@article {31851, title = {Split-pane electrochromic window control based on an embedded photometric device with real-time daylighting computing}, journal = {Building and Environment}, volume = {161}, year = {2019}, month = {08/2019}, pages = {106229}, abstract = {

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. {\textquoteright}In-situ{\textquoteright} 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.

}, keywords = {daylighting, electrochromic, Embedded Controller, HDR, windows}, issn = {03601323}, doi = {10.1016/j.buildenv.2019.106229}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0360132319304391}, author = {Yujie Wu and Taoning Wang and Eleanor S. Lee and J{\'e}r{\^o}me H. K{\"a}mpf and Jean-Louis Scartezzini} } @article {31495, title = {Efficient modeling of optically-complex, non-coplanar exterior shading: Validation of matrix algebraic methods}, journal = {Energy and Buildings}, volume = {174}, year = {2018}, month = {09/2018}, pages = {464 - 483}, abstract = {

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.

}, keywords = {bidirectional scattering distribution function (BSDF), daylighting, exterior shading, solar heat gains, validation; building energy simulation tools, windows.}, issn = {03787788}, doi = {10.1016/j.enbuild.2018.06.022}, url = {https://www.sciencedirect.com/science/article/pii/S0378778818302457?via\%3Dihub}, author = {Taoning Wang and Gregory Ward and Eleanor S. Lee} } @techreport {29657, title = {Demonstration of Energy Efficient Retrofits for Lighting and Daylighting in New York City Office Buildings}, year = {2017}, month = {04/2017}, abstract = {

The U.S. Department of Energy{\textquoteright}s (DOE) Commercial Buildings Integration (CBI) program{\textquoteright}s mission (and that of the New York State Energy Research \& Development Authority (NYSERDA)) is to accelerate the adoption of cost-effective, underutilized building technologies with large energy savings potential. The key question which CBI asks for each high impact technology is: "What can the DOE do to improve the market adoption of this technology?" Answering this relies on an assessment of the most significant barriers, including:

Innovative, automated shading and LED lighting controls were identified as key technologies that have the potential to significantly reduce perimeter zone energy use and peak demand in existing commercial buildings.\  Technological advances in the field of low-cost embedded controls have enabled high-resolution sensing and more optimal control on a per fixture or shade basis. The Lawrence Berkeley National Laboratory (LBNL) partnered with the Building Energy Exchange (BEEx) and a commercial building owner to evaluate leading-edge technologies on a 40,000 ft2 floor in an occupied, high-rise commercial office building in New York, New York. This {\textquotedblleft}Living Laboratory{\textquotedblright} was monitored for a year prior to and six months following the installation of four sets of lighting and shading technologies and their performance was compared to a parallel reference floor in the same building.

The Living Laboratory demonstrated that there were many competitive products on the market, that the products were able to meet current needs, and that the various advanced features provided significant added value over and above that of conventional products. Monitored data provided detailed insights into how and why each technology performed the way it did, and what the impacts were on energy-efficiency, peak demand, visual and thermal comfort, indoor environmental quality, and occupant acceptance and satisfaction within the resultant environment.

}, author = {Eleanor S. Lee and Luis L. Fernandes and Taoning Wang and Stephen E. Selkowitz and Steven Mesh and Yetsuh Frank and Richard Yancey} } @techreport {60771, title = {High Performance Building Fa{\c c}ade Solutions-Phase II}, year = {2014}, month = {03/2014}, abstract = {

The High Performance Building Fa{\c c}ade Solutions{\textendash}Phase II project was initiated through the California Energy Commission{\textquoteright}s Public Interest Energy Research (PIER) program in July 2010 to support industry{\textquoteright}s development and deployment of both incremental and breakthrough fa{\c c}ade 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 fa{\c c}ade 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 fa{\c c}ade 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{\textquoteright}s long-term goal of achieving zero net energy use in the next decade.

}, keywords = {automated shading, between-pane shading, bidirectional scattering distribution functions, building energy simulation tools, Complex fenestration systems, daylighting, daylighting simulation tools, electrochromics, exterior shading, goniophotometer, light shelves, microprismatic films, model predictive controls, motorized shading, shading, solar-optical properties, switchable windows, thermochromics, virtual prototyping, window heat transfer}, author = {Eleanor S. Lee and Brian E. Coffey and Luis L. Fernandes and Sabine Hoffmann and Andrew McNeil and Anothai Thanachareonkit and Gregory J. Ward} } @article {57094, title = {Acceleration of the matrix multiplication of Radiance three phase daylighting simulations with parallel computing on heterogeneous hardware of personal computer}, journal = {Journal of Building Performance Simulation}, year = {2013}, abstract = {

Building designers are increasingly relying on complex fenestration systems to reduce energy consumed for lighting and HVAC in low energy buildings. Radiance, a lighting simulation program, has been used to conduct daylighting simulations for complex fenestration systems. Depending on the configurations, the simulation can take hours or even days using a personal computer. This paper describes how to accelerate the matrix multiplication portion of a Radiance three-phase daylight simulation by conducting parallel computing on heterogeneous hardware of a personal computer. The algorithm was optimized and the computational part was implemented in parallel using OpenCL. The speed of new approach was evaluated using various daylighting simulation cases on a multicore central processing unit and a graphics processing unit. Based on the measurements and analysis of the time usage for the Radiance daylighting simulation, further speedups can be achieved by using fast I/O devices and storing the data in a binary format.

}, keywords = {daylighting simulation, graphics processing unit, multicore central processing unit, OpenCL, parallel computing}, doi = {10.1080/19401493.2013.795193}, author = {Wangda Zuo and Andrew McNeil and Michael Wetter and Eleanor S. Lee} } @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} } @techreport {3441, title = {A Post-Occupancy Monitored Evaluation of the Dimmable Lighting, Automated Shading, and Underfloor Air Distribution System in The New York Times Building}, year = {2013}, month = {01/2013}, institution = {Lawrence Berkeley National Laboratory}, address = {Berkeley, CA}, abstract = {

With aggressive goals to reduce national energy use and carbon emissions, the US Department of Energy will be looking to exemplary buildings that have already invested in new approaches to achieving the energy performance goals now needed at a national level. The New York Times Building, in New York, New York, incorporates a number of innovative technologies, systems and processes and could become a model for widespread replication in new and existing buildings. Post-occupancy data are invaluable in establishing confidence in innovation. A year-long monitored study was conducted to verify energy performance, assess occupant comfort and satisfaction with the indoor environment, and evaluate impacts on maintenance and operations. Lessons learned were derived from the analysis; these lessons could help identify and shape policy, financial, or supporting strategies to accelerate diffusion in the commercial building market.

