@article {55433, title = {Lighting energy savings potential of split-pane electrochromic windows controlled for daylighting with visual comfort}, journal = {Energy and Buildings}, volume = {61}, year = {2013}, month = {06/2013}, pages = {8-20}, abstract = {

A simulation study was conducted to evaluate lighting energy savings of split-pane electrochromic (EC) windows controlled to satisfy key visual comfort parameters. Using the Radiance lighting simulation software, interior illuminance and luminance levels were computed for a south-facing private office illuminated by a window split into two independently-controlled EC panes. The transmittance of these was optimized hourly for a workplane illuminance target while meeting visual comfort constraints, using a least-squares algorithm with linear inequality constraints. Blinds were successively deployed until visual comfort criteria were satisfied. The energy performance of electrochromics proved to be highly dependent on how blinds were controlled. With hourly blind position adjustments, electrochromics showed significantly higher (62\% and 53\%, respectively without and with overhang)lighting energy consumption than clear glass. With a control algorithm designed to better approximate realistic manual control by an occupant, electrochromics achieved significant savings (48\% and 37\%, respectively without and with overhang). In all cases, energy consumption decreased when the workplace illuminance target was increased. In addition, the fraction of time during which the occupant had an unobstructed view of the outside was significantly greater with electrochromics: 10 months out of the year versus a handful of days for the reference case.

}, keywords = {Building energy-efficiency, Control optimization, daylighting, Electrochromic windows}, doi = {10.1016/j.enbuild.2012.10.057}, author = {Luis L. Fernandes and Eleanor S. Lee and Gregory J. Ward} } @article {58219, title = {Light-scattering properties of a Venetian blind slat used for daylighting applications}, journal = {Solar Energy}, volume = {84}, year = {2010}, month = {12/2010}, pages = {2103 - 2111}, abstract = {

The low cost, simplicity, and aesthetic appearance of external and internal shading devices, make them commonly used for daylighting and glare-control applications. Shading devices, such as Venetian blinds, screens, and roller shades, generally exhibit light scattering and/or light redirecting properties. This requires the bi-directional scattering distribution function (BSDF) of the material to be known in order to accurately predict the daylight distribution and energy flow through the fenestration system. Acquiring the complete BSDF is not a straightforward task, and to complete the process it is often required that a model is used to complement the measured data. In this project, a Venetian blind slat with a white top surface and a brushed aluminum bottom surface was optically characterized. A goniophotometer and an integrating sphere spectrophotometer were used to determine the angle resolved and hemispherical reflectance of the sample, respectively. The acquired data were fitted to a scattering model providing one Lambertian and one angle dependent description of the surface properties. These were used in combination with raytracing to obtain the complete BSDFs of the Venetian blind system.

}, keywords = {ABg-model, BSDF, Raytracing, Venetian blinds}, issn = {0038092X}, doi = {10.1016/j.solener.2010.09.005}, author = {Annica M. Nilsson and Jacob C. Jonsson} } @conference {12020, title = {Light-scattering properties of a woven shade-screen material used for daylighting and solar heat-gain control}, booktitle = {SPIE Optics+Photonics}, year = {2008}, month = {08/2008}, address = {San Diego, CA}, abstract = {

Shade-screens are widely used in commercial buildings as a way to limit the amount of direct sunlight that can disturb people in the building. The shade screens also reduce the solar heat-gain through glazing the system. Modern energy and daylighting analysis software such as EnergyPlus and Radiance require complete scattering properties of the scattering materials in the system.

In this paper a shade screen used in the LBNL daylighting testbed is characterized using a photogoniometer and a normal angle of incidence integrating sphere. The data is used to create a complete bi-directional scattering distribution function (BDSF) that used in simulation programs.

The resulting BDSF is compared to a model{\textquoteright}s BDSF, both directly and by calculating the solar heat-gain coefficient for a dual-pane system using Window 6.

}, author = {Jacob C. Jonsson and Eleanor S. Lee and Michael D. Rubin} } @article {12037, title = {A low-energy linear oxygen plasma source}, journal = {Review of Scientific Instruments}, volume = {78}, year = {2007}, month = {04/2007}, chapter = {043104}, abstract = {

A new version of a constricted plasma source is described, characterized by all metal-ceramic construction, a linear slit exit of 180 mm length, and cw operation typically 50 kHz at an average power of 1.5 kW. The plasma source is here operated with oxygen gas, producing streaming plasma that contains mainly positive molecular and atomic ions, and to a much lesser degree, negative ions. The maximum total ion current obtained was about 0.5 A. The fraction of atomic ions reached more than 10\% of all ions when the flow rate was less then 10 SCCM O2, corresponding to a chamber pressure of about 0.5 Pa for the selected pumping speed. The energy distribution functions of the different ion species were measured with a combined mass spectrometer and energy analyzer. The time-averaged distribution functions were broad and ranged from about 30 to 90 eV at 200 kHz and higher frequencies, while they were only several eV broad at 50 kHz and lower frequencies, with the maximum located at about 40 eV for the grounded anode case. This maximum was shifted down to about 7 eV when the anode was floating, indicating the important role of the plasma potential for the ion energy for a given substrate potential. The source could be scaled to greater length and may be useful for functionalization of surfaces and plasma-assisted deposition of compound films.

