Hydronic radiant cooling - preliminary assessment.

A significant amount of the electrical energy used to cool non-residential buildings equipped with all-air systems is drawn by the fans that transport the cool air through the thermal distribution system. Hydronic systems reduce the amount of air transported through the building by separating the tasks of ventilation and thermal conditioning. Due to the physical properties of water, hydronic systems can transport a given amount of thermal energy and use less than 5% of the otherwise necessary fan energy. This improvement alone significantly reduces the energy consumption and peak-power requirement of the air conditioning system. Radiant cooling has never penetrated the US markets significantly. The scope of this survey is to show the advantages of radiant cooling in combination with hydronic thermal distribution systems, as compared to the commonly used all-air systems. The report describes the development, thermal comfort issues, and cooling performance of the hydronic systems. The peak-power requirement is also compared for hydronic systems and conventional all-air systems.