TY - RPRT T1 - Advancement of Electrochromic Windows Y1 - 2006/04// A1 - Eleanor S. Lee A1 - Stephen E. Selkowitz A1 - Robert D. Clear A1 - Dennis L. DiBartolomeo A1 - Joseph H. Klems A1 - Luis L. Fernandes A1 - Gregory J. Ward A1 - Vorapat Inkarojrit A1 - Mehry Yazdanian KW - commercial buildings KW - daylight KW - daylighting controls KW - Electrochromic windows KW - energy efficiency KW - human factors KW - peak demand KW - switchable windows KW - visual comfort AB - 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. U1 -

Windows and Daylighting Group

U2 - LBNL-59821 ER - TY - RPRT T1 - A Design Guide for Early-Market Electrochromic Windows Y1 - 2006/ A1 - Eleanor S. Lee A1 - Stephen E. Selkowitz A1 - Robert D. Clear A1 - Dennis L. DiBartolomeo A1 - Joseph H. Klems A1 - Luis L. Fernandes A1 - Gregory J. Ward A1 - Vorapat Inkarojrit A1 - Mehry Yazdanian AB - 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. U1 -

Windows and Daylighting Group

U2 - LBNL-59950 ER - TY - JOUR T1 - Subject Response to Electrochromic Windows JF - Energy and Buildings Y1 - 2006/07// SP - 758 EP - 779 A1 - Robert D. Clear A1 - Vorapat Inkarojrit A1 - Eleanor S. Lee KW - Electrochromic windows KW - energy use KW - Subjective response KW - Venetian blind use AB - 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. VL - 38 IS - 7 U1 -

Windows and Daylighting Group

U2 - LBNL-57125 DO - 10.1016/j.enbuild.2006.03.011 ER - TY - THES T1 - Balancing comfort: occupants' control of window blinds in private offices T2 - Architecture Y1 - 2005/ SP - 281 A1 - Vorapat Inkarojrit AB - 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. JF - Architecture PB - University of California, Berkeley CY - Berkeley UR - http://escholarship.org/uc/item/3rd2f2bg ER - TY - RPRT T1 - Daylighting the New York Times Headquarters Building: Final Report Y1 - 2005/06// A1 - Eleanor S. Lee A1 - Stephen E. Selkowitz A1 - Glenn D. Hughes A1 - Robert D. Clear A1 - Gregory J. Ward A1 - John Mardaljevic A1 - Judy Lai A1 - Mehlika Inanici A1 - Vorapat Inkarojrit KW - automated daylighting controls KW - automated window shades KW - daylighting KW - energy-efficiency KW - visual comfort AB - 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. U2 - LBNL-57602 ER - TY - ABST T1 - Analysis of visual comfort using high-dynamic-range luminance images Y1 - 2004/ A1 - Vorapat Inkarojrit ER - TY - RPRT T1 - Energy Performance Analysis of Electrochromic Windows in New York Commercial Office Buildings Y1 - 2002/11// A1 - Eleanor S. Lee A1 - L. Zhou A1 - Mehry Yazdanian A1 - Vorapat Inkarojrit A1 - Jonathan L. Slack A1 - Michael D. Rubin A1 - Stephen E. Selkowitz AB - 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. U1 -

Windows and Daylighting Group

U2 - LBNL-50096 ER - TY - RPRT T1 - High-Performance Commercial Building Façades Y1 - 2002/ A1 - Eleanor S. Lee A1 - Stephen E. Selkowitz A1 - Christian Kohler A1 - Vladimir Bazjanac A1 - Vorapat Inkarojrit AB - 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. U1 -

Windows and Daylighting Group

U2 - LBNL-50502 ER -