This article presents an analysis of the operation of a mechanical supply and exhaust ventilation system with heat recovery under future Polish climate conditions. The tested ventilation system was equipped with an electric preheater and a plate heat exchanger for sensible heat recovery. The system’s operation was analyzed using the SSP-RCP scenarios from the IPCC Sixth Assessment Report (AR6), as well as recent Typical Meteorological Years from 2001– 2020. The energy demand for air treatment and transport was assessed. The impact of expected Climate Change on the amount of energy, both recovered in the plate heat exchanger and required to be introduced from alternative system, was analyzed. Changes in the amount of energy recovered in the plate heat exchanger and the share of energy covered outside the air handling unit were also analyzed, compared to the results of the TMY. Six Polish cities were selected for the study. The analysis included climate change scenarios SSP1-2.6, SSP3-7.0, and SSP5.8.5 for the years 2050 and 2080.