The Balassi Bálint County Library was built based on the plans of architect József Finta. On 6 June 1988, it was handed over to the demanding users of the 4 919.6 m² “Cultural Palace”. The new building brought many opportunities for the library and readers. In addition to the traditional library frameworks, there were research rooms, exhibition halls, lecture halls and fairy tales. The mechanisation of workflows, the use of information databases and the Internet also brought a qualitative change in the life of the library. In recent years, the library has expanded its services and has become one of the most visited cultural institutions in the city. The work has become necessary because the building has worn out in recent decades and no longer meets the requirements of today’s heat engineering. The renovation will greatly reduce maintenance costs and make the building much more economical. In addition, the lower energy demand for heating will also reduce emissions, so they will do more to protect the environment.After the completion of the works, institutions that meet today’s energy standards and environmental aspects can be acquired. This will not only be reflected in the maintenance costs, but will also provide a much more comfortable environment for those who use the building. Within the framework of the tender, the heating can be upgraded, partial insulation, heat recovery ventilation, solar panel installation, and the proportional accessibility of the project will be completed. The building is under local protection. The roof is insulated with a 20 cm stone wool plate. Waterproofing with 4 mm thick rubber plate. At the top of the building there is a two-water-nosed wall covering with foil tin. In order to reduce the filtration loss planned for the modernisation of heating, the 30.000 m³/h air treatment system will have a heat recovery system with a minimum efficiency of 70 % and therefore significant energy savings can be achieved. The planned solar panel is a 40 kWp solar panel with an expected yield of 48.000 kWh/year, which significantly reduces the institution’s energy consumption. It is expected that 160 solar panels will be installed, connected to the public electricity distribution network and accounted for by an ad-take meter. The building needs protection against summer overheating, which we want to implement with shaders. More detailed technical-professional content will be included in the construction plans. Self-eligible activities: Energy efficiency-oriented development of municipal-owned buildings by modernising their external boundaries. Construction of a small power plant (HMKE) photovoltaic system with a maximum household size to meet its own electricity demand: installation and installation of solar panels and their supporting elements;according to a static opinion, the reinforcement of the relevant load-bearing elements of the roof structure; the purchase of the elements necessary for connection to the local electricity system and to the grid shall be the costs of the network developments which are essential for internal connection and the costs of their deployment; equipment for measuring and recording electricity produced. Mandatory non-eligible activities to be carried out on its own: accessibility in proportion to the project, publicity and training. Optional, ineligible actions: Modernisation of central ventilation systems: installation of heat recovery equipment.