Energy saving performance testing of vacuum water flow window under hot summer and cold winter climate

By applying vacuum glazing (VG) to water flow window, a novel vacuum water flow window (VWFW) is raised in the current study. Its advantages in reducing thermal transmission through windows and enhancing thermal utilization against common double layer water flow window (DWFW) and triple layer water flow window (TWFW) are tested in a hot summer and cold winter climate. The impacts on room heat exchange and water pre-heating performance, as well as the thermal utilization efficiency are compared. In cooling season, room heat gain through the VWFW is found reduced greatly comparing to DWFW, the reduction is in the range of 6%–38%. While those of VWFW and TWFW are comparable because of the high supply water temperature. The other benefit of VWFW is the increased water heat gain. A higher water heat gain efficiency in the range of 34%–70% is achievable with VWFW, this is 7%–30% and 3%–12% higher than those of DWFW and TWFW. In heating season, the VWFW is advantageous in reducing heat loss to ambient and increasing the thermal utilization efficiency. This is more promising under the cloudy day and higher supply warm water temperature conditions. •Vacuum water flow window.•Thermal performance testing.•Enhanced thermal insulation.•Increased thermal efficiency.•Improved thermal comfort.