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Commercial Buildings Research Staff

Members of the Commercial Buildings research staff have backgrounds in architectural, civil, electrical, environmental, and mechanical engineering, as well as computer science, physics, and chemistry.

Photo of Brian Ball

Brian Ball — Engineer IV

Ph.D., M.S. Computational and Applied Mathematics, North Carolina State University
B.S. Physics, Worcester Polytechnic Institute of Technology
B.S. Mathematics, Worcester Polytechnic Institute of Technology

Brian joined NREL in June 2010. His expertise is in modeling, control and simulation of physical systems as well as numerical analysis and numerical methods. His experience includes solving partial differential equations, nonlinear equations and optimization, multiscale modeling, and control of smart material systems. At NREL, Brian specializes in hardware in the loop simulation at the campus level for the Energy System Integration program, developing inverse modeling algorithms to calibrate building energy models, and is part of the OpenStudio development team. In addition, Brian has worked on several large-scale sector analysis projects, including DOE Asset Score, and helped developed the Cloud computing environment for OpenStudio. Prior to joining NREL, Brian was a simulation engineer for GE Energy modeling power plants and related equipment. This work included developing an engineering grade operator training simulator for an integrated coal gasification combined cycle power plant.

Contact information:, 303-275-4569

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Photo of Kyle Benne

Kyle Benne — Software Developer

M.S. Mechanical Engineering, Missouri University of Science and Technology
B.S. Mechanical Engineering, Missouri University of Science and Technology

Kyle joined NREL in 2007, and works in the Commercial Buildings Research Group as a software developer. He is a member of the OpenStudio development team, where he focuses on creating new simulation tools related to HVAC systems. Prior to joining NREL, Kyle was a graduate researcher and developed expertise in fluid mechanics and numerical simulation.

Contact information:, 303-275-4603

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Photo of Willy Bernal

Willy Bernal — Engineer III

M.S. Electrical Engineering, University of Pennsylvania
M.S. Mechanical Engineering and Applied Mechanics, University of Pennsylvania
B.S. Electrical Engineering, University of Pennsylvania
B.S. Mechanical Engineering and Applied Science, University of Pennsylvania

Willy joined NREL in 2015 with a focus on controls and on co-simulation tools for energy-efficient buildings. He has co-developed MLE+, a co-simulation toolbox for design and deployment of energy-efficient buildings controls. Willy was an intern at NREL, developing the framework to model whole-campus dynamics to coordinate and synchronize its multiple loads.

Prior to joining NREL, Willy was the lead controls engineer for Lit Motors where he focused on developing the controls for a self-balancing two-wheel electrical vehicle.

Contact information:, 303-384-7404

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Photo of Eric Bonnema

Eric Bonnema — Mechanical Engineer

M.S. Mechanical Engineering, Colorado State University
B.S. Mechanical Engineering, Colorado State University

Eric has been at NREL since 2008 and contributes to the research efforts for commercial buildings. This effort is dedicated to studying the behavior of low-energy buildings both on the design side as well as the performance side. Eric is interested in energy modeling of buildings and software development for building optimization and modeling. He research focus includes sector-wide energy modeling, Advanced Energy Design Guides, and the 179D DOE Calculator. He specializes in software development for building optimization and modeling, commercial sector whole-building energy simulation, scientific computing, and software configuration and package management.

Prior to joining NREL, Eric was an applications engineer designing air-cooled steam condensers for coal and combined-cycle power plants. Eric holds a master's degree from Colorado State University specializing in energy and the environment. He is also a registered Engineering Intern in Colorado.

Contact information:, 303-384-6185

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Photo of Larry Brackney

Larry Brackney — Manager

Ph.D. Mechanical Engineering, Purdue University
M.S.M.E., Rose-Hulman Institute of Technology
B.S.M.E., Rose-Hulman Institute of Technology

Dr. Brackney joined NREL in 2009, and works in the Commercial Buildings Research Group as a section manager for Sensors, Controls, and Analysis Tools. He specializes in control and embedded systems design, analysis-led design process, and leads the group's software efforts. Prior to joining NREL, Dr. Brackney taught electrical engineering at the University of Canterbury, and worked extensively in the automotive sector developing combustion and power train controls.