}, author = {Eleanor S. Lee and Luis L. Fernandes and Brian E. Coffey and Andrew McNeil and Robert D. Clear and Thomas L. Webster and Fred S. Bauman and Darryl J. Dickerhoff and David Heinzerling and Tyler Hoyt} } @article {57298, title = {A validation of a ray-tracing tool used to generate bi-directional scattering distribution functions for complex fenestration systems}, journal = {Solar Energy}, volume = {98}, year = {2013}, month = {12/2013}, pages = {404-414}, abstract = {

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.

}, keywords = {Bi-directional scattering distribution function, Complex fenestration systems, daylighting, Solar heat gain}, doi = {10.1016/j.solener.2013.09.032}, author = {Andrew McNeil and Jacob C. Jonsson and Appelfeld, David and Gregory J. Ward and Eleanor S. Lee} } @techreport {1211, title = {Conditioning anisotropic BSDF measurements for lighting and daylighting simulation}, year = {2012}, month = {09/2012}, type = {DOE/ LBNL FY12 Technical Report Deliverable}, address = {Berkeley}, abstract = {

This report describes the requirements for utilizing bidirectional scattering distribution function (BSDF) measurements produced by the PAB-Opto goniophotometer and similar devices in simulation tools such as Radiance, and describes progress to date in implementing these methods. An interpolation technique has been identified for resampling the measured data, and an initial implementation has been produced. Work continues on improving this technique and software so it may be employed in a streamlined process for reducing BSDF measurements to a usable form and distributed as variable-resolution XML data. This data may then be employed by lighting simulation software to model complex fenestration systems.

}, author = {Gregory J. Ward} } @techreport {3419, title = {A Practical Framework for Sharing and Rendering Real-World Bidirectional Scattering Distribution Functions}, year = {2012}, month = {10/2012}, abstract = {

The utilization of real-world materials has been hindered by a lack of standards for sharing and interpreting measured data. This paper presents an XML representation and an Open Source C library to support bidirectional scattering distribution functions (BSDFs) in data-driven lighting simulation and rendering applications.The library provides for the efficient representation, query, and Monte Carlo sampling of arbitrary BSDFs in amodel-free framework. Currently, we support two BSDF data representations: one using a fixed subdivision of thehemisphere, and one with adaptive density. The fixed type has advantages for certain matrix operations, while theadaptive type can more accurately represent highly peaked data. We discuss advanced methods for data-driven BSDF rendering for both types, including the proxy of detailed geometry to enhance appearance and accuracy. We also present an advanced interpolation method to reduce measured data into these standard representations. We end with our plan for future extensions and sharing of BSDF data.

}, keywords = {building technology and urban systems department, windows and envelope materials group}, author = {Gregory J. Ward and Murat Kurt and Nicolas Bonneel} } @techreport {3182, title = {Validation of the Window Model of the Modelica Buildings Library}, year = {2012}, month = {07/2012}, abstract = {

This paper describes the validation of the window model of the free open-source Modelica Buildings library. This paper starts by describing the physical modeling assumptions of the window model. The window model can be used to calculate the thermal and angular properties of glazing systems. It can also be used for steady-state simulation of heat transfer mechanism in glazing systems. We present simulation results obtained by comparing the window model with WINDOW 6 the well established simulation tool for steady-state heat transfer in glazing systems. We also present results obtained by comparing the window model with measurements carried out in a test cell at the Lawrence Berkeley National Laboratory.

}, author = {Thierry Stephane Nouidui and Michael Wetter and Wangda Zuo} } @conference {3385, title = {Acceleration of Radiance for Lighting Simulation by using Parallel Computing with OpenCL}, booktitle = {12th International Conference of the International Building Performance Simulation Association (Building Simulation 2011)}, year = {2011}, month = {11/2011}, pages = {p. 110-117}, address = {Sydney, Australia}, abstract = {

This study attempted to accelerate annual daylighting simulations for fenestration systems in Radiance ray-tracing program. The algorithm was optimized to reduce both the redundant data input/output operations and floating-point operations. To further accelerate the simulation speed, calculation for matrices multiplications was implemented in parallel on a graphics processing unit using OpenCL, a cross-platform parallel programming language. Numerical experiments show that combination of above measures can speed up the annual daylighting simulations 101.7 times or 28.6 times when sky vector has 146 or 2306 elements, respectively.

}, author = {Wangda Zuo and Andrew McNeil and Michael Wetter and Eleanor S. Lee} } @article {2974, title = {Achieving high mobility ZnO:Al at very high growth rates by dc filtered cathodic arc deposition}, journal = {Journal of Physics D: Applied Physics}, volume = {44}, year = {2011}, pages = {232003-232007}, chapter = {232003}, abstract = {

Achieving a high growth rate is paramount for making large-area transparent conducting oxide coatings at a low cost. Unfortunately, the quality of thin films grown by most techniques degrades as the growth rate increases. Filtered dc cathodic arc is a lesser known technique which produces a stream of highly ionized plasma, in stark contrast to the neutral atoms produced by standard sputter sources. Ions bring a large amount of potential energy to the growing surface which is in the form of heat, not momentum. By minimizing the distance from cathode to substrate, the high ion flux gives a very high effective growth temperature near the film surface without causing damage from bombardment. The high surface temperature is a direct consequence of the high growth rate and allows for high-quality crystal growth. Using this technique, 500{\textendash}1300\ nm thick and highly transparent ZnO\ :\ Al films were grown on glass at rates exceeding 250\ nm\ min-1 while maintaining resistivity below 5 {\texttimes} 10-4\ Ω\ cm with electron mobility as high as 60\ cm2\ V-1\ s-1.

}, doi = {10.1088/0022-3727/44/23/232003}, author = {Rueben J. Mendelsberg and Sunnie H.N. Lim and Yuankun Zhu and Joe Wallig and Delia J. Milliron and Andr{\'e} Anders} } @techreport {1215, title = {Computing and applying variable-resolution data for bidirectional scattering distribution functions}, year = {2011}, month = {09/2011}, type = {DOE Technical Report}, abstract = {

We introduce the Tensor Tree representation for bidirectional scattering distribution functions (BSDFs), a variable-resolution data structure designed to minimize storage and computation. We offer a method for reducing full-resolution BSDF data into this format, and relate techniques for the efficient generation of uniformly weighted Monte Carlo samples. The Tensor Tree BSDF representation has been tested and incorporated into the 4.1 release of LBNL{\textquoteright}s Radiance lighting simulation and rendering system, with additional methods for modeling the appearance of complex fenestration systems. Finally, an independent software library is described for third-party developers who wish to support BSDF data outside of Radiance, and recommendations are made for future development directions.

}, author = {Gregory J. Ward} } @conference {58301, title = {Co-simulation based building controls implementation with networked sensors and actuators}, booktitle = {Third ACM Workshop on Embedded Sensing Systems for Energy-Efficiency in Buildings}, volume = {Proceedings of BuildSys 2011}, year = {2011}, month = {11/2011}, pages = {55}, publisher = {ACM Press}, organization = {ACM Press}, address = {Seattle, Washington}, abstract = {

The commercial building sector is one of the largest energy consumers in the U.S., and lighting, heating, ventilating and air conditioning contribute to more than half of the energy consumption and carbon emissions in buildings. Controls are the most effective way of increasing energy efficiency in building systems; however, the interdependencies among building subsystems must be taken into account to achieve deep energy savings. A networked sensing and actuation infrastructure shared among building systems is the key to optimal integrated control of the interdependent building elements in low energy and zero net energy buildings.

