Performance evaluation of indirect evaporative cooling using whole-building hygrothermal simulations

In an indirect evaporative cooling (IEC) installation the return air is cooled by adiabatic humidification. In an air/air heat exchanger this air cools down the supply air. This paper presents a simulation methodology focusing on the interaction between the thermal performance of an IEC system and the heat and moisture balance of the building where it is applied. The thermal effectiveness of an IEC system is first studied by measurements. It was found that the effectiveness is independent of the air inlet conditions. In the second part the influence of the ventilation rate, the indoor moisture production and the moisture buffering capacity on the thermal performance were evaluated using dynamic calculations with the multizone building simulation program TRNSYS. Increasing the indoor moisture production and lowering the ventilation rate both reduce the thermal performance of the system. Hygroscopic materials may ameliorate the applicability of IEC.