02807nas a2200253 4500008004100000022001300041245012200054210006900176260001200245300001100257490000800268520202500276653001602301653001902317653002402336653000802360653001202368100001402380700001802394700002102412700002502433700002802458856006702486 2019 eng d a0360132300aSplit-pane electrochromic window control based on an embedded photometric device with real-time daylighting computing0 aSplitpane electrochromic window control based on an embedded pho c08/2019 a1062290 v1613 a

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. ’In-situ’ 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.

10adaylighting10aelectrochromic10aEmbedded Controller10aHDR10awindows1 aWu, Yujie1 aWang, Taoning1 aLee, Eleanor, S.1 aKämpf, Jérôme, H.1 aScartezzini, Jean-Louis uhttps://linkinghub.elsevier.com/retrieve/pii/S036013231930439103134nas a2200241 4500008004100000022001300041245011500054210006900169260001200238300001400250490000800264520230200272653005802574653001602632653002102648653002102669653004902690653001302739100001802752700001802770700002102788856008302809 2018 eng d a0378778800aEfficient modeling of optically-complex, non-coplanar exterior shading: Validation of matrix algebraic methods0 aEfficient modeling of opticallycomplex noncoplanar exterior shad c09/2018 a464 - 4830 v1743 a

It has long been established that shading windows with overhangs, fins, and other types of non-coplanar systems (NCS) is one of the most effective ways of controlling solar heat gains in buildings because they intercept solar radiation prior to entry into the building. Designers however often specify non-opaque materials (e.g., louvers, fritted glass, expanded metal mesh) for these systems in order to admit daylight, reduce lighting energy use, and improve indoor environmental quality. Most simulation tools rely on geometric calculations and radiosity methods to model the solar heat gain impacts of NCS and cannot model optically-complex materials or geometries. For daylighting analysis, optically-complex NCS can be modeled using matrix algebraic methods, although time-efficient parametric analysis has not yet been implemented. Determining the best design and/or material for static or operable NCS that minimize cooling, heating, and lighting energy use and peak demand requires an iterative process. This study describes and validates a matrix algebraic method that enables parametric energy analysis of NCS. Such capabilities would be useful not only for design but also for development of prescriptive energy-efficiency standards, rating and labeling systems for commercial products, development of design guidelines, and development of more optimal NCS technologies.

A facade or "F" matrix, which maps the transfer of flux from the NCS to the surface of the window, is introduced and its use is explained. A field study was conducted in a full-scale outdoor testbed to measure the daylight performance of an operable drop-arm awning. Simulated data were compared to measured data in order to validate the models. Results demonstrated model accuracy: simulated workplane illuminance was within 11-13%, surface luminance was within 16-18%, and the daylight glare probability was within 6-9% of measured results. Methods used to achieve accurate results are discussed. Results of the validation of daylighting performance are applicable to solar heat gain performance. Since exterior shading can also significantly reduce peak demand, these models enable stakeholders to more accurately assess HVAC and lighting impacts in support of grid management and resiliency goals.

10abidirectional scattering distribution function (BSDF)10adaylighting10aexterior shading10asolar heat gains10avalidation; building energy simulation tools10awindows.1 aWang, Taoning1 aWard, Gregory1 aLee, Eleanor, S. uhttps://www.sciencedirect.com/science/article/pii/S0378778818302457?via%3Dihub03133nas a2200205 4500008003900000245010300039210006900142260001200211300001200223490000700235520243300242653001602675653002302691653004002714653002602754653003202780100002002812700002102832856007402853 2015 d00aMeasured daylighting potential of a static optical louver system under real sun and sky conditions0 aMeasured daylighting potential of a static optical louver system c10/2015 a347-3590 v923 a

By utilizing highly specular surfaces and engineered profile geometry, optical sunlight redirecting systems integrated into the overhead “clerestory” zone of the building facade present the potential to enlarge the daylighting zone by redirecting the luminous flux incident on the window deeper into the space than conventional shading systems. In addition, by developing system geometry to redirect daylight to specific zones within the space, optical light redirecting systems have the potential to avoid the glare conditions commonly produced by conventional facade shading systems that direct significant amounts of daylight below head height into the occupant's field of view. In this case study, side-by-side comparisons were made over solstice-to-solstice changes in sun and sky conditions between an optical louver system (OLS) and a conventional Venetian blind set at a horizontal slat angle and located inboard of a south-facing, small-area, clerestory window in a full-scale office testbed. Daylight autonomy (DA), window luminance, and ceiling luminance uniformity were used to assess performance. The performance of both systems was found to have significant seasonal variation, where performance under clear sky conditions improved as maximum solar altitude angles transitioned from solstice to equinox. Although the OLS produced fewer hours per day of DA on average than the Venetian blind, the OLS never exceeded the designated 2000 cd/m2 threshold for window glare. In contrast, the Venetian blind was found to exceed the visual discomfort threshold over a large fraction of the day during equinox conditions (from 40 to 64% of the test day between August 22 and October 12). Notably, these peak periods of visual discomfort occurred during the best periods of daylighting performance. Luminance uniformity was analyzed using calibrated high dynamic range luminance images. Under clear sky conditions, the OLS was found to increase the luminance of the ceiling as well as produce a more uniform distribution of luminance over the ceiling. Compared to conventional venetian blinds, the static optical sunlight redirecting system studied has the potential to significantly reduce the annual electrical lighting energy demand of a daylit space and improve the quality from the perspective of building occupants by consistently transmitting useful daylight while eliminating window glare.

