Experimental Assessment of Environmental and Economic Impacts of Dampers’ and Filters’ Faults in a Typical Air-Handling Unit in Southern Italy

Heating, Ventilation and Air-Conditioning (HVAC) systems are responsible of 50-60% of energy demand of the building sector. The scientific literature highlights that HVAC units are frequently operated under faulty conditions that can significantly affect their performance. In this paper, the performance of a typical single-duct dual-fan constant air volume Air-Handling Unit (AHU) is investigated through a number of experiments performed during Italian cooling and heating seasons under both fault free and faulty scenarios. The AHU operation is analysed while artificially introducing seven typical faults: return air damper kept always closed; fresh air damper kept always closed; fresh air damper kept always open; exhaust air damper kept always closed; supply air filter clogged at 50%; fresh air filter clogged at 50%; return air filter clogged at 50%. The faulty and fault free tests are compared to assess the environmental and economic performance impacts. The experimental data highlighted that the most adverse fault is that one corresponding to the exhaust air dumper kept always closed; in particular, it increases both the daily global equivalent CO₂ emissions and the daily operating costs up to 110% in comparison with the fault free conditions.