High-temperature cooling & low-temperature heating AC system evaluation of energy saving in an office in Tokyo.

While the efficiency of water piping central AC systems has improved greatly, improving in the efficiency of the overall system had been a problem that needed to be solved. The High-Temperature Cooling & Low-Temperature Heating AC System (WATER EXCEL) centers on using a medium temp. refrigerant, having a large temp. difference between the inlet/outlet of a heat-exchanger, having low temp. air-blow, adjusting control of OA/RA volume at the chamber room and ensuring a radiant and laminar flow. A new specification has been established “10;10;13”. We took measurements in an office building in Tokyo for one year to evaluate the energy-saving properties and comfort of this system. New specification “(1)10;(2)10;(3)13” refers to reference temperatures for an energy transfer medium. (1) Cold water temperature is 10°C (improved heat source efficiency by shifting from the conventional 7°C to 10°C toward middle temperature). (2) Coil doorway difference of temperature is 10K. (reduction in pump power by having a larger temperature difference from 5K to 10K and water volume reduction). (3) Cooling air supply temperature is 13°C (reduction in blowing power by reducing air volume from the conventional 16°C)