10adaylighting10afield measurements10ahigh dynamic range luminance images10aoptical louver system10asunlight redirecting system1 aKonis, Kyle, S.1 aLee, Eleanor, S. uhttps://facades.lbl.gov/publications/measured-daylighting-potential-003492nas a2200253 4500008003900000245009000039210006900129260001200198300000700210520268100217653003002898653003102928653001602959653002002975653001202995100002403007700002103031700001903052700002303071700003103094700001803125700002103143856007403164 2014 d00aAngular selective window systems: Assessment of technical potential for energy saving0 aAngular selective window systems Assessment of technical potenti c01/2014 a363 a

Static angular selective shading systems block or filter direct sunlight and admit daylight within a specific range of incident solar angles. They can potentially deliver energy efficient performance within the typical 4.6-m (15-ft) deep perimeter zone of buildings when tailored to a specific façade orientation and latitude. The objective of this study is to quantify the technical potential of these systems to reduce energy use and peak demand in commercial buildings, specifically: a) achieve 30-50% reductions in perimeter zone energy use vs. ASHRAE 90.1-2004, b) constrain peak window loads to less than 43 W/m2-floor (4 W/ft2-floor), and c) to the extent possible, admit useful daylight in the perimeter zone without exceeding the peak solar load constraint. Three distinctly different commercial shading systems were evaluated: a micro-perforated screen, a tubular shading structure (double- and triple-paned configurations), and an expanded metal mesh. This evaluation was performed mainly through computer simulation for a multitude of scenarios, including multiple climates (Chicago, Illinois and Houston, Texas), window-to-wall ratios (0.15-0.60), building codes (ASHRAE 90.1-2004 and 2010) and lighting control configurations (with and without daylighting controls). Angular selective shading systems are optically complex and cannot be modeled accurately using conventional simulation tools, prompting the development of unique versions of the EnergyPlus, Radiance and Window simulation tools. Results show significant potential reductions in perimeter zone energy use, with the best commercially-available system reaching 28% and 47% savings, relative to ASHRAE 90.1- 2004 and respectively without and with daylighting controls, on south facades in Chicago with WWR=0.45, while constraining peak window heat gains to under 43 W/m2-floor, and enabling significant savings from daylighting controls. Results suggest that it is possible that existing systems can be improved to more consistently achieve 30-50% energy savings. Level of angular selectivity, spectral selectivity of low-e coatings and thermal conductance of the angle-selective layer were identified as critical factors for the performance of angular selective systems. Static, angular selective shading systems offer a potentially low-cost option to significantly reduce window heat gains and control glare from visibility of the sun orb, while permitting the admission of useful daylight and access to views to the outdoors. This type of system shows significant potential to contribute towards net-zero energy goals in both new and retrofit construction.

10aangular selective systems10aBuilding energy-efficiency10adaylighting10aShading Systems10awindows1 aFernandes, Luis, L.1 aLee, Eleanor, S.1 aMcNeil, Andrew1 aJonsson, Jacob, C.1 aNouidui, Thierry, Stephane1 aPang, Xiufeng1 aHoffmann, Sabine uhttps://facades.lbl.gov/publications/angular-selective-window-systems03205nas a2200421 4500008003900000245005700039210005600096260001200152520188100164653002202045653002502067653005202092653003702144653003302181653001602214653003302230653002002263653002102283653002002304653001802324653002502342653003002367653002202397653001202419653002902431653002302460653001902483653002402502653002502526100002102551700002202572700002402594700002102618700001902639700002902658700002202687856007402709 2014 d00aHigh Performance Building Façade Solutions-Phase II0 aHigh Performance Building Façade SolutionsPhase II c03/20143 a

The High Performance Building Façade Solutions–Phase II project was initiated through the California Energy Commission’s Public Interest Energy Research (PIER) program in July 2010 to support industry’s development and deployment of both incremental and breakthrough façade technologies in partnership with the U.S. Department of Energy (DOE). The objective of this three-year project was to develop, or support the development and deployment of, promising near-term and emerging zero net energy building façade technologies for solar control and daylighting, addressing two of the largest end uses in California commercial buildings: cooling and lighting. In partnership with industry (such as manufacturers), three classes of technologies were investigated: daylighting systems, angular-selective shading systems, and dynamic façade systems. Commercially available and emerging prototype technologies were developed and evaluated using laboratory tests. Simulations, full-scale outdoor tests in the Advanced Window Testbed, and demonstration projects quantified energy and peak electric demand reductions and occupant satisfaction, acceptance, and comfort associated with the resultant indoor environment. Several new technologies were developed using virtual prototyping tools. Integrated control systems were developed using model predictive controls. Simulation tools were developed to model operable complex fenestration systems such as shades and microprismatic films. A schematic design tool called COMFEN was developed to facilitate evaluation of these advanced technologies in the early design phase. All three classes of technologies resulted in significant reductions in perimeter zone energy use and peak electric demand, providing viable options that can support California’s long-term goal of achieving zero net energy use in the next decade.

