Full-Scale Unit-Space Measurements and Annual Heating and Cooling Load Evaluation of a Medium Office Building with Different Low-E Coating Configurations of Vacuum Double Glazing

Purpose: Vacuum glazing offers very low U-values with relatively high solar heat gain, which is beneficial for heating-dominated dwellings but may increase cooling loads in office buildings. This study therefore examines how different Low-E coating configurations of vacuum double glazing affect annual heating and cooling loads in a medium-sized office building. Method: A full-scale mock-up with three identical test rooms was built at H-University in Daejeon, and an initial test with identical double glazing was conducted to confirm comparable thermal behavior among the rooms. Three glazing types (a proposed dual-Low-E double vacuum glazing, a dual-Low-E triple glazing, and a commercial single-Low-E double vacuum glazing) were then installed and monitored. U-values and SHGCs derived from WINDOW 7.8 were applied to an EnergyPlus model calibrated to measured indoor air and window surface temperatures in accordance with ASHRAE Guideline 14, and the calibrated glazing models were implemented in the ASHRAE Medium Office prototype (Daejeon TMY3) to evaluate annual loads of the second-floor north and south perimeter zones. Result: Compared with conventional double glazing, the high-performance glazing systems achieved approximately 10 to 20% annual load reduction in the north zone and up to about 30% reduction in the south zone, indicating that a balanced design of U-value and SHGC through appropriate Low-E coating configurations is essential when applying vacuum glazing to cooling-sensitive office buildings.