01830nas a2200241 4500008003900000022001300039245013000052210006900182260001100251300001400262490000800276520103900284653002701323653003701350653002201387653001801409100002201427700002001449700001701469700001401486700001901500856006901519 2013 d a0927024800aModeling of optical and energy performance of tungsten-oxide-based electrochromic windows including their intermediate states0 aModeling of optical and energy performance of tungstenoxidebased c1/2013 a129 - 1350 v1083 a

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.

10aElectrochromic windows10aEnergy efficient window modeling10aEnergy simulation10aSmart windows1 aLim, Sunnie, H.N.1 aIsidorsson, Jan1 aSun, Lizhong1 aKwak, Leo1 aAnders, André uhttps://facades.lbl.gov/publications/modeling-optical-and-energy01663nas a2200325 4500008004100000024002100041245004200062210004200104260001200146520070300158653002500861653001300886653002500899653002700924653002200951653001800973653001600991653002301007653001901030100002101049700002701070700002201097700002901119700002201148700002401170700002201194700002401216700002101240856007601261 2006 eng d aCEC-500-2006-05200aAdvancement of Electrochromic Windows0 aAdvancement of Electrochromic Windows c04/20063 a

This guide provides consumer-oriented information about switchable electrochromic (EC) windows. Electrochromic windows change tint with a small applied voltage, providing building owners and occupants with the option to have clear or tinted windows at any time, irrespective of whether it's sunny or cloudy. EC windows can be manually or automatically controlled based on daylight, solar heat gain, glare, view, energy-efficiency, peak electricity demand response, or other criteria. Window controls can be integrated with other building systems, such as lighting and heating/cooling mechanical systems, to optimize interior environmental conditions, occupant comfort, and energy-efficiency.

10acommercial buildings10adaylight10adaylighting controls10aElectrochromic windows10aenergy efficiency10ahuman factors10apeak demand10aswitchable windows10avisual comfort1 aLee, Eleanor, S.1 aSelkowitz, Stephen, E.1 aClear, Robert, D.1 aDiBartolomeo, Dennis, L.1 aKlems, Joseph, H.1 aFernandes, Luis, L.1 aWard, Gregory, J.1 aInkarojrit, Vorapat1 aYazdanian, Mehry uhttps://facades.lbl.gov/publications/advancement-electrochromic-windows02135nas a2200205 4500008004100000050001500041245005900056210005600115520147900171100002101650700002701671700002201698700002901720700002201749700002401771700002201795700002401817700002101841856006701862 2006 eng d aLBNL-5995000aA Design Guide for Early-Market Electrochromic Windows0 aDesign Guide for EarlyMarket Electrochromic Windows3 a

Switchable variable-tint electrochromic windows preserve the view out while modulating transmitted light, glare, and solar heat gains and can reduce energy use and peak demand. To provide designers objective information on the risks and benefits of this technology, this study offers data from simulations, laboratory tests, and a 2.5-year field test of prototype large-area electrochromic windows evaluated under outdoor sun and sky conditions. The study characterized the prototypes in terms of transmittance range, coloring uniformity, switching speed, and control accuracy. It also integrated the windows with a daylighting control system and then used sensors and algorithms to balance energy efficiency and visual comfort, demonstrating the importance of intelligent design and control strategies to provide the best performance. Compared to an efficient low-e window with the same daylighting control system, the electrochromic window showed annual peak cooling load reductions from control of solar heat gains of 19-26% and lighting energy use savings of 48-67% when controlled for visual comfort. Subjects strongly preferred the electrochromic window over the reference window, with preferences related to perceived reductions in glare, reflections on the computer monitor, and window luminance. The EC windows provide provided the benefit of greater access to view year-round. Though not definitive, findings can be of great value to building professionals.

1 aLee, Eleanor, S.1 aSelkowitz, Stephen, E.1 aClear, Robert, D.1 aDiBartolomeo, Dennis, L.1 aKlems, Joseph, H.1 aFernandes, Luis, L.1 aWard, Gregory, J.1 aInkarojrit, Vorapat1 aYazdanian, Mehry uhttps://facades.lbl.gov/publications/design-guide-early-market01267nas a2200205 4500008004100000245004700041210004700088260001200135300001200147490000700159520066600166653002700832653001500859653002400874653002300898100002200921700002400943700002100967856007300988 2006 eng d00aSubject Response to Electrochromic Windows0 aSubject Response to Electrochromic Windows c07/2006 a758-7790 v383 a

Forty-three subjects worked in a private office with switchable electrochromic windows, manually-operated Venetian blinds, and dimmable fluorescent lights. The electrochromic window had a visible transmittance range of approximately 3-60%. Analysis of subject responses and physical data collected during the work sessions showed that the electrochromic windows reduced the incidence of glare compared to working under a fixed transmittance (60%) condition. Subjects used the Venetian blinds less often and preferred the variable transmittance condition, but used slightly more electric lighting with it than they did when window transmittance was fixed.

