E-mail Subscription
A: Vacuum glass can help reduce solar heat gain and maintain a more stable indoor temperature when used in skylights. Compared with conventional insulating glass, its high-vacuum cavity significantly reduces heat transfer, helping reduce the cooling load and improve indoor thermal comfort.
Measured Comparison: Vacuum Glass vs. Insulating Glass
A comparative solar irradiation experiment was conducted to evaluate the thermal performance of vacuum glass and conventional insulating glass when used as a simulated skylight.
The experiment was conducted from 9:31 to 16:01, with temperature data recorded at 21 time points under simulated skylight solar irradiation. Identical insulated test boxes were used, with vacuum glass and insulating glass respectively installed on the top to simulate a skylight structure.
The measured results showed:
During the heating stage: The average temperature inside the insulating-glass test box was approximately 1.0–2.5°C higher than that of the vacuum-glass test box, with a maximum average temperature difference of 2.53°C.
During the hottest period: At around 2:00 p.m., the maximum temperature difference reached 2.78°C, with the vacuum-glass test box maintaining the lower temperature.
During the cooling stage: The temperature drop in the vacuum-glass test box was approximately 1.35°C smaller than that of the insulating-glass test box.
Overall temperature stability: The temperature fluctuation of the vacuum-glass test box was approximately 8% lower, indicating a more stable thermal environment throughout the test.
These results demonstrate that vacuum glass can slow down indoor temperature rise under solar irradiation and reduce temperature fluctuations compared with conventional insulating glass. This makes it particularly suitable for skylights, roof glazing, sunrooms, and other applications exposed to direct solar radiation.
What Does This Mean for Cooling Energy Consumption?
For buildings with large skylights or roof glazing areas, reducing solar heat gain can help lower the cooling load during hot weather. The actual electricity savings depend on factors such as glazing area, local climate, solar radiation, building orientation, shading, HVAC efficiency, indoor temperature settings, and operating hours.
For large high-ceiling spaces such as hotel atriums, hospital courtyards, and commercial skylight areas, the potential reduction in cooling demand can translate into meaningful long-term energy savings.
Therefore, rather than evaluating skylight glazing only by its visible light transmission, it is important to consider its thermal insulation, solar heat gain, and ability to maintain stable indoor temperatures.
