The best solution for renovation in terms of climate and economy

EU aims to reach carbon neutrality by 2050. This means, that besides energy consumption reduction, also greenhouse gas emissions have to be cut starting from the production of materials and construction work through the use phase to the end of the use of the building. Existing buildings are estimated to provide a high potential for reducing global warming. This paper focus to research question, how reasonable are energy efficiency improvements of existing buildings, as the materials used in the process produce CO2 emissions and increase costs compared with conventional maintenance. This issue is a part of the UN Sustainable Development Goal 13 Climate Action. The carbon footprint of an existing renovated building constitutes mainly from energy consumption emissions. In life cycle costs, the deciding factor was investment. If the building was heated by zero-emission ground source heat, structural renovations would not be worth doing. On the other hand, structural improvement of energy efficiency is recommendable if building is connected to district heating. Strong reasons, either endogenous or exogenous, must exist for replacing an existing building by a new. They cannot be justified with the carbon footprint or lifecycle costs. These results apply to countries, where the energy efficiency of existing buildings is reasonably good.