10aautomated shading10abetween-pane shading10abidirectional scattering distribution functions10abuilding energy simulation tools10aComplex fenestration systems10adaylighting10adaylighting simulation tools10aelectrochromics10aexterior shading10agoniophotometer10alight shelves10amicroprismatic films10amodel predictive controls10amotorized shading10ashading10asolar-optical properties10aswitchable windows10athermochromics10avirtual prototyping10awindow heat transfer1 aLee, Eleanor, S.1 aCoffey, Brian, E.1 aFernandes, Luis, L.1 aHoffmann, Sabine1 aMcNeil, Andrew1 aThanachareonkit, Anothai1 aWard, Gregory, J. uhttps://facades.lbl.gov/publications/high-performance-building-fa-ade07924nas a2200265 4500008003900000245004800039210004800087260006500135520707300200653002507273653001607298653003807314653002107352653001507373653002207388653002507410653002107435653002007456653001907476100001907495700002207514700002107536700002707557856007407584 2014 d00aHigh Performance Building Mockup in FLEXLAB0 aHigh Performance Building Mockup in FLEXLAB aBerkeley, CAbLawrence Berkeley National Laboratoryc12/20143 a

Genentech has ambitious energy and indoor environmental quality performance goals for Building 35 (B35) being constructed by Webcor at the South San Francisco campus. Genentech and Webcor contracted with the Lawrence Berkeley National Laboratory (LBNL) to test building systems including lighting, lighting controls, shade fabric, and automated shading controls in LBNL's new FLEXLAB facility. The goal of the testing is to ensure that the systems installed in the new office building will function in a way that reduces energy consumption and provides a comfortable work environment for employees.

LBNL tested three facades of the new office building in the rotating FLEXLAB testbed: west, south and east. External shading, lighting, and internal shading control was configured for each orientation to replicate the conditions of B35. The three facades were each tested for one week three times between July and October 2014. Changes were made between each test to improve the performance of the systems.

Linear pendant LED light fixtures will illuminate the open office areas of the office building. These fixtures were installed in FLEXLAB. The wide spacing between rows of light fixtures results in a low lighting power density of 0.57 W/ft2 in the open office areas, while still meeting the average illuminance criteria of 300 lux (28 footcandles). A combination of the wide spacing and optics of the light fixture creates a nonuniform lighting pattern on the ceiling of the space. Changing to a diffuse lens on the uplight will help reduce abrupt changes in luminance on the ceiling but non-uniformity will persist due to the wide spacing.

The pendant light fixtures allow separate control of the downward and upward light. The lighting control design aims to enhance the quality of space by dimming upward light unison providing uniform patterns of electric light on the ceiling. The downward light of each fixture dims to provide just enough light to meet illuminance criteria below the fixture.

Webcor installed two lighting control systems manufactured by Enlighted and Encelium for testing in FLEXLAB. The Encelium system uses an open loop control architecture with a ceiling-mounted photosensor at each facade (inside of the automated shade). While there is greater variation in workplane illuminance provided by the Encelium system, the system is better able to control upward versus downward lighting and is able to control the lighting according to the lighting design intent. The architecture of the Encelium system offers more functional flexibility by allowing any input (sensors, switches etc.) or multiple inputs to affect any fixture.

The Enlighted control system uses closed loop architecture with two photosensors per fixture (one for upward light and one for downward light). The Enlighted system controlled the lights more precisely than the Encelium system to meet workplane illuminance requirements, however the upward versus downward light control did not behave according to the lighting design intent.

MechoSystems provided motorized window shades and automated control. The shades in each window had a different color fabric, one dark grey and one medium grey. Both shade fabrics were an open weave with 3% openness. Genentech selected the dark colored shade because it provides a better view of the exterior compared to the lighter colored shade. Anecdotal evidence suggests that some occupants may experience direct glare with 3% open fabric while other occupants will not experience glare under the same conditions. Visual discomfort during the worst case sunny winter condition was not evaluated. However, the east-facing orientation during the equinox period was exposed to low sun angles in the third test period so findings of just acceptable visual discomfort are expected to be similar to what might be experienced during the winter.

The shades operated as expected on sunny days (which was the predominant condition during the test period). The testing identified substantial potential energy savings for the lighting systems by stopping the shade above the sill, preventing the shade from completely covering the window and allowing the sun to shine deeper into the space through the bottom few inches of the window. On partly cloudy days, which occurred more frequently after our testing concluded, anecdotal evidence suggests that the shades could be raised more often. LBNL suggests that a second threshold be implemented which drops the shade partway to prevent direct glare from bright sun, but doesn't close the shade down to the height required to limit sunshine depth.

Thermal comfort analysis suggests that occupants seated near the shaded window will be comfortable around 80% of the time. The 20% of time where the observed conditions fall outside the ASHRAE Standard 55 are almost always due to occupants being cold in the morning. This discomfort is mostly driven by cold surrounding surfaces causing a low mean radiant temperature and overcooling from outside air during economizer mode. Only one thermal comfort station, located near the facade, was used for the experiment. Thermal comfort further from the facade is unknown but is likely to be better due to the increased distance from the relatively cold facade.

Visual comfort studies indicated that occupants could sit as close as 3.5 feet to the east and west facade and 2.5 feet to the south facade when facing parallel to the window. Occupants must sit further away from the window to be comfortable when facing the window directly. Occupants should be 3.5 feet away when facing the south facade, 4.5 feet away when facing the west facade and 5.5 feet away when facing the east facade. Thermal comfort studies show that sitting within 30 inches of the facade has a negligible effect on comfort ratings.