Contact information:, 303-384-7443

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Photo of Michael Deru

Michael Deru — Engineering Manager

B.S. Mechanical Engineering, University of Wyoming
M.S. Mechanical Engineering, Colorado State University
Ph.D. Mechanical Engineering, Colorado State University

Dr. Deru joined NREL in 2000 and manages the Systems Performance section in the Commercial Buildings Research Group at the National Renewable Energy Laboratory. He leads projects on the development and testing of novel HVAC systems, building performance simulations, performance metrics for sustainability, source energy and emissions factors, water, and the U.S. Life Cycle Inventory Database. Dr. Deru received an R&D 100 award in 2005 and is very active within ASHRAE. Prior to joining NREL, Michael worked as a nuclear plant engineer with Westinghouse Electric Corp. supporting the U.S. Naval Nuclear Power program.

Contact information:, 303-384-7503

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Photo of Kristin Field-Macumber

Kristin Field-Macumber — Mechanical Engineer

M.S. Civil, Environmental, and Architectural Engineering, Building Systems Program, University of Colorado at Boulder
B.S. Civil Engineering, University of Texas at Austin
B.A. Sociology/Spanish, Rice University

Kristin joined NREL in January 2009. Her expertise is in collaborating with industry partners to identify feasible energy efficiency strategies and using EnergyPlus computer simulation to evaluate standard energy performance and improve design decisions concerning energy efficiency.

Prior to joining NREL, Kristin worked in consulting for Architectural Energy Corporation in Boulder, Colorado. At AEC, she analyzed a wide variety of commercial buildings types for sustainable design assistance work at each design phase of specific building projects.

Contact information:, 303-384-7376

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Photo of Katherine Fleming

Katherine Fleming — Engineer

Ph.D., M.S. Electrical Engineering, Vanderbilt University
B.S. Computer Engineering, University of Evansville

Katherine joined NREL in 2009. She works on various aspects of database and web application development in the Commercial Buildings Research group. Her projects include the Building Component Library, Building Agent, and Technology Performance Exchange.

Prior to joining NREL, Katherine was pursuing a Ph.D. with a focus on robotics and working as a Web developer and Web accessibility consultant for several organizations.

Contact information:, 303-275-4331

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Photo of Stephen Frank

Stephen Frank — Engineer

Ph.D. Electrical Engineering, Colorado School of Mines
M.S. Engineering, Colorado School of Mines
B.S. Engineering, Messiah College

Steve joined NREL in May 2013 and works in the Commercial Buildings Research Group. Steve's areas of expertise are electric power distribution systems, DC power systems, linear and nonlinear optimization, and energy informatics.

Prior to joining NREL, he completed a Ph.D. at Colorado School of Mines. His dissertation research developed analysis and optimization techniques for maximizing the energy efficiency of electrical distribution systems in commercial buildings using a mixture of AC and DC distribution.

Contact information:, 303-275-4249

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Photo of Luigi Gentile Polese

Luigi Gentile Polese — Senior Engineer

M.S. Electronic Engineering, University of Naples, Italy
B.S. Electronic Engineering, University of Naples, Italy

Luigi joined NREL in 2009. He oversees processes and software development of next-generation whole-building energy modeling, analysis, and simulation tools OpenStudio and EnergyPlus. Recently, he also led projects investigating occupancy sensing and controls, wireless sensors networks for plug load energy monitoring and management, and power distribution systems in buildings.

Luigi has more than 22 years of experience in telecommunications R&D programs with companies including AT&T Bell Laboratories, Lucent Technologies, Siemens, and Avaya, where he held senior technical positions in networking protocol specifications, call control software, and requirements engineering. Mr. Gentile Polese holds three U.S. patents and has two additional patents pending.

