Pfluger, R.R.PflugerSpeer, C.C.SpeerFeist, W.W.FeistWeger, J.J.WegerZgaga, J.J.Zgaga2022-03-042022-03-042013https://publica.fraunhofer.de/handle/publica/23330110.1002/bapi.2013100692-s2.0-84883094256Development of a highly efficient counterflow heat recovery fan for use in building modernization. Ventilation systems with heat recovery should be designed as energy efficient and compact as possible, especially if it should be applied in an existing building. A combination of fans and heat exchanger gives the chance to meet both requirements. An existing combination of fan and heat exchanger however shows a limited performance (48 % sensible heat recovery). This paper provides a modified concept with an enhanced heat recovery rate of more than 80 %. The design principles as well as the calculation procedure of the main design parameters are published.dejournal article