This paper presents a rapid-prototyping controls implementation platform based on the Building Controls Virtual Test Bed (BCVTB) framework that is capable of linking to building sensor and actuator networks for efficient controller design and testing. The platform creates a separation between the controls and the physical systems so that the controller can easily be implemented, tested and tuned with real performance feedback from a physical implementation. We realized an integrated lighting control algorithm using such a rapid-prototyping platform in a testing facility with networked sensors and actuators. This implementation has demonstrated an up to 57\% savings in lighting electricity and 28\% reduction in cooling demand.

}, isbn = {9781450307499}, doi = {10.1145/2434020.2434040}, author = {Yao-Jung Wen and Dennis L. DiBartolomeo and Francis M. Rubinstein} } @book {58278, title = {GenOpt Generic Optimization Program, User Manual, Version 3.1.0}, year = {2011}, month = {12/2011}, publisher = {Simulation Research Group, Lawrence Berkeley National Laboratory}, organization = {Simulation Research Group, Lawrence Berkeley National Laboratory}, address = {Berkeley}, abstract = {

GenOpt is an optimization program for the minimization of a cost function that is evaluated by an external simulation program. It has been developed for optimization problems where the cost function is computationally expensive and its derivatives are not available or may not even exist. GenOpt can be coupled to any simulation programthat reads its input from text files and writes its output to text files. The independent variables can be continuous variables (possibly with lower and upper bounds), discrete variables, or both, continuous and discrete variables. Constraints on dependent variables can be implemented using penalty or barrier functions. GenOpt uses parallel computing to evaluate the simulations. GenOpt has a library with local and global multi-dimensional and one-dimensional optimization algorithms, and algorithms for doing parametric runs. An algorithm interface allows adding new minimization algorithms without knowing the details of the program structure. GenOpt is written in Java so that it is platform independent. The platform independence and the general interface make GenOpt applicable to a wide range of optimization problems. GenOpt has not been designed for linear programming problems, quadratic programming problems, and problems where the gradient of the cost function is available. For such problems, as well as for other problems, special tailored software exists that is more efficient.

}, author = {Michael Wetter} } @techreport {1216, title = {Rapid Prototyping Control Implementation using the Building Controls Virtual Test Bed}, year = {2011}, month = {09/2011}, type = {Philips Technical Report}, abstract = {

This report documents the development of a rapid-prototyping control framework based on the Building Controls Virtual Test Bed co-simulation software. The objective of the developed framework is to establish the separation between the control algorithm and the physical systems such that the control algorithm can be rapidly revised and implemented without having to physically swap the controllers. The corresponding protocols and interfaces are designed for maximal flexibility, easy generalization and straightforward implementation. An instance of such control framework has been realized in the Advanced Windows Testing Facility at the Lawrence Berkeley National Laboratory and is used as a case study throughout this report.

}, author = {Yao-Jung Wen} } @article {1799, title = {Simulating the Daylight Performance of Complex Fenestration Systems Using Bidirectional Scattering Distribution Functions within Radiance}, journal = {Leukos, The Journal of the Illuminating Engineering Society}, volume = {7}, year = {2011}, month = {04/2011}, chapter = {241}, abstract = {

We describe two methods which rely on bidirectional scattering distribution functions (BSDFs) to model the daylighting performance of complex fenestration systems (CFS), enabling greater flexibility and accuracy in evaluating arbitrary assemblies of glazing, shading, and other optically-complex coplanar window systems. Two tools within Radiance enable a) efficient annual performance evaluations of CFS, and b) accurate renderings of CFS despite the loss of spatial resolution associated with low-resolution BSDF datasets for inhomogeneous systems. Validation, accuracy, and limitations of the methods are discussed.

}, keywords = {bidirectional scattering distribution function (BSDF), Complex fenestration systems, daylighting systems, energy, Radiance software, Shading Systems, windows}, issn = {1550-2724}, doi = {10.1080/15502724.2011.10732150}, author = {Gregory J. Ward and Richard G. Mistrick and Eleanor S. Lee and Andrew McNeil and Jacob C. Jonsson} } @conference {61, title = {A Modular Building Controls Virtual Test Bed for the Integration of Heterogeneous Systems}, booktitle = {SimBuild 2008, July 30-August 1}, year = {2008}, month = {08/2008}, address = {Berkeley, CA}, abstract = {

This paper describes the Building Controls Virtual Test Bed (BCVTB) that is currently under development at Lawrence Berkeley National Laboratory. An earlier prototype linked EnergyPlus with controls hardware through embedded SPARK models and demonstrated its value in more cost-effective envelope design and improved controls sequences for the San Francisco Federal Building. The BCVTB presented here is a more modular design based on a middleware that we built using Ptolemy II, a modular software environment for design and analysis of heterogeneous systems. Ptolemy II provides a graphical model building environment, synchronizes the exchanged data and visualizes the system evolution during run-time. Our additions to Ptolemy II allow users to couple to Ptolemy II a prototype version of EnergyPlus, MATLAB/Simulink or other simulation programs for data exchange during run-time. In future work we will also implement a BACnet interface that allows coupling BACnet compliant building automation systems to Ptolemy II. We will present the architecture of the BCVTB and explain how users can add their own simulation programs to the BCVTB. We will then present an example application in which the building envelope and the HVAC system was simulated in EnergyPlus, the supervisory control logic was simulated in MATLAB/Simulink and Ptolemy II was used to exchange data during run-time and to provide real-time visualization as the simulation progresses.

}, author = {Michael Wetter and Philip Haves} } @techreport {58305, title = {Commissioning and verification procedures for the automated roller shade system at The New York Times Headquarters}, year = {2007}, month = {05/2007}, address = {Berkeley}, abstract = {

This document describes the procedures for verification testing of a newly installed automated roller shade system. The automated roller shade system has been designed to control direct sun and window glare while admitting daylight and permitting view out. Procedures in this document focus on verifying that the glare control aspect of this commercially-available system works prior to building occupancy. A high dynamic range luminance measurement tool, developed for this project, is used to verify that the average window luminance is within acceptable limits. Additional spreadsheet and visualization tools are described. The commissioning agent (CxA) and The New York Times will use these procedures during the commissioning phase of the building to verify that the automated control system is operating as intended.

