabolic trough solar collectors (PTSCs). For the ORC system, eight different natural working fluids those are suitable for low temperature applications such as R170, R1270, R600, R600a, R717, R744, R218 and R161 are analyzed comparatively. Also the analyses are made for R134a in order to compare the system performances. The calculations are made according to the solar flux distribution in Turkey. For the results, the energy and exergy efficiencies and exergy destruction rates of the ORC system for different working natural fluids are compared in detail. From the results of energy and exergy analyses, the best fluid is found to be R744 with a power generation rate of 4.87 kW with an energy and exergy efficiencies of 8 % and 7.1 % respectively. Also it is found that R218 has the highest exergy destruction rate as 76.98 kW. Additionally, the effects of turbine inlet temperature, turbine inlet pressure and condensation temperature on system performance are parametrically analyzed.

Comparison of Aluminum and Copper Particle Critical Diameter Produced in Overhead Line Conductor Clashing

The issues of hot metal particle eruption due to overhead line conductor clashing and potentially ignition of cellulosic fuel beds under the transmission line have not been sufficiently explored although conductor clashing is often considered as fire cause. At the point where contact or electric arc between two conductors on different potentials is established, electric energy is converted into heat energy so the large amount of generated heat can cause melting and vaporization of conductor material. Some of ejected sparks will ignite and burn, while others will simply fall to the ground, cooling off on the way by convection and radiation. The critical diameter is the least diameter of the particle caused by conductor clashing that will be sufficient to ignite the biomass on the ground. The results show that the copper particles in the same conditions bring a greater ignition risk due to their higher heat capacity.

Comfort Sensation Versus Environmental Aspects in Office Buildings

Both environmental aspects and comfort sensation are parameters of high priority for the construction and design of buildings. Considering that the existing European building stock is a major energy consumer, it is clear that its environmental aspect should be improved. Therefore, an evaluation of the indoor environmental parameters was conducted in office buildings, located in Thessaloniki, Greece. In order to carry out the environment evaluation, a revealed preference survey is conducted, determining the occupants’ perceived comfort sensation. In detail, an inferential statistical analysis is conducted, specifying the statistically important correlations, regarding the perceived occupants’ comfort sensation and productivity along with a variety of environmental relative parameters, focusing on thermal comfort, health, and well-being of the occupants’ based on integrated green certification schemes for buildings, such as BREEAM and LEED. Therefore, the vision of a green, not only regarding the energy consumption but also the occupants, building can be accomplished.

Design scenarios for renovation of sports complex: a case study

ABSTRACT This paper elaborates design scenarios for a sports complex in Croatia from a technical and economic aspect. Different energy options are analysed and two are additionally addressed and discussed as the most viable ones. The possibilities of sports complex renovation are shown by properly choosing the appropriate energy concept and thus reducing the overall cost for produced thermal energy by around 33% and reducing the carbon dioxide emission by a factor of 1.8 in comparison with its present state. Finally, this study presents an example of good practice, where renewable energy solutions can be proposed and where it is possible to cover around 70–80% of overall yearly costs from achieved energy savings for the novel plant that is assumed to be financed through a bank loan.

Effective ventilation strategies for net zero-energy buildings in Mediterranean climates

ABSTRACT The impact of ventilation strategies on the energy performance of new and existing buildings located in the Mediterranean is the main objective of the study. Several design criteria have been implemented in a base case reference model of a residential building, in order to achieve the net zero-energy balance target. The basic ventilation scenario adopted in the study as a reference, involved the moderate application of natural ventilation in summer months. Various modifications of this ventilation strategy that include the gradual scaling-up of the ventilation rate and the application of mechanical ventilation have been simulated, and their effect on primary energy demand required photovoltaic (PV) capacity and indoor thermal conditions evaluated. The results of the analysis indicate that the application of mechanical ventilation resulted in considerable increase of energy demand, up to 20%. Although the implementation of mechanical ventilation provides better control of indoor temperature distribution, the induced increase of energy consumption along with the installation and maintenance costs render such a solution less suitable for residential buildings in the Eastern Mediterranean, compared to natural ventilation.