}, keywords = {atomic and molecular ions, Constricted plasma source, ion energy distribution functions, oxygen plasma}, author = {Andr{\'e} Anders and Georgy Yu Yushkov} } @article {12036, title = {Low-Cost Networking for Dynamic Window Systems}, journal = {Energy and Buildings}, volume = {36}, number = {6}, year = {2004}, pages = {503-513}, abstract = {

A low-cost building communications network is needed that would allow individual window and lighting loads to be controlled fromsan existing enterprise LAN network. This building communications network concept, which we term Integrated Building EnvironmentalsCommunications System (IBECSTM), would enable both occupant-based and building-wide control of individual window, lighting, andssensor devices. IBECS can reduce the cost of systemic control because it allows a drastic cost reduction in per point networking costs. This kind of effort is needed to encourage the control industry to make the commitment to build this technology and to demonstratesto prospective customers that this breakthrough approach to more comprehensive systemic control will provide them with high-quality,sconvenient control while saving them money.

The development and demonstration of network interfaces to DC- and AC-motorized shades and to an electrochromic window aresdescribed. The network interfaces enable one to control and monitor the condition of these fenestration appliances from a variety of sources,sincluding a user?s personal computer. By creating a functional specification for an IBECS network interface and testing a prototype, thesability to construct such an interface was demonstrated and the cost-effective price per point better understood. The network interfacesswere demonstrated to be reliable in a full-scale test of three DC-motorized Venetian blinds in an open-plan office over 2 years and in limitedsbench-scale tests of an electrochromic window.

}, author = {Eleanor S. Lee and Dennis L. DiBartolomeo and Francis M. Rubinstein and Stephen E. Selkowitz} } @conference {12035, title = {Lithium-Based Electrochromic Mirrors}, booktitle = {203rd Meeting of the Electrochemical Society}, year = {2003}, month = {04/2003}, address = {Paris, France}, abstract = {

Antimony, antimony-copper, and antimony-silver thin films were prepared by DC magnetron sputtering on glass substrates. Their reflectance and transmittance in the visible range were measured before and after electrochemical lithiation. The mixed metal films exhibited larger changes in reflectance and small shifts in the optical absorption edge compared with pure antimony films. Electrochromic cycling speed and stability of the Sb-Li system were improved by the addition of copper and silver.

}, author = {Thomas J. Richardson and Jonathan L. Slack} } @conference {12032, title = {Liquid Phase Deposition of Electrochromic Thin Films}, booktitle = {Electrochimica Acta}, volume = {46}, year = {2000}, month = {08/2000}, pages = {2119-2123}, address = {Uppsala, Sweden}, abstract = {

Thin films of titanium, zirconium and nickel oxides were deposited on conductive SnO2:F glass substrates by immersion in aqueous solutions. The films are transparent, conformal, of uniform thickness and appearance, and adhere strongly to the substrates. On electrochemical cycling, TiO2, mixed TiO2-ZrO2, and NiOx films exhibited stable electrochromism with high coloration efficiencies. These nickel oxide films were particularly stable compared with films prepared by other non-vacuum techniques. The method is simple, inexpensive, energy efficient, and readily scalable to larger substrates.

}, author = {Thomas J. Richardson and Michael D. Rubin} } @conference {12011, title = {Large Area Glare Sources and Their Effect on Discomfort and Visual Performance at Computer Workstations}, booktitle = {1992 IEEE Industry Applications Society Annual Meeting}, year = {1992}, month = {10/1992}, address = {Houston, TX}, abstract = {

This paper studies the effects of a large area light source of variable but uniform luminance surrounding a video display terminal (VDT) on the perceived glare discomfort and visual performance of computer operators. A set of criteria was established for rating the discomfort from glare as either intolerable, disturbing, noticeable, or imperceptible. Source luminance adjustments by means of a variable transformer to match the subjective glare criteria, as well as ratings of preselected lighting conditions on a visual analog scale with the same criteria, were used to determine comfortable lighting conditions. Results from the experiment indicate that subjects reliably selected a preferred lighting condition at any time when asked to adjust the luminance to produce optimum visual comfort. There was considerable between-subject variation in the range of luminances over which the surround field was neither noticeably too dim nor noticeably too bright. Comfortable luminance ranges also varied with initial presentation luminances immediately preceding the adjustment. Subjects preferred higher luminances following high initial presentation luminances. Performance speed at a difficult letter-counting task suggests that visual performance was slightly impaired by the presence of glare discomfort. Counting errors also occurred slightly more frequently under higher surround source luminances. There was a tendency for subjects to become more susceptible to glare over the course of the experiment.

}, author = {Werner K.E. Osterhaus and Ian L. Bailey} }