}, author = {Eleanor S. Lee and Robert D. Clear and Gregory J. Ward and Luis L. Fernandes} } @techreport {58306, title = {Quick Start Guide: Commissioning and verification procedures for the automated roller shade system at The New York Times Headquarters}, year = {2007}, month = {05/2007}, address = {Berkeley}, abstract = {

This quick start guide summarizes the steps required to verify the performance of a newly installed automated roller shade system. The automated roller shade system at The New York Times Headquarters has been designed to control direct sun and window glare while admitting daylight and permitting view out. Procedures in this guide focus on verifying that the glare control aspect of this commerciallyavailable system works prior to building occupancy. A high dynamic range luminance measurement tool, developed for this project, is used to verify that the average window luminance is within acceptable limits. The commissioning agent (CxA) and The New York Times will use these procedures during the commissioning phase of the building to verify that the automated control system is operating as intended.

}, author = {Eleanor S. Lee and Robert D. Clear and Gregory J. Ward and Luis L. Fernandes} } @techreport {1077, title = {Advancement of Electrochromic Windows}, year = {2006}, month = {04/2006}, abstract = {

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{\textquoteright}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.

}, keywords = {commercial buildings, daylight, daylighting controls, Electrochromic windows, energy efficiency, human factors, peak demand, switchable windows, visual comfort}, author = {Eleanor S. Lee and Stephen E. Selkowitz and Robert D. Clear and Dennis L. DiBartolomeo and Joseph H. Klems and Luis L. Fernandes and Gregory J. Ward and Vorapat Inkarojrit and Mehry Yazdanian} } @techreport {1264, title = {A Design Guide for Early-Market Electrochromic Windows}, year = {2006}, abstract = {

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.

}, author = {Eleanor S. Lee and Stephen E. Selkowitz and Robert D. Clear and Dennis L. DiBartolomeo and Joseph H. Klems and Luis L. Fernandes and Gregory J. Ward and Vorapat Inkarojrit and Mehry Yazdanian} } @conference {165, title = {Dynamic Controls for Energy Efficiency and Demand Response: Framework Concepts and a New Construction Case Study in New York}, booktitle = {2006 ACEEE Summer Study on Energy Efficiency in Buildings}, year = {2006}, month = {06/2006}, address = {Pacific Grove, CA}, abstract = {

Many of today{\textquoteright}s advanced building control systems are designed to improve granularity of control for energy efficiency. Examples include direct digital controls for building heating, ventilation, and cooling systems (HVAC), and dimmable ballasts for continuous dimming for daylighting applications. This paper discusses recent research on the use of new and existing controls in commercial buildings for integrated energy efficiency and demand response (DR). The paper discusses the use of DR controls strategies in commercial buildings and provides specific details on DR control strategy design concepts for a new building in New York. We present preliminary results from EnergyPlus simulations of the DR strategies at the New York Times Headquarters building currently under construction. The DR strategies at the Times building involve unique state of the art systems with dimmable ballasts, movable shades on the glass facade, and underfloor air HVAC. The simulation efforts at this building are novel, with an innovative building owner considering DR and future DR program participation strategies during the design phase. This paper also discusses commissioning plans for the DR strategies. The trends in integration of various systems through the EMCS, master versus supervisory controls and dynamic operational modes concepts are presented and future research directions are outlined.

}, author = {Sila Kiliccote and Mary Ann Piette and David S. Watson and Glenn D. Hughes} } @techreport {58284, title = {Daylighting the New York Times Headquarters Building: Final Report}, year = {2005}, month = {06/2005}, abstract = {

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{\textquoteright} 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.

}, keywords = {automated daylighting controls, automated window shades, daylighting, energy-efficiency, visual comfort}, author = {Eleanor S. Lee and Stephen E. Selkowitz and Glenn D. Hughes and Robert D. Clear and Gregory J. Ward and John Mardaljevic and Judy Lai and Mehlika Inanici and Vorapat Inkarojrit} } @article {11601, title = {Calculation of Thermodynamic, Electronic, and Optical Properties of Monoclinic Mg2NiH4}, journal = {Journal of Applied Physics}, volume = {91}, number = {8}, year = {2002}, month = {04/2002}, pages = {4879-4885}, chapter = {4879}, abstract = {

Ab initio total-energy density functional theory is used to investigate the low temperature (LT) monoclinic form of Mg2NiH4. The calculated minimum energy geometry of LT\ Mg2NiH4 is close to that determined from neutron diffraction data, and the NiH4 complex is close to a regular tetrahedron. The enthalpies of the phase change to high temperature (HT) pseudo-cubic\ Mg2NiH4 and of hydrogen absorption by Mg2Ni are calculated and compared with experimental values. LT\ Mg2NiH4 is found to be a semiconductor with an indirect band gap of 1.4 eV. The optical dielectric function of LT Mg2NiH4 differs somewhat from that of the HT phase. A calculated thin film transmittance spectrum is consistent with an experimental spectrum.

}, doi = {10.1063/1.1454206}, author = {Whittier R. Myers and Lin-Wang Wang and Thomas J. Richardson and Michael D. Rubin} } @article {11792, title = {Electrochromic lithium nickel oxide by pulsed laser deposition and sputtering}, journal = {Solar Energy Materials and Solar Cells}, volume = {54}, number = {4-Jan}, year = {1998}, month = {07/1998}, pages = {59-66}, chapter = {59}, abstract = {

Thin films of lithium nickel oxide were deposited by sputtering and pulsed laser deposition (PLD) from targets of pressed LiNiO2 powder. The composition and structure of these films were analyzed using a variety of techniques, such as nuclear-reaction analysis, Rutherford backscattering spectrometry (RBS), X-ray diffraction, infrared spectroscopy, and atomic-force microscopy. Crystalline structure, surface morphology and chemical composition of LixNi1-xO thin films depend strongly on deposition oxygen pressure, temperature as well as substrate{\textendash}target distance. The films produced at temperatures lower than 600{\textdegree}C spontaneously absorb CO2 and H2O at their surface once they are exposed to the air. The films deposited at 600{\textdegree}C proved to be stable in air over a long period. Even at room temperature the PLD films are denser and more stable than sputtered films. RBS determined the composition of the best films to be Li0.5Ni0.5O deposited by PLD at 60\ mTorr O2 pressure. Electrochemical tests show that the films exhibit excellent reversibility in the range 1.0{\textendash}3.4\ V versus lithium. Electrochemical formatting which is used to develop electrochromism in other films is not needed for the stoichiometric films. The optical transmission range is almost 70\% at 550\ nm for 150\ nm-thick films. Devices made from these films were analyzed using novel reference electrodes and by disassembling after cycling.

}, keywords = {Lithium nickel oxide, pulsed laser deposition, sputtering}, doi = {10.1016/S0927-0248(97)00223-7}, author = {Michael D. Rubin and Shi-Jie Wen and Thomas J. Richardson and John B. Kerr and Klaus von Rottkay and Jonathan L. Slack} } @techreport {1951, title = {Validation studies of the DOE-2 Building Energy Simulation Program. Final Report}, year = {1998}, abstract = {

This report documents many of the validation studies (Table 1) of the DOE-2 building energy analysis simulation program that have taken place since 1981. Results for several versions of the program are presented with the most recent study conducted in 1996 on version DOE-2.1E and the most distant study conducted in 1981 on version DOE-1.3. This work is part of an effort related to continued development of DOE-2, particularly in its use as a simulation engine for new specialized versions of the program such as the recently released RESFEN 3.1. RESFEN 3.1 is a program specifically dealing with analyzing the energy performance of windows in residential buildings. The intent in providing the results of these validation studies is to give potential users of the program a high degree of confidence in the calculated results.

