Effect of smart glazing with electrochromic and thermochromic layers on building's energy efficiency and cost

This paper investigates the effects of various smart glazing configurations, including electrochromic and a combination of electrochromic and thermochromic layers, on a real office building in Athens in terms of annual primary energy use and Net Present Cost (NPC) through simulations in EnergyPlus. In order to identify the most influential building characteristics on the abovementioned outputs, a sensitivity analysis is carried out through the calculation of the Main Effect index (ME), utilizing a total of 110,160 parametric simulations. The optimal glazing configuration is determined for each case in terms of both energy efficiency and cost and general guidelines are provided for each examined climate. It was found that, for the case study, smart glazing configurations lead to 7-16% primary energy savings and reduce net present cost up to 18% compared to conventional state-of-the-art glazing. According to the sensitivity analysis, energy savings are higher for warmer climates, lower overhang depths, higher Window-to-Wall Ratios (WWR) and office uses. Net present cost is mostly affected by the smart glazing configuration and the building's location. In most cases, the optimal glazing configuration regarding energy efficiency is a quadruple electrochromic glazing with krypton, while the most cost-effective configuration is a triple electrochromic glazing with argon.