Analysis of Seasonal Exergy Efficiency of an Air Handling Unit

Ventilation systems play an important role for providing suitable indoor climate in buildings. Improving these systems allows promoting energy efficiency in building sector, which is responsible for a large percentage of global energy consumption. Therefore, this work focuses on assessment of ventilation air handling unit (AHU) using thermodynamics. The exergy analysis is used to evaluate the performance of an AHU. Special attention is made about seasonally varying exergy flows of a system. As efficiency of a ventilation system is closely linked to local climate, especially to the varying reference temperature. The paper presents an approach for calculating the seasonal exergy efficiency and gives the results of the AHU analysis. The case study reveals that the highest exergy consumption is when the outdoor temperature is -2.5 degrees C. The AHU case with heat recovery and water heater is the most efficient comparing to other cases investigated. The use of this methodology may be extended for determining of the seasonal exergy efficiency of any other HVAC equipment.