}, author = {Robert Sullivan and Frederick C. Winkelmann} } @article {12196, title = {Pressure Controlled GaN MBE Growth Using a Hollow Anode Nitrogen Ion Source}, journal = {Materials Research Society Proceedings}, volume = {449}, year = {1997}, note = {

1996 MRS Fall Meeting

}, abstract = {

GaN films were grown on sapphire substrates at temperatures below 1000 K utilizing a Hollow Anode nitrogen ion source. A Ga flux limited growth rate of ~0.5 μm/h is demonstrated. Active utilization of strain and the assistance of a nitrogen partial pressure during buffer layer growth are found to be crucial issues that can improve the film quality. The best films exhibit a full width at half maximum of the x-ray rocking curves of 80 arcsec and 1.85 meV for the excitonic photoluminescence measured at 4 K. A Volmer-Weber three dimensional growth mode and the spontaneous formation of cubic GaN inclusions in the hexagonal matrix are observed in the investigated growth temperature range. It is argued that this growth mode contributes to a limitation of the carrier mobility in these films that did not exceed 120 cm2/Vs through a minimum canier concentration of ~1015 cm-3 was achieved.

}, doi = {10.1557/PROC-449-221}, author = {Michael S.H. Leung and Ralf Klockenbrink and Christian F. Kisielowski and Hiroaki Fujii and Joachim Kr{\"u}ger and Sudhir G. Subramanya and Andr{\'e} Anders and Zuzanna Liliental-Weber and Michael D. Rubin and Eicke R. Weber}, editor = {Joachim Kr{\"u}ger} } @conference {11545, title = {Analysis of Durability in Lithium Nickel Oxide Electrochromic Materials and Devices}, booktitle = {2nd International Meeting on Electrochromism}, year = {1996}, month = {10/1996}, address = {San Diego, CA}, abstract = {

Thin films of lithium nickel oxide were deposited by sputtering and laser ablation from targets of pressed nickel oxide and lithium oxide powders. These films were assembled into electrochromic test devices with tungsten oxide as the opposite electrode and a polymer electrolyte. Analysis of the failure modes was carried out at several levels: The composition and structure of the films were examined before and after cycling using a variety of techniques, such as infrared spectroscopy, nuclear-reaction analysis, Rutherford backscattering spectrometry, x-ray diffraction and atomic force microscopy. Absorption of water vapor was found to be a major factor determining the cyclic stability of the films. A new technique is described for incorporating reference electrodes made from an electronically isolated corner into devices. This structure enabled identification of potential problems associated with a particular interface. Finally, some of the devices were disassembled and the components examined. For example, a small quantity of the polymer was extracted and studied by gas chromatography and mass spectroscopy. Small organic fragments were discovered which correspond to expected weak points in the polymer structures.

}, author = {Shi-Jie Wen and John B. Kerr and Michael D. Rubin and Jonathan L. Slack and Klaus von Rottkay} } @techreport {1254, title = {Design and Evaluation of Daylighting Applications of Holographic Glazings}, year = {1996}, abstract = {

When combined with appropriate electric lighting dimming controls, the use of daylight for ambient and task illumination can significantly reduce energy requirements in commercial buildings. While skylights can effectively illuminate any part of one-story buildings, conventional side windows can illuminate only a 15 ft - 20 ft (4.6 m - 6.1 m) depth of the building perimeter. Even so, the overall efficacy of daylight is limited, because side windows produce uneven distributions of daylight. Achieving adequate illumination at distances further away from the window results in excessive illumination near the window, which increases cooling loads from the associated solar heat gain. As a result, the use of larger apertures and/or higher transmittance glazings, to introduce daylight deeper than 15 ft - 20 ft (4.6 m - 6.1 m), may prove ineffective with respect to saving energy, because cooling load penalties may exceed the electric lighting savings.

The need for more uniform distribution of daylight admitted through side windows has stimulated significant research and development efforts in new fenestration designs and glazing technologies. Many of these approaches, including holographic glazings, rely on the common strategy of redirecting sunlight and reflecting it off the ceiling towards the back of the room. Prior studies on the daylight and energy performance of holographic glazings have been disappointing, however inconclusive because of poor hologram quality, low diffraction efficiency and inadequate hologram design and building application considerations [Papamichael et al 1994].

}, author = {Konstantinos M. Papamichael and Charles K. Ehrlich and Gregory J. Ward} } @conference {11793, title = {Electrochromic Lithium Nickel Oxide Thin Film by Pulsed Laser Deposition}, booktitle = {Electrochemical Society Meeting}, volume = {96-24}, year = {1996}, month = {10/1996}, pages = {54-63}, address = {San Antonio, TX}, abstract = {

Thin films of lithium nickel oxide were deposited by pulsed laser deposition (PLD) from targets of pressed LiNiO2 powder with layered structure. The composition, structure and surface air sensitivity of these films were analyzed using a variety of techniques, such as nuclear reaction analysis, Rutherford backscattering spectrometry (RBS), x-ray diffraction, infrared spectroscopy, and atomic force microscopy. Optical properties were measured using a combination of variable angle spectroscopic ellipsometry and spectroradiometry. Crystalline structure, surface morphology and chemical composition of LixNi1-xO thin films depend strongly on deposition oxygen pressure, temperature as well as substrate target distance. The films produced at temperatures lower than 600 {\textdegree}C spontaneously absorb CO2 and H2O at their surface once they are exposed to the air. The films deposited at 600 {\textdegree}C proved to be stable in air over a long period. Even when deposited at room temperature the PLD films are denser and more stable than sputtered films. RBS determined that the best electrochromic films had the stoichiometric composition Li0.5Ni0.5O when deposited at 60 mTorr O2 pressure. Electrochemical tests show that the films exhibit excellent reversibility in the range 1.0 V to 3.4 V versus lithium and long cyclic life stability in a liquid electrolyte half cell. Electrochemical formatting which is used to develop electrochromism in other films and nickel oxide films is not needed for these stoichiometric films. The optical transmission range is almost 70\% at 550 nm for 120 nm thick films.

