Liquid-filled solar glazing design for buoyant water-flow

A water-flow window was constructed at the front wall of an environmentally controlled test cell to monitor its performance under full-scale real-building-like condition. The window was consisted of three layers, including one layer of clear glazing at the outside, one layer of insulated glazing unit at the inside, and one layer of water flowing in between. A heat exchanger was provided at the top of the window, and connected to the glazing cavity through connecting pipes and distribution headers. Through this, a cold feed water circuit removed the absorbed heat away from the buoyant water circulation in the window circuit. The heat removal allowed a reduction of energy consumption in air-conditioning and services hot water systems. Year round energy performance was then predicted by numerical models, which were successfully validated by the experimental data. A comparative study was also carried out with the use of different glazing types. The economical payback periods of the different glazing combinations are found less than 5 years under the Hong Kong subtropical climate. Amongst these, the energy performance of water-flow window with double absorptive glazing appears to be most promising.