Simulating the Daylight Performance of Complex Fenestration Systems Using Bidirectional Scattering Distribution Functions within Radiance

Ward, Greg; Mistrick, Richard G.; Lee, Eleanor S.; McNeil, Andrew; Jonsson, Jacob C.

doi:10.1080/15502724.2011.10732150

Cited by 106 publications

(63 citation statements)

References 7 publications

(7 reference statements)

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“…The three-phase method (dctimestep) in Radiance (Ward et al 2010) is used to determine indoor daylight illuminance levels, absorbed solar radiation on the glazing and shading layers of the façade, and incident solar radiation on room surfaces. The latter two outputs are used as input to the Modelica window (Nouidui et al 2012) and room thermal models to calculate window heat gains and perimeter zone thermal loads.…”

Section: Dynamic Façade Lookup Tablementioning

confidence: 99%

Integrated control of dynamic facades and distributed energy resources for energy cost minimization in commercial buildings

et al. 2015

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Controllable window, shading, and daylighting technologies provide an interesting opportunity to manage end use demands on distributed energy resources (DER) in ways that both complements the peak output profile of solar photovoltaic (PV) electricity generation and counteracts the peak demands on the utility grid produced by daytime commercial activities. The objective of this study is to explore whether dynamic facade technologies can play an enabling role in supporting a desired level of electricity service at either minimum operating cost or minimum carbon footprint through optimized integrated control with distributed energy resources. A proof-of-concept control system was developed by approximating nonlinearities as piecewise-linear and determining the control state of both the demand and supply side components through global optimization. Annual simulations of a south-facing office zone with switchable electrochromic windows, solar photovoltaic electricity generation, and battery storage indicated that with optimized integrated demand-supply side controls, the utility grid load profile could be lowered to nearly zero demand (5 W/m 2 ) during the daytime when energy costs are highest. A full-scale outdoor field test in Berkeley, California verified this performance, demonstrating that during a week of sunny winter weather, electricity bills could be reduced by 63% compared to heuristic control of electrochromic windows without the photovoltaics and electrical storage. In both the simulated and measured cases, the photovoltaic system was sized to meet the peak perimeter zone load and the electrical storage was sized to be fully discharged by the end of the peak day. Technical and market challenges for achieving reliable optimal control for widespread applications are discussed.

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Section: Dynamic Façade Lookup Tablementioning

confidence: 99%

Integrated control of dynamic facades and distributed energy resources for energy cost minimization in commercial buildings

et al. 2015

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“…This validation focused solely on the Klems angle basis because characterization of systems using the tensor tree format is still under development. Further, validating the accuracy of genBSDF produced Klems BSDFs is an important step in ensuring reliable data is available for simulating whole building energy with CFS and calculating annual daylight metrics for CFS with using the Radiance three-phase method (Ward et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

A validation of a ray-tracing tool used to generate bi-directional scattering distribution functions for complex fenestration systems

et al. 2013

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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 CFSenabled 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.

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“…Although lighting simulation software, such as Radiance [11,12,13] has been able to perform lighting calculations in which the optical properties of materials are determined by BSDF data, the same has not been the case with whole-building simulation software. Programs such as EnergyPlus [14] have used simplified algorithms to determine the transmission of daylight and solar heat gains through fenestration.…”

Section: Computer Simulation Of Optically-complex Fenestrationmentioning

confidence: 99%

“…Several Radiance programs have been developed to enable the modeling of optically complex fenestration systems (CFS) [11,12,13] based on a matrix representation of the propagation of radiation through multilayer windows [7,8]. genBSDF [16] generates bi-directional scattering distribution function (BSDF) data for optically-complex fenestration layers.…”

Section: Radiancementioning

confidence: 99%

Angular selective window systems: Assessment of technical potential for energy savings

Fernandes

Lee

McNeil

et al. 2015

Energy and Buildings

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Static angular selective shading systems block direct sunlight and admit daylight within a specific range of incident solar angles. The objective of this study is to quantify their potential to reduce energy use and peak demand in commercial buildings using state-of-the art whole-building computer simulation software that allows accurate modeling of the behavior of optically-complex fenestration systems such as angular selective systems. Three commercial systems were evaluated: a micro-perforated screen, a tubular shading structure, and an expanded metal mesh. This evaluation was performed through computer simulation for 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). The modeling of the optical complexity of the systems took advantage of the development of state-of-the-art versions of the EnergyPlus, Radiance and Window simulation tools. Results show significant reductions in perimeter zone energy use; the best system reached 28% and 47% savings, respectively without and with daylighting controls (ASHRAE 90.1-2004, south facade, Chicago,WWR=0.45). Angular selectivity and thermal conductance of the angle-selective layer, as well as spectral selectivity of low-emissivity coatings, were identified as factors with significant impact on performance.

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Simulating the Daylight Performance of Complex Fenestration Systems Using Bidirectional Scattering Distribution Functions within Radiance

Cited by 106 publications

References 7 publications

Integrated control of dynamic facades and distributed energy resources for energy cost minimization in commercial buildings

Integrated control of dynamic facades and distributed energy resources for energy cost minimization in commercial buildings

A validation of a ray-tracing tool used to generate bi-directional scattering distribution functions for complex fenestration systems

Angular selective window systems: Assessment of technical potential for energy savings

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