Toward Net Zero Energy Buildings with Energy Harvesting Electrochromic Windows (EH-ECWs)

Recent developments in material science offer the potential for energy harvesting electrochromic (EH-ECW) windows. This technology offers a glazing system that will enable switching of visible light transmission (Tvis) and solar heat gain coefficient (SHGC) to admit heat and light relative to interior comfort requirements as well as allowing for the conversion of unwanted solar radiation through windows into electric current while in a darkened state. Concurrently, efforts have been underway to develop net-zero energy buildings through a combination of climate-responsive design, efficient systems, and on-site renewable energy generation. EH-ECWs provide the potential to amplify this process by simultaneously reducing building energy demand while increasing on-site energy production. This paper presents simulation-based research to identify zone-level and whole building energy production and consumption in a medium-sized office building based on three primary variables: (1) climate, (2) orientation, and (3) window-to-wall ratio. It proposes optimization curves for energy performance based on zone-level aggregate heating cooling and lighting coupled with the resulting energy harvesting potential. Furthermore, we include a discussion of perimeter-zone versus core zone energy performance with design implications for building massing and surface-to-volume ratios.