Daylighting controls reduced lighting energy use in FLEXLAB by 46% for east facade, 34% for south facade and 35% for west facade over 30 feet deep perimeter zone between 7 AM and 7 PM local time at autumn equinox. Occupancy controls will further reduce lighting energy use, though they were not implemented for the test due to the cell being tested unoccupied.

Genentech, Webcor, and the architectural and engineering team had access to the FLEXLAB during and for a month following the test period to observe, work, and discuss operational issues with employees and staff. The project team made their own qualitative observations about the space in terms of view, adequacy of lighting and daylight levels, color, furniture placement, etc. The project team worked collaboratively with the LBNL team to fine tune details of component design, control settings, troubleshooting, and operations. Because Genentech is introducing a new model for their work environment, a non-assigned workplace, there were detailed discussions on how to educate the occupants about the new technologies and their operational modes. Commissioning and tuning procedures were also discussed.

10acommercial buildings10adaylighting10aenergy management control systems10aexterior shading10afield test10alighting controls10amonitored evaluation10ashading controls10athermal comfort10avisual comfort1 aMcNeil, Andrew1 aKohler, Christian1 aLee, Eleanor, S.1 aSelkowitz, Stephen, E. uhttps://facades.lbl.gov/publications/high-performance-building-mockup02421nas a2200205 4500008003900000245011400039210006900153260001200222300001200234490000700246520171800253653003101971653001602002653002902018100002402047700002102071700002902092700001902121856007502140 2014 d00aMonitored lighting energy savings from dimmable lighting controls in The New York Times Headquarters Building0 aMonitored lighting energy savings from dimmable lighting control c01/2014 a498-5140 v683 a

Digital addressable, dimmable lighting controls were introduced to the US market in the early 2000s with the promise of facilitating capture of potential energy savings with greater flexibility over their historic, typically unreliable, analog counterpart. The New York Times Company installed this emerging technology, after having tested the system thoroughly prior to procurement, in their new building in New York, New York. Four years after full occupancy in 2007, the owner agreed to participate in a post-occupancy monitored evaluation of the dimmable lighting system to verify actual performance in the field. Annual lighting energy savings from daylighting, setpoint tuning and occupancy controls were determined for the daylit, open-plan office areas on three typical floors (6, 11, and 20th floors) of the 51-story high-rise tower. Energy savings were calculated from ballast control signal and occupancy data recorded by the manufacturer's lighting control system. The ballast data were calibrated with independent measurements of lighting energy consumption. Savings from dimming controls (daylighting and setpoint tuning) were 12.6 kWh/m2-yr (1.17 kWh/ft2-yr) for the daylit spaces on the three floors overall, or 20%, relative to ASHRAE 90.1-2007. Compared to the prescriptive code in effect at the time of the building's construction (ASHRAE 90.1-2001), savings were 21.0 kWh/m2-yr (1.95 kWh/ft2-yr) or 28%. Annual lighting energy use with all lighting control strategies was 33.9 kWh/m2-yr (3.15 kWh/ft2-yr) in the daylit, open plan zones on average for the three floors. A simple payback analysis was conducted.

10aBuilding energy-efficiency10adaylighting10alighting control systems1 aFernandes, Luis, L.1 aLee, Eleanor, S.1 aDiBartolomeo, Dennis, L.1 aMcNeil, Andrew uhttps://facades.lbl.gov/publications/monitored-lighting-energy-savings02440nas a2200157 4500008003900000245011900039210006900158520181800227653005202045653003202097653001602129653002502145100001902170700002102189856007202210 2013 d00aAnnual daylighting performance of a passive optical light shelf in sidelit perimeter zones of commercial buildings0 aAnnual daylighting performance of a passive optical light shelf 3 a

Sunlight redirecting systems have the potential to significantly offset electric lighting energy use in deep perimeter zones of buildings where the windows are subject to high daylight availability. New Radiance modeling tools have recently been developed and validated, enabling accurate and timely simulation analysis of the annual energy and comfort performance of these optically-complex, anisotropic systems. A parametric study was conducted using these tools to evaluate the performance of a commercially-available passive optical light shelf (OLS) in a 17.4 m deep (57 ft), south-facing open plan office zone in three climates. Daylighting efficiency, discomfort glare, and lighting energy savings with continuous dimming and bi-level switching controls were determined at varying depths within the zone. The OLS decreased lighting energy use significantly throughout the depth of the space and achieved these savings with minimal discomfort glare in the area near the window. Annual lighting energy use intensity was reduced to 1.71-1.82 kWh/ft2-yr (22-27%) over the full depth of the perimeter zone across the three climates modeled (Phoenix, Washington DC, and Minneapolis) compared to a non-daylit zone at 2.34 kWh/ft2-yr. There was a greater occurrence of discomfort glare (3-7% during daytime work hours) if the occupant was in a seated view position looking at the window from the back of the room. The system is passive, needing no adjustment during the day and over the seasons and can be used as a retrofit measure in existing buildings. These results are encouraging and demonstrate how the primary daylit sidelit area can be extended well beyond the defined limits provided by the newly adopted ASHRAE 90.1-2010 code (i.e., 1.0 times the head height of the window).

