Optimized Design of Outdoor Cooling Systems for Open Areas in Hot Climate

The upper concourse is an external area with relatively high occupant density at the east side of Khalifa International Stadium which will host Qatar 2022FIFA World Cup. Tempering or ‘soft conditioning’ this area, which is necessary to prevent spectators from experiencing a thermal shock as they enter orexit the cooled bleachers, proved to be a very challenging task, further exacerbated by the severe weather conditions typical for Doha, with ambienttemperatures often reaching 47°C (116.6°F) in summer. A detailed Computational Fluid Dynamics (CFD) study has been conducted to investigate andoptimize an effective tempering strategy to alleviate hot air wind effects and establish an adequate thermal environment in the open upper-concourse of thestadium with the least energy expenditure. Specifically, the CFD study tests different cooling design options by conducting a detailed investigation of airflowdelivery and temperature distribution in the open space while considering external weather parameters such as temperature, humidity and wind speed, aswell as detailed internal heat sources such as body heat from occupancy, solar radiation, and heat gains from lighting and equipment. Several designparameters have been considered such as providing shades to protect from solar loads and winds, optimizing the supply air flow rate, speed and temperatureof the evaporative coolers, choosing the best air distribution layout and accounting for actual heat loads. The thermal comfort range was defined based on theprocedure outlined in Appendix F of ASHRAE 55-2010 which consists of calculating the SET (Standard Effective Temperature) thermal comfortindex. A hybrid system consisting of a radiant floor cooling with displacement ventilation at low level, combined with a continuous tent cover with limitedshades to maintain views for the spectators, proved to be a solid foundation for guarantying savings in energy costs while establishing adequate environmentalconditions in the upper concourse.