Today, in many buildings the cooling requirements are already higher than the heating requirements. The reasons for the increased cooling requirements and the lower heat consumption are obvious. The heat consumption is lower in buildings which are thermally insulated to a high standard while the cooling requirements increase due to higher solar energy gains. Demands for more comfort and convenience are rising and larger internal heat loads are also on the increase. Cooling requirements are increasing especially in commercial buildings such as doctors’ practices and offices due to the waste heat from electrical devices and lighting. Therefore, apart from heating, the efficient cooling of buildings must increasingly be taken into consideration.