The purpose of the article was to present information on heat recovery in ventilation systems and to highlight what has not been sufficiently researched in this regard. A lot of information can be found on methods and exchangers for heat recovery in centralized systems. Decentralized, façade systems for cyclical supply and exhaust air have not been sufficiently researched. It is known that these devices are sensitive to the influence of wind and temperature, hence heat recovery may be ineffective in their case. The literature describes the aspect of heat recovery depending on the location in climatic zones, depending on the number of degree days (HDD). Attention was also paid to the risk of freezing of heat recovery exchangers. The literature review also showed the lack of a universal method for assessing heat recovery exchangers and the method of their selection depending on the climate.