Summer performance of ventilated windows with absorbing or smart glazings

• A CFD model of ventilated window is built to find U-factor, SHGC and total heat gain.
• The optimal spacing between the two panes is determined based on NFRC standards.
• Different types of glazing are considered, including electrochromic glazings.
• Performance under off-design conditions for smart windows is studied.
• A simplified model based on scale analysis is also proposed.

This work investigates the benefits of ventilated fenestration on the energy performance through the analysis of ventilated windows in skycrapers and commercial buildings with criteria such as the U-factor and the SHGC. Fenestration considered are double glazing units made of exterior glazings with different absorption properties. In particular, a more in-depth analysis is performed with ventilated glazings integrating electrochromic filters which are known to have high absorbing properties. A numerical model is implemented in a CFD commercial software to determine the total heat gain reduction provided by ventilated glazing units compared to insulated units used under hot climates. An operating design is proposed as well as an optimal spacing between glazings in order to obtain best performances.