10abidirectional scattering distribution functions10abuildings energy efficiency10adaylighting10aRadiance simulations1 aMcNeil, Andrew1 aLee, Eleanor, S. uhttps://facades.lbl.gov/publications/annual-daylighting-performance02991nas a2200217 4500008003900000245010400039210006900143260004200212300001000254490000700264520225800271653003202529653001602561653002402577653001902601653001202620100002902632700002102661700001902682856007202701 2013 d00aEmpirical Assessment of a Prismatic Daylight-Redirecting Window Film in a Full-Scale Office Testbed0 aEmpirical Assessment of a Prismatic DaylightRedirecting Window F aHuntington Beach, Californiac10/2013 a19-450 v103 a

Daylight redirecting systems with vertical windows have the potential to offset lighting energy use in deep perimeter zones. Microstructured prismatic window films can be manufactured using low-cost, roll-to-roll fabrication methods and adhered to the inside surface of existing windows as a retrofit measure or installed as a replacement insulating glass unit in the clerestory portion of the window wall. A clear film patterned with linear, 50-250 micrometer high, four-sided asymmetrical prisms was fabricated and installed in the south-facing, clerestory low-e, clear glazed windows of a full-scale testbed facility. Views through the film were distorted. The film was evaluated in a sunny climate over a two-year period to gauge daylighting and visual comfort performance. The daylighting aperture was small (window-to-wall ratio of 0.18) and the lower windows were blocked off to isolate the evaluation to the window film. Workplane illuminance measurements were made in the 4.6 m (15 ft) deep room furnished as a private office. Analysis of discomfort glare was conducted using high dynamic range imaging coupled with the evalglare software tool, which computes the daylight glare= probability and other metrics used to evaluate visual discomfort.

The window film was found to result in perceptible levels of discomfort glare on clear sunny days from the most conservative view point in the rear of the room looking toward the window. Daylight illuminance levels at the rear of the room were significantly increased above the reference window condition, which was defined as the same glazed clerestory window but with an interior Venetian blind (slat angle set to the cut-off angle), for the equinox to winter solstice period on clear sunny days. For partly cloudy and overcast sky conditions, daylight levels were improved slightly. To reduce glare, the daylighting film was coupled with a diffusing film in an insulating glazing unit. The diffusing film retained the directionality of the redirected light= spreading it within a small range of outgoing angles. This solution was found to reduce glare to imperceptible levels while retaining for the most part the illuminance levels achieved solely by the daylighting film.

10abuildings energy efficiency10adaylighting10amicrostructure film10aprismatic film10awindows1 aThanachareonkit, Anothai1 aLee, Eleanor, S.1 aMcNeil, Andrew uhttps://facades.lbl.gov/publications/empirical-assessment-prismatic02177nas a2200205 4500008003900000245012200039210006900161260001200230300000900242490000700251520147200258653003101730653002501761653001601786653002701802100002401829700002101853700002201874856007501896 2013 d00aLighting energy savings potential of split-pane electrochromic windows controlled for daylighting with visual comfort0 aLighting energy savings potential of splitpane electrochromic wi c06/2013 a8-200 v613 a

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.

10aBuilding energy-efficiency10aControl optimization10adaylighting10aElectrochromic windows1 aFernandes, Luis, L.1 aLee, Eleanor, S.1 aWard, Gregory, J. uhttps://facades.lbl.gov/publications/lighting-energy-savings-potential02423nas a2200301 4500008003900000245013000039210006900169260001200238520147600250653002201726653001601748653002701764653001901791653002201810653001801832653002301850653001801873653001101891100002101902700002401923700001801947700002301965700002401988700001802012700002902030700002102059856004102080 2013 d00aA Pilot Demonstration of Electrochromic and Thermochromic Windows in the Denver Federal Center, Building 41, Denver, Colorado0 aPilot Demonstration of Electrochromic and Thermochromic Windows  c07/20133 a

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.

10abuilding controls10adaylighting10aDemand Side Management10aelectrochromic10aenergy-efficiency10aSmart windows10aswitchable windows10aThermochromic10aWindow1 aLee, Eleanor, S.1 aFernandes, Luis, L.1 aGoudey, Howdy1 aJonsson, Jacob, C.1 aCurcija, Dragan, C.1 aPang, Xiufeng1 aDiBartolomeo, Dennis, L.1 aHoffmann, Sabine uhttp://gsa.gov/portal/content/18796702476nas a2200325 4500008003900000245007600039210006900115260001200184300001200196490000700208520149100215653001701706653001601723653004601739653002201785653001001807653003301817653001301850653001201863100001901875700002301894700001901917700002201936700002801958700002101986700002102007700002102028700002402049856007702073 2013 d00aU.S. energy savings potential from dynamic daylighting control glazings0 aUS energy savings potential from dynamic daylighting control gla c11/2013 a415-4230 v663 a

Daylighting controls have the potential to reduce the substantial amount of electricity consumed for lighting in commercial buildings. Material science research is now pursuing the development of a dynamic prismatic optical element (dPOE) window coating that can continuously readjust incoming light to maximize the performance and energy savings available from daylighting controls. This study estimates the technical potential for energy savings available from vertical daylighting strategies and explores additional savings that may be available if current dPOE research culminates in a successful market-ready product. Radiance daylight simulations are conducted with a multi-shape prismatic window coating. Simulated lighting energy savings are then applied to perimeter floorspace estimates generated from U.S. commercial building stock data. Results indicate that fully functional dPOE coatings, when paired with conventional vertical daylight strategies, have the potential to reduce energy use associated with U.S. commercial electric lighting demand by as much as 930 TBtu. This reduction in electric lighting demand represents an approximately 85% increase in the energy savings estimated from implementing conventional vertical daylight strategies alone. Results presented in this study provide insight into energy and cost performance targets for dPOE coatings, which can help accelerate the development process and establish a successful new daylighting technology.