}, author = {Shi-Jie Wen and Klaus von Rottkay and Michael D. Rubin} } @proceedings {11942, title = {Impact of Growth Temperature, Pressure and Strain on the Morphology of GaN Films}, journal = {Materials Research Society Symposium N {\textendash} III-V Nitrides}, volume = {449}, year = {1996}, pages = {227}, abstract = {

GaN films grown on sapphire at different temperatures are investigated. A Volmer-Weber growth mode is observed at temperatures below 1000K that leads to thin films composed of oriented grains with finite size. Their size is temperature dependent and can actively be influenced by strain. Largest grains are observed in compressed films. It is argued that diffusing Ga ad-atoms dominate the observed effects with an activation energy of 2.3 {\textpm} 0.5 eV. Comparably large grain sizes are observed in films grown on off-axes sapphire substrates and on bulk GaN. This assures that the observed size limitation is a consequence of the 3D growth mode and not dependent on the choice of the substrate. In addition, the grain size and the surface roughness of the films depend on the nitrogen partial pressure in the molecular beam epitaxy (MBE) chamber,most likely due to collisions between the reactive species and the background gas molecules. This effect is utilized to grow improved nucleation layers on sapphire.

}, doi = {10.1557/PROC-449-227}, author = {Hiroaki Fujii and Christian F. Kisielowski and Joachim Kr{\"u}ger and Michael S.H. Leung and Ralf Klockenbrink and Michael D. Rubin and Eicke R. Weber}, editor = {Joachim Kr{\"u}ger} } @article {12146, title = {Optical Indices of Electrochromic Tungsten Oxide}, journal = {Thin Solid Films}, volume = {306}, number = {1}, year = {1996}, month = {08/1997}, pages = {10-16}, chapter = {10}, abstract = {

Tungsten trioxide (WO3) is the most widely used material for the active layer of electrochromic devices. Knowledge of the complex refractive index over the range of coloration states is required for device design. Optical constants of WO3 over the whole solar spectrum were determined as a function of injected charge. Films of WO3 were prepared by electron-beam evaporation, then colored in several steps by reduction with lithium (Li) up to 68 mC cm-2 {\textmu}m-1 injected charge. Measurements included variable-angle spectroscopic ellipsometry and spectroscopic transmittance and reflectance at normal incidence. Analysis was complicated by the fact that a transparent-conducting layer of indium tin oxide (ITO) was required to perform lithiation. Optical indices of the glass substrate and ITO transparent conductor were determined separately and then fixed in the model. The indices of WO3 could then be extracted from measurements on the complete structure. A parametric dispersion model corresponding to Gaussian broadening of the oscillators was used to represent the dielectric response of WO3.

}, keywords = {Colored state, Complex refractive index, electrochromic, tungsten oxide}, doi = {10.1016/S0040-6090(97)00254-X}, author = {Klaus von Rottkay and Michael D. Rubin and Shi-Jie Wen} } @article {12147, title = {Optical Indices of Lithiated Electrochromic Oxides}, journal = {Solar Energy Materials and Solar Cells}, volume = {54}, number = {4-Jan}, year = {1996}, month = {07/1998}, pages = {49-57}, chapter = {49}, abstract = {

Optical indices have been determined for thin films of several electrochromic oxide materials. One of the most important materials in electrochromic devices, WO3, was thoroughly characterized for a range of electrochromic states by sequential injection of Li ions. Another promising material, Li0.5Ni0.5O, was also studied in detail. Less detailed results are presented for three other common lithium-intercalating electrochromic electrode materials: V2O5, LiCoO2, and CeO2-TiO2. The films were grown by sputtering, pulsed laser deposition (PLD) and sol-gel techniques. Measurements were made using a combination of variable-angle spectroscopic ellipsometry and spectroradiometry. The optical constants were then extracted using physical and spectral models appropriate to each material. Optical indices of the underlying transparent conductors, determined in separate studies, were fixed in the models of this work. The optical models frequently agree well with independent physical measurements of film structure, particularly surface roughness by atomic force microscopy. Inhomogeneity due to surface roughness, gradient composition, and phase separation are common in both the transparent conductors and electrochromics, resulting sometimes in particularly complex models for these materials. Complete sets of data are presented over the entire solar spectrum for a range of colored states. This data is suitable for prediction of additional optical properties such as oblique transmittance and design of complete electrochromic devices.

}, doi = {10.1016/S0927-0248(97)00222-5}, author = {Michael D. Rubin and Klaus von Rottkay and Shi-Jie Wen and Nilg{\"u}n {\"O}zer and Jonathan L. Slack} } @conference {12157, title = {Origin of Strain in GaN Thin Films}, booktitle = {23rd International Conference on the Physics of Semiconductors}, volume = {4}, year = {1996}, pages = {513}, address = {Singapore}, abstract = {

Photoluminescence measurements are used to determine the strain in GaN thin films grown by Molecular Beam Epitaxy. The strain which originates from growth on lattice mismatched substrates and from differences in thermal expansion coefficients is found to be greatly relaxed. Residual strains are shown to depend on the thickness of GaN buffer layers and the III/V flux ration during main layer growth. The results strongly suggest that the residual biaxial strain caused by the post-growth cooling can be modified by the incorporation of point defects during the main layer growth which introduce an additional hydrostatic strain field. The effect allows for strain engineering of GaN crystals.

}, author = {Christian F. Kisielowski and Joachim Kr{\"u}ger and Michael S.H. Leung and Ralf Klockenbrink and Hiroaki Fujii and Tadeusz Suski and Sudhir G. Subramanya and Joel W. Ager III and Michael D. Rubin and Eicke R. Weber}, editor = {Joachim Kr{\"u}ger} } @conference {1819, title = {Solar Heat Gain Coefficient of Complex Fenestrations with a Venetian Blind for Differing Slat Tilt Angles}, booktitle = {ASHRAE Symposium}, volume = {103, Part 1}, year = {1996}, month = {01/1997}, address = {Philadelphia, PA}, abstract = {

Measured bidirectional transmittances and reflectances of a buff-colored venetian blind together with a layer calculation scheme developed in previous publications are utilized to produce directional-hemispherical properties for the venetian blind layer and solar heat gain coefficients for the blind in combination with clear double glazing. Results are presented for three blind slat tilt angles and for the blind mounted either interior to the double glazing or between the glass panes. Implications of the results for solar heat gain calculations are discussed in the context of sun positions for St. Louis, MO.

}, author = {Joseph H. Klems and Jeffrey L. Warner} } @article {1849, title = {Strain Related Phenomena in GaN Thin Films}, journal = {Physical Review B}, volume = {54}, number = {24}, year = {1996}, month = {12/1996}, pages = {17745-17753}, chapter = {17745}, abstract = {

Photoluminescence (PL), Raman spectroscopy, and x-ray diffraction are employed to demonstrate the co-existence of a biaxial and a hydrostatic strain that can be present in GaN thin films. The biaxial strain originates from growth on lattice-mismatched substrates and from post-growth cooling. An additional hydrostatic strain is shown to be introduced by the presence of point defects. A consistent description of the experimental results is derived within the limits of the linear and isotropic elastic theory using a Poisson ratio nu =0.23+/-0.06 and a bulk modulus B=200+/-20 GPa. These isotropic elastic constants help to judge the validity of published anisotropic elastic constants that vary greatly. Calibration constants for strain-induced shifts of the near-band-edge PL lines with respect to the E2 Raman mode are given for strain-free, biaxially strained, and hydrostatically contracted or expanded thin films. They allow us to extract differences between hydrostatic and biaxial stress components if present. In particular, we determine that a biaxial stress of one GPa would shift the near-band-edge PL lines by 27+/-2 meV and the E2 Raman mode by 4.2+/-0.3 cm-1 by use of the listed isotropic elastic constants. It is expected from the analyses that stoichiometric variations in the GaN thin films together with the design of specific buffer layers can be utilized to strain engineer the material to an extent that greatly exceeds the possibilities known from other semiconductor systems because of the largely different covalent radii of the Ga and the N atom.

