Energy saving obtainable by applying a commercially available M-cycle evaporative cooling system to the air conditioning of an office building in North Italy

We analyze the energy saving obtainable by coupling a commercially available M-cycle evaporative cooling system to a conventional refrigeration cycle, for the air conditioning of office buildings in North Italy. The analysis is performed through the dynamic simulation of a case study. The hourly energy needs for cooling, dehumidifying and air change, during July and August, of a real office building located in Milan are considered. The climate of Milan is humid in summer, so that the example refers to critical conditions for the application of this technology in Italy. Two systems with M-cycle evaporative cooling are analyzed and compared to a traditional system: M-cycle pre-cooling of the external air, coupled to a refrigeration cycle; M-cycle cooling of the recirculated air, coupled to a refrigeration cycle with heat recovery. The results show that the second application of the M-cycle offers the best performance: it yields a 37.6% reduction in energy extracted by the refrigeration cycle, a 76% reduction in heating energy, and a 38% reduction in the total use of electric energy, under the assumption of electric heating. The reduction in heating energy is due to avoiding reheating after dehumidification, without decrease in thermal comfort