10aClerestories10adaylighting10aDynamic prismatic optical elements (dPOE)10aenergy efficiency10aGlare10aindoor environmental quality10aradiance10awindows1 aShehabi, Arman1 aDeForest, Nicholas1 aMcNeil, Andrew1 aMasanet, Eric, R.1 aGreenblatt, Jeffery, B.1 aLee, Eleanor, S.1 aMasson, Georgeta1 aHelms, Brett, A.1 aMilliron, Delia, J. uhttps://facades.lbl.gov/publications/us-energy-savings-potential-dynamic02197nas a2200229 4500008003900000245013800039210006900177260001200246300001200258490000700270520138900277653005201666653003301718653001601751653002001767100001901787700002301806700002101829700002201850700002101872856007401893 2013 d00aA validation of a ray-tracing tool used to generate bi-directional scattering distribution functions for complex fenestration systems0 avalidation of a raytracing tool used to generate bidirectional s c12/2013 a404-4140 v983 a

Fenestration attachments are anticipated to produce significant reductions in building energy use because they can be deployed quickly at low-cost. New software tools enable users to assess the building energy impacts of optically complex fenestration systems (CFS) such as shades, Venetian blinds, or daylighting systems. However, such tools require users to provide bi-directional scattering distribution function (BSDF) data that describe the solar-optical performance of the CFS. A free, open-source Radiance tool genBSDF enables users to generate BSDF data for arbitrary CFS. Prior to genBSDF, BSDF data for arbitrary fenestration systems could only be produced using either expensive software or with expensive equipment. genBSDF outputs CFS data in the Window 6 XML file format and so can be used with CFS-enabled software tools to model multi-layered window systems composed of glazing and shading layers.

We explain the basis and use of the genBSDF tool and validate the tool by comparing results for four different cases to BSDF data produced via alternate methods. This validation demonstrates that BSDFs created with genBSDF are comparable to BSDFs generated analytically using TracePro and by measurement with a scanning goniophotometer. This tool is expected to support accelerated adoption of fenestration attachments and daylighting technologies.

10aBi-directional scattering distribution function10aComplex fenestration systems10adaylighting10aSolar heat gain1 aMcNeil, Andrew1 aJonsson, Jacob, C.1 aAppelfeld, David1 aWard, Gregory, J.1 aLee, Eleanor, S. uhttps://facades.lbl.gov/publications/validation-ray-tracing-tool-used02907nas a2200157 4500008003900000245014300039210006900182260002200251520231100273653001602584653002702600653003502627653002102662100002002683856004602703 2012 d00aEffective Daylighting: Evaluating Daylighting Performance in the San Francisco Federal Building from the Perspective of Building Occupants0 aEffective Daylighting Evaluating Daylighting Performance in the  aBerkeleyc01/20123 a

Commercial office buildings promoted as “sustainable,” “energy efficient,” “green,” or “high performance” often reference use of daylight as a key strategy for reducing energy consumption and enhancing indoor environmental quality. However, buildings are rarely studied in use to examine if the design intent of a sufficiently daylit and a visually comfortable work environment is achieved from the perspective of building occupants or how occupant use of shading devices may affect electrical lighting energy reduction from photocontrols. This dissertation develops a field-based approach to daylighting performance assessment that pairs repeated measures of occupant subjective response using a novel desktop polling station device with measurements of the physical environment acquired using High Dynamic Range (HDR) imaging and other environmental sensors with the objective of understanding the physical environmental conditions acceptable to occupants. The approach is demonstrated with a 6-month field study involving (N=44) occupants located in perimeter and core open-plan office spaces in the San Francisco Federal Building1 (SFFB). Over 23,100 subjective assessments paired with physical measures were analyzed to develop models of visual discomfort and shade control and to examine the assumptions of existing daylighting performance indicators. The analysis found that existing daylight performance indicators overestimated the levels of daylight illuminance required by occupants to work comfortably without overhead ambient electrical lighting. Time-lapse observation of interior roller shades showed that existing shade control models overestimated the frequency of shade operation and underestimated the level of facade occlusion due to interior shades. Comparison of measured results to the daylighting objectives of the SFFB showed that available daylight enabled electrical lighting energy reduction in the perimeter zones but not in the open-plan core zones. The results extend existing knowledge regarding the amount of daylight illuminance acceptable for occupants to work comfortably without overhead electrical lighting and for the physical variables (and stimulus intensities) associated with visual discomfort and the operation of interior shading devices.