}, doi = {10.1103/PhysRevB.54.17745}, author = {Christian F. Kisielowski and Joachim Kr{\"u}ger and Sergei Ruvimov and Tadeusz Suski and Joel W. Ager III and Erin C. Jones and Zuzanna Liliental-Weber and Michael D. Rubin and Eicke R. Weber and Michael D. Bremser and Robert F. Davis}, editor = {Joachim Kr{\"u}ger} } @conference {11634, title = {A Comparison Between Calculated and Measured SHGC For Complex Fenestration Systems}, booktitle = {ASHRAE Transactions}, volume = {102, Part 1}, year = {1995}, month = {02/1996}, address = {Atlanta, GA}, abstract = {

Calorimetric measurements of the dynamic net heat flow through a complex fenestration system consisting of a buff venetian blind inside clear double glazing are used to derive the direction-dependent beam SHGC of the fenestration. These measurements are compared with calculations according to a proposed general method for deriving complex fenestration system SHGCs from bidirectional layer optical properties and generic calorimetric properties. Previously published optical measurements of the same venetian blind and generic inward-flowing fraction measurements are used in the calculation. The authors find satisfactory agreement between the SHGC measurements and the calculation.

Significant dependence on incident angle was found in the measured SHGCs. Profile angle was not found to be a useful variable in characterizing the system performance. The predicted SHGC was found to be inherently dependent on two angles, although only the incident angle variations were observable under the test conditions.

}, author = {Joseph H. Klems and Jeffrey L. Warner and Guy O. Kelley} } @conference {11886, title = {Formation of Metal Oxides by Cathodic Arc Deposition}, booktitle = {International Conference on Metallurgical Coatings and Thin Films, April 24-28, 1995}, year = {1995}, month = {04/1995}, address = {San Diego, CA}, abstract = {

Metal oxide thin films are of interest for a number of applications. Cathodic arc deposition, which is an established and industrially applied technique for the formation of nitrides (e.g. TIN), can also be used for metal oxide thin film formation. A cathodic arc plasma source with the desired cathode material is operated in an oxygen atmosphere of appropriate pressure, and metal oxides of various stoichiometric composition can be formed on different substrates. We report here on a series of experiments on metal oxide formation by cathodic arc deposition for different applications. Black copper oxide has been deposited on accelerator components to increase the radiative heat transfer between the parts. Various metal oxides such as tungsten oxide, niobium oxide, nickel oxide and vanadium oxide have been deposited on ITO glass to form electrochromic films for window applications. Tantalum oxide films are of interest for replacing polymer electrolytes. Optical waveguide structures can be formed by refractive index variation using oxide multilayers. We have synthesized multilayers of Al2O3/Y2O3/Al2O3/Si as possible basic structures for passive optoelectronic integrated circuits, and Al2-xErxO3 thin films with a variable Er concentration which is a potential component layer for the production of active optoelectronic integrated devices such as amplifiers or lasers at a wavelength of 1.53 pm. Aluminum and chromium oxide films have been deposited on a number of substrates to impart improved corrosion resistance at high temperature. Titanium sub-oxides which are electrically conductive and corrosion resistant and stable in a number of aggressive environments have been deposited on various substrates. These sub-oxides are of great interest for use in electrochemical cells. Common features of all these depositions are the high deposition rate typical for cathodic arc deposition, the good adhesion of the films due to the high metal ion energy, and the advantage of an environmentally clean method in comparison to wet-chemical oxide formation techniques.

}, keywords = {Cathodic arc deposition, Oxide formation}, url = {http://dx.doi.org/10.1016/0257-8972(95)02508-1}, author = {Simone Anders and Andr{\'e} Anders and Michael D. Rubin and Zhien Wang and Sebastien Raoux and Fanping Kong and Ian G. Brown} } @article {11964, title = {The Influence of Nitrogen Ion Energy on the Quality of GaN Films Grown with Molecular Beam Epitaxy}, journal = {Journal of Electronic Materials}, volume = {24}, number = {4}, year = {1995}, month = {04/1995}, pages = {249-255}, chapter = {249}, abstract = {

Since the growth of GaN using molecular beam epitaxy (MBE) occurs under metastable growth conditions, activated nitrogen is required to drive the forward synthesis reaction. In the process of exciting the nitrogen using a plasma or ion-beam source, species with large kinetic energies are generated. Impingement on the growth surface by these species can result in subsurface damage to the growing film, as well as an enhancement of the reverse decomposition reaction rate. In this study, we investigate the effect of the kinetic energy of the impinging nitrogen ions during growth on the resulting optical and structural properties of GaN films. Strong band-edge photoluminescence and cathodoluminescence are found when a kinetic energy of ~10 eV are used, while luminescence is not detectable when the kinetic energies exceeds 18 eV. Also, we find that the use of conductive SiC substrates results in more homogeneous luminescence than the use of insulating sapphire substrates. This is attributed to sample surface charging in the case of sapphire substrates and subsequent variation in the incident ion flux and kinetic energy across the growth surface.This study clearly shows that the quality of GaN films grown by MBE are presently limited by damage from the impingement of high energy species on the growth surface.

}, keywords = {Activated nitrogen, GaN, molecular beam epitaxy (MBE), nitrogen ion energy}, issn = {0361-5235}, doi = {10.1007/BF02659683}, author = {T.C. Fu and Nathan Newman and Erin C. Jones and James S. Chan and Xiaohong Liu and Michael D. Rubin and Nathan W. Cheung and Eicke R. Weber} } @article {12058, title = {Measurement of Bidirectional Optical Properties of Complex Shading Devices}, journal = {ASHRAE Transactions}, volume = {101, Part 1}, year = {1995}, abstract = {

A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure the bidirectional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorptances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient.

This paper describes the method of measuring the spatially averaged bidirectional optical properties using an automated, large-sample gonio-radiometer/photometer, termed a Scanning Radiometer. Property measurements are presented for one of the most optically complex systems in common use, a venetian blind. These measurements will form the basis for optical system calculations used to test the method of determining performance.