10aElectrochromic windows10aenergy use10aSubjective response10aVenetian blind use1 aClear, Robert, D.1 aInkarojrit, Vorapat1 aLee, Eleanor, S. uhttps://facades.lbl.gov/publications/subject-response-electrochromic01474nas a2200121 4500008003900000245007800039210006900117260004900186300000800235520104000243100002401283856004501307 2005 d00aBalancing comfort: occupants' control of window blinds in private offices0 aBalancing comfort occupants control of window blinds in private  aBerkeleybUniversity of California, Berkeley a2813 a

The goal of this study was to develop predictive models of window blind control that could be used as a function in energy simulation programs and provide the basis for the development of future automated shading systems. Toward this goal, a two-part study, consisting of a window blind usage survey and a field study, was conducted in Berkeley, California, USA, during a period spanning from the vernal equinox to window solstice. A total of one hundred and thirteen office building occupants participated in the survey. Twenty-five occupants participated in the field study, in which measurements of physical environmental conditions were cross-linked to the participants’ assessment of visual and thermal comfort sensations.

Results from the survey showed that the primary window blind closing reason was to reduce glare from sunlight and bright windows. For the field study, a total of thirteen predictive window blind control logistic models were derived using the Generalized Estimating Equations (GEE) technique.

1 aInkarojrit, Vorapat uhttp://escholarship.org/uc/item/3rd2f2bg02657nas a2200265 4500008003900000245007100039210006900110260001200179520181700191653003502008653002802043653001602071653002202087653001902109100002102128700002702149700002202176700002202198700002202220700002202242700001402264700002102278700002402299856006802323 2005 d00aDaylighting the New York Times Headquarters Building: Final Report0 aDaylighting the New York Times Headquarters Building Final Repor c06/20053 a

The technical energy-savings potential for smart integrated window-daylighting systems is excellent and can yield significant reductions in US commercial building energy use if adopted by a significant percentage of the market. However, conventional automated shades and daylighting controls have been commercially available for over two decades with less than 1-2% market penetration in the US. As with all innovations, the problem with accelerating market adoption is one of decreasing risk. As the building owner researches technology options, the usual questions surface that concern the purchase of any new product: how will it work for my application, are the vendor claims valid, what risks are incurred, and will the performance benefits be sustained over the life of the installation? In their effort to create an environment that "enhances the way we work" in their new 139 km2 (1.5 Mft2) headquarters building in downtown Manhattan, The New York Times employed a unique approach to create a competitive marketplace for daylighting systems. A monitored field test formed the strategic cornerstone for accelerating an industry response to the building owners' challenge to a sleepy market (i.e., US automated shading and daylighting control products have had few major technical advances over the past 10 years). Energy, control system, and environmental quality performance of commercially-available automated roller shade and daylighting control systems were evaluated. Procurement specifications were produced. Bids were received that met The Times cost-effective criteria. The Times will proceed with the use of these systems in their final building. Competitively-priced new products have been developed as a result of this research and are now available on the market.

10aautomated daylighting controls10aautomated window shades10adaylighting10aenergy-efficiency10avisual comfort1 aLee, Eleanor, S.1 aSelkowitz, Stephen, E.1 aHughes, Glenn, D.1 aClear, Robert, D.1 aWard, Gregory, J.1 aMardaljevic, John1 aLai, Judy1 aInanici, Mehlika1 aInkarojrit, Vorapat uhttps://facades.lbl.gov/publications/daylighting-new-york-times00369nas a2200085 4500008004100000245007300041210006900114100002400183856007600207 2004 eng d00aAnalysis of visual comfort using high-dynamic-range luminance images0 aAnalysis of visual comfort using highdynamicrange luminance imag1 aInkarojrit, Vorapat uhttps://facades.lbl.gov/publications/analysis-visual-comfort-using-high01165nas a2200121 4500008004100000050001500041245008200056210006900138520072800207100002100935700001600956856007100972 2004 eng d aLBNL-5754500aEvaluation of High Dynamic Range Photography as a Luminance Mapping Technique0 aEvaluation of High Dynamic Range Photography as a Luminance Mapp3 a

The potential, limitations, and applicability of the High Dynamic Range (HDR) photography technique is evaluated as a luminance mapping tool. Multiple exposure photographs of static scenes are taken with a Nikon 5400 digital camera to capture the wide luminance variation within the scenes. The camera response function is computationally derived using the Photosphere software, and is used to fuse the multiple photographs into HDR images. The vignetting effect and point spread function of the camera and lens system is determined. Laboratory and field studies have shown that the pixel values in the HDR photographs can correspond to the physical quantity of luminance with reasonable precision and repeatability.

