A Graphical Tool to Estimate the Air Change Efficiency in Rooms with Heat Recovery Systems

• Published in: Sustainability 2020-02, Vol.12 (3), p.1031
• Main Authors: Meiss, Alberto, Padilla-Marcos, Miguel Ángel, Poza-Casado, Irene, Álvaro-Tordesillas, Antonio
• Format: Article
• Language: English
• Subjects: Age; Air flow; Air quality; Air supplies; Air temperature; Efficiency; Energy; Flow pattern; Green buildings; Heat; Heat recovery; Heat recovery systems; Indoor air pollution; Indoor air quality; Indoor environments; Sustainability; Temperature gradients; Ventilation
• ISSN: 2071-1050; 2071-1050
• DOI: 10.3390/su12031031

Indoor air quality in buildings must be guaranteed for the health and comfort of the occupants. In order to assess the ventilation strategy of a considered room, the parameter of the air change efficiency ( ε a ) can be used. The objective of this work is to provide designers with a graphical tool for a reliable estimate of the value of ε a of a room. The temperature gradient between the outdoor air supply and the indoor air is so low that the ventilation flow can be assumed as isothermal when high-efficiency heat recovery systems are used. By means of charts, the optimal location of the openings for a better ε a can be determined during the design process, in order to subsequently apply them. It is concluded that it is very important to consider the ε a in the case of openings located in facing walls given that its range varies between 40% and 65%. In contrast, its use can be obviated in the case of openings located in non-facing walls, as the value of ε a obtained is close to 50%; this means a perfect mixing air flow pattern, which is the reference value for the estimation of the indoor air quality (IAQ) in the different national regulations.