A field survey was carried out in a tropical building, which focused on the energy conservation potential of the radiant slab cooling system. A comparison was made between the energy performance of the radiant slab cooling system and a conventional all-air system. It was found that the use of radiant slab cooling in conjunction with an integrated air-side system was able to reduce the energy cost by 34%. The payback time for using the combined radiant-convective system was only about 2.5 years. More savings can be obtained by setting higher return air temperatures during off-peak hours in working days.