@article {31851, title = {Split-pane electrochromic window control based on an embedded photometric device with real-time daylighting computing}, journal = {Building and Environment}, volume = {161}, year = {2019}, month = {08/2019}, pages = {106229}, abstract = {

Well-designed electrochromic (EC) glazing control can improve the energy performance of buildings and visual comfort of occupants in highly glazed buildings. This paper designed and demonstrated a compact integrated EC glazing automation system to control tint states of a split-pane EC window according to variations of sky conditions. The control is based on monitoring the luminance distribution of the sky and real-time lighting computation for a building interior, using an embedded photometric device (EPD). It optimizes tint states of EC glazing to offer sufficient daylight provision and temper discomfort glare for occupants, which potentially mitigates excessive solar heat gain. {\textquoteright}In-situ{\textquoteright} experiments were conducted in a full-scale testbed to demonstrate the daylighting performance under various sky conditions. Experimental results showed 83\% of the working time for work-plane illuminance (WPI) and 95\% of the time for daylight glare probability (DGP) were constrained in comfort range (WPI[500, 2000] lux, DGP\ <=\ 0.35) by the automated EC glazing (controlled by EPD) under clear skies; 68\% of the time for WPI and 94\% of the time for DGP in confined range under clear skies with thin clouds; 62\% of the time for WPI and 85\% of the time for DGP in confined range under partly cloudy skies.

}, keywords = {daylighting, electrochromic, Embedded Controller, HDR, windows}, issn = {03601323}, doi = {10.1016/j.buildenv.2019.106229}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0360132319304391}, author = {Yujie Wu and Taoning Wang and Eleanor S. Lee and J{\'e}r{\^o}me H. K{\"a}mpf and Jean-Louis Scartezzini} } @techreport {60935, title = {A Pilot Demonstration of Electrochromic and Thermochromic Windows in the Denver Federal Center, Building 41, Denver, Colorado}, year = {2013}, note = {

Completed September 30, 2012, released March 30, 2014.

}, month = {07/2013}, abstract = {

Chromogenic glazing materials are emerging technologies that tint reversibly from a clear to dark tinted state either passively in response to environmental conditions or actively in response to a command from a switch or building automation system. Switchable coatings on glass manage solar radiation and visible light while enabling unobstructed views to the outdoors. Building energy simulations estimate that actively controlled, near-term chromogenic glazings can reduce perimeter zone heating, ventilation, and air- conditioning (HVAC) and lighting energy use by 10-20\% and reduce peak electricity demand by 20-30\%, achieving energy use levels that are lower than an opaque, insulated wall.

This project demonstrates the use of two types of chromogenic windows: thermochromic and electrochromic windows. By 2013, these windows will begin production in the U.S. by multiple vendors at high-volume manufacturing plants, enabling lower cost and larger area window products to be specified. Both technologies are in the late R\&D stage of development, where cost reductions and performance improvements are underway. Electrochromic windows have been installed in numerous buildings over the past four years, but monitored energy-efficiency performance has been independently evaluated in very limited applications. Thermochromic windows have been installed in one other building with an independent evaluation, but results have not yet been made public.

}, keywords = {building controls, daylighting, Demand Side Management, electrochromic, energy-efficiency, Smart windows, switchable windows, Thermochromic, Window}, url = {http://gsa.gov/portal/content/187967}, author = {Eleanor S. Lee and Luis L. Fernandes and Howdy Goudey and Jacob C. Jonsson and Dragan C. Curcija and Xiufeng Pang and Dennis L. DiBartolomeo and Sabine Hoffmann} } @conference {11778, title = {Effective Medium Approximation of the Optical properties of electrochromic cerium-titanium oxide compounds}, booktitle = {SPIE Proceedings}, volume = {3138}, year = {1997}, month = {07/1997}, pages = {19-Sep}, address = {San Diego, CA}, abstract = {

Cerium titanium oxide samples derived from a solution have been compared against sputtered films over a wide range of different compositions. X-ray diffraction was used to investigate the structural properties of the compound material existing in a two-phase mixture MAO2-MBO2. The optical properties were evaluated over the whole solar spectrum by variable angle spectroscopic ellipsometry combined with spectrophutometry. The spectral complex refractive index was determined for CeO2 and TiO2, as well as for their compounds. To reduce the large number of permutations in composition of multi-component oxides it would be useful to be able to predict the properties of the mixtures from the pure oxide components. Therefore these results were compared to those obtained by effective medium theory utilizing the optical constants of CeO2 and TiO2. In order to investigate the performance as passive counter-electrode in Li+ based electrochromic devices the films were tested by cyclic voltammetry with in-situ transmission control. Chemical composition was measured by Rutherford backscattering spectrometry. Surface morphology was analyzed by atomic force microscopy.

}, keywords = {cerium titanium oxide, effective medium theory, electrochromic, optical constants}, author = {Klaus von Rottkay and Thomas J. Richardson and Michael D. Rubin and Jonathan L. Slack} } @article {12146, title = {Optical Indices of Electrochromic Tungsten Oxide}, journal = {Thin Solid Films}, volume = {306}, number = {1}, year = {1996}, month = {08/1997}, pages = {10-16}, chapter = {10}, abstract = {

Tungsten trioxide (WO3) is the most widely used material for the active layer of electrochromic devices. Knowledge of the complex refractive index over the range of coloration states is required for device design. Optical constants of WO3 over the whole solar spectrum were determined as a function of injected charge. Films of WO3 were prepared by electron-beam evaporation, then colored in several steps by reduction with lithium (Li) up to 68 mC cm-2 {\textmu}m-1 injected charge. Measurements included variable-angle spectroscopic ellipsometry and spectroscopic transmittance and reflectance at normal incidence. Analysis was complicated by the fact that a transparent-conducting layer of indium tin oxide (ITO) was required to perform lithiation. Optical indices of the glass substrate and ITO transparent conductor were determined separately and then fixed in the model. The indices of WO3 could then be extracted from measurements on the complete structure. A parametric dispersion model corresponding to Gaussian broadening of the oscillators was used to represent the dielectric response of WO3.

}, keywords = {Colored state, Complex refractive index, electrochromic, tungsten oxide}, doi = {10.1016/S0040-6090(97)00254-X}, author = {Klaus von Rottkay and Michael D. Rubin and Shi-Jie Wen} }