Neglecting building indoor air quality while pursuing other energy efficiency goals, such as tighter building envelops, can result in building environments that negatively impact the health, comfort and productivity of occupants (sick building syndrome) and therefore defeat the overall goal of building design, including reduced costs. Smoking areas, schools, labs, hospitals and positive pressure buildings will need even higher attention due to their higher ventilation rates requirements. Fresh air ventilation using a dedicated mechanical outdoor air system became a very important component for modern HVAC system design. The HVAC designer must therefore implement creative solutions to meet both conflicting requirements in an optimum manner.

This study evaluates the energy savings potential of indirect evaporative cooling (IEC) as fresh air pre-cooling in hot climatic conditions in Saudi Arabia. For this purpose, a commercial IEC unit was pilot-tested in a building located in Ras Tanura refinery. The IEC unit effectiveness and water consumption were monitored and verified against published performance data. Energy saving calculation method for hybrid IEC/DX-based AC system was performed and a generalized energy saving chart was generated for various simulated climatic conditions using Ras Tanura building example. Depending on the climatic conditions observed, results show that fresh air pre-cooling using IEC has an energy savings range from 10% to 70% when compared to using DX-based AC system alone. Results are consistent with literature information and should be of a great value to enable HVAC designers evaluate quickly the energy savings potential when applying IEC as fresh air pre-cooling.

Fresh air pre-cooling using indirect evaporative cooling (IEC) offers a great energy saving and emission reduction opportunities. In a pilot test at one of Ras Tanura buildings, the effectiveness and energy performance of a commercial indirect evaporative cooling (IEC) unit were monitored and evaluated. An energy saving calculation method for fresh air pre-cooling using a hybrid IEC/DX system was presented and subsequently further expanded to cover a wide range of simulated climatic conditions. Energy savings chart developed in this study will provide HVAC designers with a tool to evaluate quickly the potential percentage energy savings when applying fresh air pre-cooling using IEC as opposed to using DX-based system alone, which is estimated to be between 10% and 70%.

Download the Full Paper

Additional Resources

Indoor Air Facts No.4: Sick Building Syndrome