Optimization of the Public Buildings Energy Supply: the case of the school in Koprivnica

There is a rising interest in the improvement of energy efficiency in public buildings nowadays atthe EU level. Increasing energy efficiency can lead to both better thermal comfort, as well as netsavings on energy bills. Furthermore, the right choice of energy source can lead to large savings inCO2 emissions. Recently, there have been a lot of projects in Croatia concerning the renovation ofschools. However, many of them do not take the holistic approach during the refurbishment projects.They rather focus on a partial solution, focusing only on heating or heating and power supply.Furthermore, the choice of heating furnaces is often based on old and inaccurate data, without anymid or long term planning. In order to solve this issue, a simple to use continuous linear optimizationmodel has been developed, which calculates the best investment options for heating, cooling andpower supply. The model has a variety of choices and chooses the optimal one based on the externalconditions entered, such as hourly temperatures, wind speed and global insolation. The model useshourly time steps during one year, while the objective function of the developed model is tomaximize net present value of the project.The model was validated on a case of Antun Nemcic Gostovinski primary school in Koprivnica,Croatia. The school has 728 pupils and 77 employees and is open from 08 AM to 08 PM everyworking day. It also has two adjacent gyms, kitchen and the library. The model showed thatsignificant savings could be achieved by taking a holistic approach during the refurbishment of thebuilding, at the same time increasing thermal comfort of the students and employees. Finally, thedeveloped model would be easy to adapt to any other similar public building, which could lead tofurther savings in energy consumption.