}, author = {Joseph H. Klems and Jeffrey L. Warner} } @article {1900, title = {Thermal Annealing Characteristics of Si and Mg-implanted GaN Thin Films}, journal = {Applied Physics Letters}, volume = {68}, number = {19}, year = {1995}, month = {03/1996}, pages = {2702-2704}, chapter = {2702}, abstract = {

In this letter, we report the results of ion implantation of GaN using 28Si and 23Mg species. Structural and electrical characterizations of the GaN thin films after thermal annealing show that native defects in the GaN films dominate over implant doping effects. The formation energies of the annealing induced defects are estimated to range from 1.4 to 3.6 eV. A 30 keV10^14 cm-2 Mg implant results in the decrease of the free-carrier concentration by three orders of magnitude compared to unimplanted GaN up to an annealing temperature of 690 {\textdegree}C. Furthermore, we have observed the correlation between these annealing-induced defects to both improved optical and electrical properties.

}, keywords = {annealing, crystal doping, defect states, electrical properties, gallium nitrides, ion implantation, magnesium additions, microstructure, silicon additions}, issn = {0003-6951}, doi = {10.1063/1.116314}, author = {James S. Chan and Nathan W. Cheung and Lawrence F. Schloss and Erin C. Jones and William S. Wong and Nathan Newman and Xiaohong Liu and Eicke R. Weber and A. Gassman and Michael D. Rubin} } @conference {11890, title = {Fundamental Materials-Issues Involved in the Growth of GaN by Molecular Beam Epitaxy}, year = {1994}, abstract = {

Gallium nitride is one of the most promising materials for ultraviolet and blue light-emitting diodes and lasers. Both Molecular Beam Epitaxy (MBE) and Metal-Organic Chemical Vapor Deposition (MOCVD) have recently made strong progress in fabricating high-quality epitaxial GaN thin films. In this paper, we review materials-related issues involved in MBE growth. We show that a strong understanding of the unique meta-stable growth process allows us to correctly predict the optimum conditions for epitaxial GaN growth. The resulting structural, electronic and optical properties of the GaN films are described in detail.

}, author = {Nathan Newman and T.C. Fu and Z. Liu and Zuzanna Liliental-Weber and Michael D. Rubin and James S. Chan and Erin C. Jones and Jennifer T. Ross and Ian M. Tidswell and Kin Man Yu and Nathan W. Cheung and Eicke R. Weber} } @conference {12084, title = {Modeling Windows in DOE 2.1E}, booktitle = {Thermal Performance of the Exterior Envelopes of Buildings V Conference}, year = {1994}, month = {12/1992}, address = {Clearwater Beach, FL}, abstract = {

The most recent version of the DOE-2 building energy simulation program, DOE-2.1E, provides for more detailed modeling of the thermal and optical properties of windows. The window calculations account for the temperature effects on U-value, and update the incident angle correlations for the solar heat gain properties and visible transmittance. Initial studies show up to a 30\% difference in calculating peak solar heat gain between the detailed approach and a constant shading-coefficient approach. The modeling approach is adapted from Lawrence Berkeley Laboratorys WINDOW 4 computer program, which is used in the National Fenestration Rating Council (NFRC) U-value rating procedure 100-91. This gives DOE-2.1E the capability to assess the annual and peak energy performance of windows consistent with the NFRC procedure. The program has an extensive window library and algorithms for simulating switchable glazings. The program also accounts for the influence of framing elements on the heat transfer and solar heat gain through the window.

}, author = {M. Susan Reilly and Frederick C. Winkelmann and Dariush K. Arasteh and William L. Carroll} } @conference {12105, title = {A New Method for Predicting the Solar Heat Gain of Complex Fenestration Systems}, booktitle = {Thermal Performance of the Exterior Envelope of Buildings V Conference Proceedings}, year = {1992}, month = {12/1992}, address = {Clearwater Beach, FL}, abstract = {

A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure the bi-directional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorptances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient.

The method has been applied to one of the most optically complex systems in common use, a venetian blind in combination with multiple glazings. A comparison between the scanner-based calculation method and direct system calorimetric measurements made on the LBL MoWiTT facility showed good agreement, and is a significant validation of the method accuracy and feasibility.

}, author = {Joseph H. Klems and Jeffrey L. Warner} } @techreport {1724, title = {Photoelectric Control of Daylight-Following Lighting Systems}, year = {1989}, month = {02/1989}, abstract = {

The ability of daylight-following lighting systems to provide a minimum specified light level at the task surface is influenced by 1) the control algorithm used, 2) the spatial response of the ceiling-mounted control photosensor and 3) the location of the photosensor relative to task and window. Best performance was obtained with a closed-loop proportional control system controlled by a photosensor, with a large field of view but shielded from direct light from the window. A minimum specified illuminance level could be maintained at specific points on the task surface regardless of daylight condition or room geometry provided that the system gain was properly calibrated to account for the local luminous environment.

Open-loop proportional control also performed adequately but offered less precise control than closed-loop systems due to the necessity of using a photosensor that was not shielded from direct window light. Integral-reset systems that were tested performed poorly, but performance could be improved slightly by completely shielding the photocell from direct window light.

}, author = {Francis M. Rubinstein and Rudolph R. Verderber and Gregory J. Ward} } @conference {11992, title = {The Integration of Operable Shading Systems and Lighting Controls}, booktitle = {International Daylighting Conference Proceedings}, year = {1986}, month = {11/1986}, address = {Long Beach, CA}, abstract = {

Using daylighting in commercial buildings may significantly reduce electric lighting requirements if appropriatesphotoelectric controls are used to adjust the electric lighting output according to the available daylight. Prior analysis andsresults from monitored buildings and scale-model measurements suggest that the selection, placement, and installation ofsthe control photosensor is a difficult task, even with simple non-operable fenestration systems, since the daylightscontributions from sun, sky, and ground change continuously. The problem becomes even more complex forsfenestration systems that incorporate operable shading devices, because every adjustment changes the systems opticalsproperties. This paper presents results from measurements in a scale model under real skies, designed to bettersunderstand the problem of integrating fenestration and lighting controls. The scale model represented a typical officesspace and was equipped with motorized venetian blinds. Three control photosensors mounted on the ceiling weresconsidered for the operation of the electric lighting system, and two control strategies were considered for the operation ofsthe venetian blinds. Two ground-plane reflectances and two window orientations were examined. Results indicate thatsthe signal from a ceiling-mounted control photosensor shielded from direct light from the window shows the bestscorrelation with daylight work-plane illuminance, regardless of ground plane reflectance or venetian blind slat angle for allsslat angles that do not allow penetration of direct solar radiation. Results also indicate that the control strategies of thesvenetian blinds that were considered for the purposes of this study may result in significantly different slat angles, andsthus different daylighting work-plane illuminances and electric lighting requirements, especially when the ground-planesreflectance is high.

}, author = {Konstantinos M. Papamichael and Francis M. Rubinstein and Stephen E. Selkowitz and Gregory J. Ward} }