The thermal performance of skylight glazing affects more than heat transfer. It can also influence interior surface temperature, condensation risk, cooling demand and occupant safety.
Condensation-risk reduction
The vacuum cavity in vacuum glazing is maintained at very low pressure, with very limited residual gas and moisture. Meanwhile, the improved thermal insulation of the glazing helps maintain the interior glass surface at a temperature closer to the indoor environment.
This can reduce the risk of condensation under appropriate environmental conditions.
For buildings such as hospitals, museums, schools and commercial spaces, where indoor humidity and environmental stability can be important considerations, improved glazing thermal performance can contribute to a more stable interior environment.
What about cooling demand?
Vacuum glass skylights can improve thermal control and reduce heat transfer through the glazing. However, the actual impact on cooling demand depends on factors including skylight area, solar exposure, climate, building envelope, glazing configuration, HVAC system and operating conditions.
A comparative experiment simulating solar radiation on skylight glazing was conducted at 21 time points between 9:31 and 16:01.
During the heating stage, the temperature inside the test chamber with conventional insulating glass was approximately 1.0 to 2.5 degrees Celsius higher than that with vacuum glass on average. The maximum temperature difference reached 2.53 degrees Celsius.
At approximately 2:00 p.m., the maximum temperature difference reached 2.78 degrees Celsius.
During the cooling stage, the temperature reduction of the vacuum-glass test chamber was 1.35 degrees Celsius smaller than that of the conventional insulating-glass test chamber. The overall daily temperature fluctuation was reduced by approximately 8 percent.
These results represent the tested setup and conditions and should not be interpreted as direct whole-building energy savings.
Safety for overhead glazing
LandVac vacuum glass skylights can be designed with a vacuum + laminated composite structure. In the event of glass breakage, the PVB interlayer helps retain broken glass fragments and can reduce the risk of falling fragments, subject to the specific glass configuration and applicable safety requirements.
This combination of thermal performance and laminated safety makes vacuum glazing suitable for demanding overhead glazing applications where both energy performance and safety need to be considered.
