Can switchable smart glazing improve solar heat gains and daylighting in educational buildings?
Revit Plug in
For copy of full dissertation, contact:
Dr. Sameer Mehra
Even though switchable glazing has grown in popularity and specifiers are keen to use it, the benefits of switchable smart glazing do not trump alternative glazing types in terms of daylighting and solar heat gains.
As is commonly understood buildings are significant consumers of global energy supply. The facades of these buildings are responsible for an appreciable amount of this consumption. ''57% of the average building energy use is from the façade, the windows contribute to 6% of this''. 1 This study explores the impact of glazing specification and focuses on switchable smart glazing, a product which alters transparency from clear to opaque when heat, light or voltage is applied and evaluates whether there are benefits to it in terms of energy efficiency, privacy and enhancing occupant comfort.
There are a variety of switchable glass systems mainly broken into non-electrically actuated systems and electrically acutated. While they broadly aim to provide the same effect the mechanics of each slighly differ. This study was carried out on a specific type of electrically actuated solid filled switchable smart glazing, Suspended Particle Device (SPD) glazing. The study involved an occupant comfort survey to determine the comfort levels of students and staff in their current campus building. A case study building was used with a revit plug-in, FenestraPro to compare regular double glazing, Low-E and SPD in terms of daylighting and solar heat gains. An annual daylighting percentage was generated for the whole building, while the solar heat gains were based on two classrooms on the first floor of the building, one North facing and one South facing. Manual calculations were done to validate the results. The results were then evaluated to determine whether SPD showcases subtantial benefits over the alternatives.
The results obtained suggested that the benefits of switchable smart glazing are orientation dependant, and do not trump alternative glazing types. Regarding both daylighting and solar heat gains, they are mostly within the optimum or recommended levels year-round, which suggests there is never a requirement for the opaque transparency state. Results for solar heat gains on the North facade proved no requirement for the glazing as both states of transparency fell below optimum. While the South facade showed the glazing within optimum or slightly exceeding, the alternate opaque state was too low.
Switchable smart glazing may be more beneficial in hotter climates.