Modeling of optical and energy performance of tungsten-oxide-based electrochromic windows including their intermediate states

TitleModeling of optical and energy performance of tungsten-oxide-based electrochromic windows including their intermediate states
Publication TypeJournal Article
Year of Publication2013
AuthorsSunnie H.N. Lim, Jan Isidorsson, Lizhong Sun, B. Leo Kwak, André Anders
JournalSolar Energy Materials and Solar Cells
Volume108
Pagination129 - 135
Date Published1/2013
ISSN09270248
KeywordsElectrochromic windows, Energy efficient window modeling, Energy simulation, Smart windows
Abstract

Tungsten-oxide-based electrochromic (EC) windows are currently the most robust and matured dynamic windows where the transmittance of visual light and near-infrared radiation can be controlled by a small applied voltage. In its standard application, the window is commonly either in its clear or colored state. In this contribution, we study the optical and energy performance of such window in the fully bleached and fully colored state as well as when it is kept in intermediate states. Different configurations in terms of placement of the EC layer stack and possible additional low-emissivity (low-E) coating within the insulated glass unit are considered. Using optical data and software tools we find that even a small coloration has a significant effect on the energy performance because the solar heat gain coefficient is readily reduced by the absorption of the EC layer stack. We compare the performance of the EC windows to commercially available solar-control (spectrally selective) low-E windows.

DOI10.1016/j.solmat.2012.09.010
Short TitleSolar Energy Materials and Solar Cells