Multi-stage optimization and multi-criteria decision-making for HVAC system energy retrofit of a lecture room

The energy retrofit of a partial recirculation all-air HVAC system serving a university lecture room located in southern Italy is analysed. Mmulti-objective optimization and multi-criteria decision-making are used to find optimal design alternatives and rank them considering two different decision-makers, i.e., public and private stakeholders. The results show that, in the post-pandemic era, baseline retrofit scenarios for infection reduction that do not involve installation of inverter devices and automatic dampers cause energy consumption increase from negligible values up to 59%. Contrariwise, baseline retrofit scenarios involving the installation of inverter and automatic dampers cause energy consumption decrease between 5% and 38%. In this last scenario, for the implementation of further deep retrofit intervention solutions, there is no agreement between decision-makers on the preferable retrofit solution. In the case of operation of the system with 100% outdoor air + inverter and automatic dampers, both stakeholders agree on the same deep retrofit solution.