10adaylighting10aperformance assessment10aSan Francisco Federal Building10ashading controls1 aKonis, Kyle, S. uhttps://escholarship.org/uc/item/7q35m7nq02357nas a2200229 4500008003900000245008900039210006900128260001200197300001200209490000700221520162300228653003201851653002001883653001601903653002701919653002301946653002601969100002101995700002402016700001902040856006802059 2012 d00aEnd User Impacts of Automated Electrochromic Windows in a Pilot Retrofit Application0 aEnd User Impacts of Automated Electrochromic Windows in a Pilot  c04/2012 a267-2840 v473 a

Automated electrochromic (EC) windows, advanced thermally-improved window frames, and a dimmable lighting system were installed in a single, west-facing conference room in Washington DC. The EC windows were commercially-available, tungsten-oxide switchable devices, modulated automatically between either fully clear or fully tinted transparent states to control solar gains, daylight, and discomfort glare. Occupants were permitted to manually override the automated EC controls. The system was monitored over a 15-month period under normal occupied conditions. The last six months were used in the analysis. Manual override data were analyzed to assess the EC control system design and user satisfaction with EC operations. Energy and comfort were evaluated using both monitored data and simulations.

Of the 328 meetings that occurred over the six month period, the automatic system was manually overridden on 14 or 4% of the meetings for reasons other than demonstration purposes. When overridden, occupants appeared to have switched the individual zones with deliberation, using a combination of clear and tinted zones and the interior Venetian blinds to produce the desired interior environment. Monitored weekday lighting energy savings were 91% compared to the existing lighting system, which was less efficient, had a higher illuminance setpoint, and no controls. Annual performance was estimated using EnergyPlus, where the existing condition met the ASHRAE 90.1-2007 prescriptive requirements except for a higher window U-value. Annual energy savings were 48% while peak demand savings were 35%.

10abuildings energy efficiency10acontrol systems10adaylighting10aElectrochromic windows10aIntegrated systems10aIntelligent buildings1 aLee, Eleanor, S.1 aClaybaugh, Erin, S.1 aLaFrance, Marc uhttps://facades.lbl.gov/publications/end-user-impacts-automated00704nas a2200181 4500008003900000245014600039210006900185260001200254490001500266653005200281653003200333653001600365653001300381653001500394100001900409700002100428856007300449 2012 d00aA validation of the Radiance three-phase simulation method for modeling annual daylight performance of optically-complex fenestration systems0 avalidation of the Radiance threephase simulation method for mode c05/20120 vApril 201210abidirectional scattering distribution functions10abuildings energy efficiency10adaylighting10aradiance10avalidation1 aMcNeil, Andrew1 aLee, Eleanor, S. uhttps://facades.lbl.gov/publications/validation-radiance-three-phase02267nas a2200229 4500008004100000245011200041210006900153260001200222300001200234490000700246520149000253653003501743653004001778653001601818653002301834653002701857100002201884700001801906700002001924700002101944856007201965 2011 eng d00aPerformance of Integrated Systems of Automated Roller Shade Systems and Daylight Responsive Dimming Systems0 aPerformance of Integrated Systems of Automated Roller Shade Syst c03/2011 a747-7570 v463 a

Daylight responsive dimming systems have been used in few buildings to date because they require improvements to improve reliability. The key underlying factor contributing to poor performance is the variability of the ratio of the photosensor signal to daylight workplane illuminance in accordance with sun position, sky condition, and fenestration condition. Therefore, this paper describes the integrated systems between automated roller shade systems and daylight responsive dimming systems with an improved closed-loop proportional control algorithm, and the relative performance of the integrated systems and single systems. The concept of the improved closed-loop proportional control algorithm for the integrated systems is to predict the varying correlation of photosensor signal to daylight workplane illuminance according to roller shade height and sky conditions for improvement of the system accuracy. In this study, the performance of the integrated systems with two improved closed-loop proportional control algorithms was compared with that of the current (modified) closed-loop proportional control algorithm. In the results, the average maintenance percentage and the average discrepancies of the target illuminance, as well as the average time under 90% of target illuminance for the integrated systems significantly improved in comparison with the current closed-loop proportional control algorithm for daylight responsive dimming systems as a single system.

10aautomated roller shade systems10adaylight responsive dimming systems10adaylighting10aIntegrated systems10aphotoelectric controls1 aPark, Byoung-Chul1 aChoi, An-Seop1 aJeong, Jae-Weon1 aLee, Eleanor, S. uhttps://facades.lbl.gov/publications/performance-integrated-systems04075nas a2200265 4500008003900000245014000039210006900179260002200248520314300270653003503413653002803448653001603476653002003492653002203512653001903534100002103553700002203574700002203596700002403618700002003642700002203662700002803684700002703712856007003739 2007 d00aDaylighting the New York Times Headquarters Building: Final Report: Commissioning Daylighting Systems and Estimation of Demand Response0 aDaylighting the New York Times Headquarters Building Final Repor aBerkeleyc08/20073 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 many innovations, the problem with accelerating market adoption is one of demonstrating real performance and decreasing risk and cost. The New York Times considered use of such daylighting systems for their new 139,426 m2 (1.5 Mft2) headquarters building in downtown Manhattan.

In the initial phase of work, The New York Times employed a unique approach to create a competitive marketplace for daylighting systems and to address their concerns about risk by building a full-scale daylighting mockup and evaluating commercially-available products. This field test formed the strategic cornerstone for accelerating an industry response to the building owners' challenge to a sleepy market. A procurement specification was produced and bids were received that met The Times cost-effective criteria. The Times decided to proceed with using these innovative systems in their new building.