1 aInanici, Mehlika1 aGalvin, Jim uhttps://facades.lbl.gov/publications/evaluation-high-dynamic-range02249nas a2200181 4500008004100000245009800041210006900139260001200208520162500220100002101845700001301866700002101879700002401900700002401924700002301948700002701971856006901998 2002 eng d00aEnergy Performance Analysis of Electrochromic Windows in New York Commercial Office Buildings0 aEnergy Performance Analysis of Electrochromic Windows in New Yor c11/20023 a

A DOE-2.1E energy simulation analysis of a switchable electrochromic (EC) glazing with daylighting controls has been conducted for prototypical office buildings in New York (NY). The modeling included four types of office buildings: "old" and "new" vintages and large (10,405 m2, 112,000 ft2) and small (502m2, 5400 ft2) buildings. Five commercially available, base case windows with and without interior shades were modeled. Window area varied from 0 to 60% of the exterior floor-to-floor wall area. The electric lighting had either no controls or continuous daylighting controls. The prototypes were modeled in New York City or Buffalo.

Energy performance ata are given for each of the four perimeter zones. Data are presented as a function of window-to-wall ratio in order to better understand the interactions between 1) electric lighting energy use and daylight admission and 2) solar heat gains and space-conditioning energy use. Maximum and minimum reductions in energy use between the EC glazing and all other base case conditions are also presented. Projected energy use reductions relative to typical specified NY office buildings are presented as an indication of the potential impacts EC glazings might have in retrofit and new construction.

The energy and demand reductions provided by EC glazings with daylighting controls relative to what is typically specified in office buildings in NY are quite substantial. EC glazings will also dampen fluctuations in interior daylight levels and window brightness, potentially increasing visual comfort.

1 aLee, Eleanor, S.1 aZhou, L.1 aYazdanian, Mehry1 aInkarojrit, Vorapat1 aSlack, Jonathan, L.1 aRubin, Michael, D.1 aSelkowitz, Stephen, E. uhttps://facades.lbl.gov/publications/energy-performance-analysis02180nas a2200157 4500008004100000050001500041245005000056210004900106520167200155100002101827700002701848700002201875700002301897700002401920856007801944 2002 eng d aLBNL-5050200aHigh-Performance Commercial Building Façades0 aHighPerformance Commercial Building Façades3 a

There is a significant and growing interest in the use of highly-glazed façades in commercial buildings. Large portions of the façade or even the entire façade are glazed with relatively high transmittance glazing systems, and typically with some form of sun control as well. With origins in Europe the trend is expanding to other regions, including the United States. A subset of these designs employ a second layer creating a double envelope system, which can then accommodate additional venting and ventilation practices. The stated rationale for use of the these design approaches varies but often includes a connection to occupant benefits as well as sustainable design associated with daylighting and energy savings. As with many architectural trends, understanding the reality of building performance in the field as compared to design intent is often difficult to ascertain. We have been particularly interested in this emerging trend because prior simulation studies have shown that it should be technically possible to produce an all-glass façade with excellent performance although it is not a simple challenge. The published solutions are varied enough and sufficiently complex that we undertook a year-long international review of advanced façades to better understand the capabilities and limitations of existing systems and the tools and processes used to create them. This is also intended to create a framework for addressing the missing tools, technologies, processes and data bases that will be needed to turn the promise of advanced façades into realities. This summary, available as a PDF file and a web site, reports those findings.

1 aLee, Eleanor, S.1 aSelkowitz, Stephen, E.1 aKohler, Christian1 aBazjanac, Vladimir1 aInkarojrit, Vorapat uhttps://facades.lbl.gov/publications/high-performance-commercial-building01800nas a2200169 4500008004100000050001500041245016500056210006900221300001400290490000700304520115200311100002001463700002501483700002301508700002301531856007601554 1998 eng d aLBNL-4182000aEllipsometry on Sputter Deposited Tin Oxide Films: Optical Constants Versus Stoichiometry Hydrogen Content, and Amount of Electrochemically Intercalated Lithium0 aEllipsometry on Sputter Deposited Tin Oxide Films Optical Consta a7734-77410 v373 a

Tin oxide thin films were deposited by reactive radio-frequency magnetron sputtering onto In2O3:Sn coated and bare glass substrates. Optical constants in the 300-2500 nm wavelength range were determined by a combination of variable-angle spectroscopic ellipsometry and spectrophotometric transmittance measurements. Surface roughness was modeled from optical measurements and compared with atomic-force microscopy. The two techniques gave consistent results. The fit between experimental optical data and model results could be significantly improved when it was assumed that the refractive index of the Sn oxide varied across the film thickness. Varying the oxygen partial pressure during deposition made it possible to obtain films whose complex refractive index changed at the transition from SnO to SnO2. An addition of hydrogen gas during sputtering led to lower optical constants in the full spectral range in connection with a blue shift of the band gap. Electrochemical intercalation of lithium ions into the Sn oxide films raised their refractive index and enhanced their refractive-index gradient.

1 aIsidorsson, Jan1 aGranqvist, Claes, G.1 avon Rottkay, Klaus1 aRubin, Michael, D. uhttps://facades.lbl.gov/publications/ellipsometry-sputter-deposited-tin