The main objective of the project is to increase energy efficiency in an office building for rent, located in Poznań through a deep comprehensive thermal modernisation. The project meets the basic objectives and objectives of priority axis I of the OP, as its implementation will reduce the consumption of non-renewable primary energy, as well as positive effects on the environment by reducing emissions of harmful substances into the atmosphere. The objective of the project stems from diagnosed needs, including the need to reduce energy consumption, save heat and reduce CO2 emissions into the atmosphere, eliminate fuel oil consumption as well as improve room use, increase the competitiveness of the economy and improve the environmental image of the company. The implementation of the investment will increase energy efficiency by 87 % (in terms of final energy) to achieve the following result indicators: Estimated annual decrease in greenhouse gas emissions (CI34): 88 tonnes of CO2/year •decrease of final energy consumption as a result of the project by 1531.83 GJ/year •Reduction of primary energy consumption by 1375.57 GJ/year •The amount of thermal energy saved: 733.23 GJ/year The project also contributes to achieving the strategic objectives: •Reducing emissions of harmful substances to the environment: CO2, particulates SO2, NOx •reducing fuel consumption •reducing the unemployment rate in the region •decreasing the so-called. “acid rains” •decrease of the so-called phenomenon. “low emissions” •improving the conditions for economic growth