Faculty of Agriculture in Osijek High energy efficient building - 4eu / m2 / year energy cost Faculty of Agriculture with its usable area of 18.717 m2 stood 1.120 EU/m2 gross floor area, and serves as an example of a good and mindful project. This project achieved that the building of Faculty of Agriculture is certificated as an extreme low-energy type of building (Class A (19 W/m2k) by energy spent for heating, cooling, ventilation, lighting and hot water. Today it is the most successful low-energy public building (faculty) in Croatian framework. In addition to energy savings, there is also comfort and sense of well-being in a place where there is no serious temperature fluctuations, and the air is regularly changing. Guiding principle for the new building was the sustainability and low maintenance costs. The collaboration of architect, designer, mechanical and electrical engineers was therefore essential from the starting point. All this resulted in modern and smartly sized heating and cooling system that uses ground water, using a heat pump that heats and cools over 3,600 tons of concrete core (capillary action through a reinforced concrete floor slabs and walls), which serves as a reservoir for heating and cooling. Mechanical components of the system are mostly technological innovation: heat pumps, water source system wells and wells water sinks, cooling the air in the air chambers, thermally active concrete constructions - ceilings and walls, thermally active surfaces for floor heating and cooling, passive cooling of the building using the well water, the use of the atrium as the exhaust system volume ventilation, use of glazed atrium roofs for solar contribution in winter mode. Smart lighting and motion sensors that automatically switch on and off systems in areas where there’s no one also help lower energy consumption. Environmentally the building is recognized in the form of solid single volume, predominantly glazed, with broad public and covered pedestrian drive into the ground level. At the southern end there is the entrance of large volumes accentuated by bold classrooms, whereas the northern facade is characteristic for its congress hall with rounded glazed surface. The building is in an east-west direction split into two parts, and in north-south direction in three parallel tracts, associated with five transverse corridors so that six internal free spaces (atrium) arise above the ground floors. On the ground floor is a central tract completely built on reinforced concrete columns because of the important archaeological site. All atriums are covered with glazed roof. The interior of the building is intertwined with network of corridors that lead to classrooms, laboratories, research laboratories, offices, library, deanery, deanery hall, administration, student facilities, etc., all grouped by departments needed to educate students and scientific research within the Faculty of Agriculture. Rational and intelligent design, and extremely economical construction has resulted in a very cost-effective maintenance. The project has by its disposition and functionality met all these requirements, while establishing a new, high standard of public faculty buildings in architecture at the same time.