Regulations, standards and guidelines have over time defined various indicators of heat recovery, some of which are also formulated as minimum requirements.
Unfortunately, these definitions, e.g. for the temperature efficiency RWZ or the permissible auxiliary energy required for operation, are often different, which confuses the experts concerned and leads to uncertainty.
The correct use is additionally made more difficult by the distinction between residential ventilation and non-residential ventilation. Different geographical areas of application (national and international) create further confusion. An analysis of the existing definitions in Europe, especially in the German-speaking countries, should help to bring some order to this confusion and create an overview.