Air-conditioning is commonly used to achieve thermal comfort in commercial buildings in the hot and humid Southeast Asian Region. Because of high initial costs, high energy consumption and often unacceptable indoor climate (SBS, noise, draught) some European countries do not recommend full air-conditioning and sometimes even prohibit it. Alternatively, heating and cooling may be done by water-based radiant heating and cooling systems, where pipes are embedded in the building structure (floors, ceilings, walls) or in the centre of the concrete slabs in multi-storey buildings. During the last two decades, radiant floor heating applications have increased significantly. In Germany, Austria and Denmark, 30% to 50% of new residential buildings have floor heating. In Korea, about 90% of residences are heated by under floor systems. This paper is focused on this Hydronic radiant cooling for commercial and institutional buildings.