This next phase of work consisted of two distinct tasks: 1) to develop and use commissioning tools and procedures to insure that the automated shade and daylighting control systems operate as intended prior to occupancy; and 2) to estimate the peak demand savings resulting from different levels of demand response (DR) control strategies (from moderate to severe load curtailment) and then determine the financial implications given various DR programs offered by the local utility and New York Independent System Operator in the area.

Commissioning daylighting control systems is mandatory to insure that design intent is met, that the systems are tuned to optimal performance, and to eliminate problems and errors before occupants move in. Commissioning tools were developed and procedures were defined and then used to verify that the daylighting systems operated according to the technical specifications. For both lighting control and shading systems, the Times and the manufacturers were able to resolve most of the bugs and fine-tune the systems prior to occupancy.

The demand response (DR) strategies at the New York Times building involve unique state-of-the-art systems with dimmable ballasts, movable shades on the glass facade, and underfloor air HVAC. The process to develop the demand response strategies, the results of the EnergyPlus model, the activities to implement the DR strategies in the controls design at the New York Times Headquarters building and the evaluation of economics of participating in DR programs are presented and discussed. The DR simulation iv efforts for this building design are novel, with an innovative building owner evaluating DR and future DR program participation strategies during the design and construction phase using advanced simulation tools.

10aautomated daylighting controls10aautomated window shades10adaylighting10ademand response10aenergy-efficiency10avisual comfort1 aLee, Eleanor, S.1 aHughes, Glenn, D.1 aClear, Robert, D.1 aFernandes, Luis, L.1 aKiliccote, Sila1 aPiette, Mary, Ann1 aRubinstein, Francis, M.1 aSelkowitz, Stephen, E. uhttps://facades.lbl.gov/publications/daylighting-new-york-times-002703nas a2200205 4500008004100000245008300041210006900124260001200193300001400205490000700219520204000226653002402266653002302290653001602313653002702329653002202356100002102378700001902399856007902418 2007 eng d00aEnergy and visual comfort performance of electrochromic windows with overhangs0 aEnergy and visual comfort performance of electrochromic windows  c06/2007 a2439-24490 v423 a

DOE-2 building energy simulations were conducted to determine if there were practical architectural and control strategy solutions that would enable electrochromic (EC) windows to significantly improve visual comfort without eroding energy-efficiency benefits. EC windows were combined with overhangs since opaque overhangs provide protection from direct sun which EC windows are unable to do alone. The window wall was divided into an upper and lower aperture so that various combinations of overhang position and control strategies could be considered. The overhang was positioned either at the top of the upper window aperture or between the upper and lower apertures. Overhang depth was varied. EC control strategies were fully bleached at all times, modulated based on incident vertical solar radiation limits, or modulated to meet the design work plane illuminance with daylight. The EC performance was compared to a state-of-the-art spectrally selective low-e window with the same divided window wall, window size, and overhang as the EC configuration. The reference window was also combined with an interior shade which was manually deployed to control glare and direct sun. Both systems had the same daylighting control system to dim the electric lighting. Results were given for south-facing private offices in a typical commercial building.

In hot and cold climates such as Houston and Chicago, EC windows with overhangs can significantly reduce the average annual daylight glare index (DGI) and deliver significant annual energy use savings if the window area is large. Total primary annual energy use was increased by 2-5% for moderate-area windows in either climate but decreased by 10% in Chicago and 5% in Houston for large-area windows. Peak electric demand can be reduced by 7-8% for moderate-area windows and by 14-16% for large-area windows in either climate. Energy and peak demand reductions can be significantly greater if the reference case does not have exterior shading or state-of-the-art glass.

10abuilding simulation10aControl algorithms10adaylighting10aElectrochromic windows10aenergy efficiency1 aLee, Eleanor, S.1 aTavil, Aslihan uhttps://facades.lbl.gov/publications/energy-and-visual-comfort-performance02657nas 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-times01544nas a2200241 4500008004100000245010200041210006900143260001200212300001200224490000700236520078600243653001301029653001201042653002501054653001601079653001301095100002101108700002101129700002201150700002901172700002701201856007401228 1998 eng d00aOffice Worker Response to an Automated Venetian Blind and Electric Lighting System: A Pilot Study0 aOffice Worker Response to an Automated Venetian Blind and Electr c10/1998 a205-2180 v283 a

A prototype integrated, dynamic building envelope and lighting system designed to optimize daylight admission and solar heat gain rejection on a real-time basis in a commercial office building is evaluated. Office worker response to the system and occupant-based modifications to the control system are investigated to determine if the design and operation of the prototype system can be improved. Key findings from the study are: (1) the prototype integrated envelope and lighting system is ready for field testing, (2) most office workers (N=14) were satisfied with the system, and (3) there were few complaints. Additional studies are needed to explain how illuminance distribution, lighting quality, and room design can affect workplane illuminance preferences.

10abehavior10aComfort10acommercial buildings10adaylighting10aenvelope1 aVine, Edward, L.1 aLee, Eleanor, S.1 aClear, Robert, D.1 aDiBartolomeo, Dennis, L.1 aSelkowitz, Stephen, E. uhttps://facades.lbl.gov/publications/office-worker-response-automated