This article contains the analysis of the impact of using photovoltaic panels in a sample landmarkedwooden building. The analysis takes under consideration the potential for reducing primary and final energy building demand indicator. In the analysis of the impact of using a PV system on primary and final energy building demand indicator, a variant with using PVgenerated power as it is produced, and also that of storing part of the produced energy in the power grid, are taken into account. The performed analysis resulted in the conclusion that taking into account the impact of storing part of power in the grid while calculating building energy demand results in a significant reduction of FE and PE indicators, and also in it becoming possible to meet the WT2017 and WT2021 requirements in landmarked buildings in which thermomodernisationmight cause the loss of their value as landmarks. Keywords: energy performance of a building; landmarked building; PV system; final energy indicator; primary energy indicator.