Retrofit of multi-family homes with central heat recovery ventilation, learnings from three case studies

This paper addresses the implementation of ventilation systems within the context of energy retrofit of residential buildings. Indoor air quality is a parameter of crucial importance when the airtightness of the building envelope is increased. A mechanical ventilation system is required and may strongly influence the energy demand of the building and the user comfort. Three German multifamily homes have undergone deep energy retrofits and have been equipped with central ventilation systems with heat recovery. An analysis of their implementation and of the results provided by a long-time monitoring is proposed. A definition of the heat recovery efficiency taking the electricity demand and primary energy coefficients into account is proposed and implemented to evaluate the performance of the three analysed ventilation systems. It can be concluded that the implementation of central heat recovery ventilation systems in the energy retrofit of residential buildings provides a high thermal comfort as well as good energy performances despite the differences between these performances and the ones expected during the planning phase and despite the difficulties to operate these systems correctly.