Contact information:, 303-275-4362

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Photo of David Goldwasser

David Goldwasser — Software Developer

Master of Construction Management, Washington University, St. Louis, MO
Master of Architecture, Tulane University, New Orleans, LA

David has been a software developer for the National Renewable Energy Laboratory's Buildings Technology Program since 2010. A software developer on the OpenStudio team, he focuses on development, support, testing, training, and creation of energy efficiency measures. He provides insight into architectural workflows related to energy modeling and high performance building design.

Prior to joining NREL, David worked in architectural design, 3D modeling, and interactive media. He consulted for Google on 3D modeling tools and worked in Colorado on sustainable architecture projects. Before moving to Colorado he worked in construction management, architectural design, and started his own interactive media company with a focus on panoramic photography.

Contact information:, 303-275-3785

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Photo of Rob Guglielmetti

Rob Guglielmetti — Engineer III

B.A. Theatre, Rowan University

Rob joined NREL in May of 2009. Rob's areas of expertise are daylighting, physically based lighting simulation, the integration of lighting simulation with whole-building energy simulations, and high dynamic range imaging. He has more than 20 years' experience in applying these talents toward designing pleasanter—and more energy-efficient—built environments

Previously, Rob was a daylighting analyst, designer, and group leader for Architectural Energy Corporation in Boulder, CO. Prior to that he spent many years working at major architectural lighting design firms in New York City, and is a regular lecturer on daylighting, lighting simulation, and high dynamic range imaging. Rob is a member of the board of directors of the International Building Performance Simulation Association, an advisory member of the Illuminating Engineering Society of North America's Daylight Metrics Committee, and an active member on the International Lighting Commission's Technical Committee on Climate-based Daylight Modeling.

Contact information:, 303-275-4319

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Photo of Gregor Henze

Gregor Henze — Joint Professor

Ph.D. Civil Engineering, University of Colorado Boulder
Dipl.Ing. Energy and Process Engineering, Technical University of Berlin
M.S. Mechanical Engineering, Oregon State University

Gregor has held a joint appointment at NREL since 2013. Outside of NREL, he is professor of architectural engineering at the University of Colorado Boulder, where his teaching focuses on thermal sciences fundamentals, mechanical systems design, energy system modeling, building control and automation systems, advanced solar systems, data analysis for energy scientists and engineers, as well as sustainable building design. His research includes model predictive optimal control in buildings, control strategies for mixed-mode buildings, uncertainty quantification of occupant behavior as well as the integration of building energy system operations with the electric grid system. He is a professional mechanical engineer, certified high-performance building design professional (HBDP), member of ASHRAE, fellow of the Renewable and Sustainable Energy Institute, as well as co-founder and chief scientist of QCoefficient, Inc.

Contact information:, 303-384-6408

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Photo of Adam Hirsch

Adam Hirsch — Engineer

Ph.D., University of California, Irvine
A.B., Harvard University

Adam joined NREL in 2009, and works in the Commercial Buildings Research Group as an engineer. He is a working with large American corporations to design, build, and operate buildings that save energy as part of the DOE Commercial Building Partnership. In the past at NREL, he has worked on high-performance building design guide research and zero energy buildings.

Prior to joining NREL, Adam was an atmospheric scientist working at the National Oceanic and Atmospheric Administration and the University of Colorado at Boulder studying the atmospheric budget of radiatively active trace gases.

Contact information:, 303-384-7874

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Photo of Eric Kozubal

Eric Kozubal — Senior Researcher

M.S. Mechanical Engineering, University of Colorado Boulder
B.S. Mechanical Engineering, University of California at Santa Barbara

Eric joined NREL in 2002 and is a member of the Commercial Buildings Research Group. Eric researches new methods and technologies for energy-efficient air conditioning systems. He has tested more than 25 HVAC components and systems, including direct expansion, evaporative, and desiccant technologies. He improves manufacturers' products by providing detailed performance, analysis, and design recommendations. He uses tools such as CAD, Matlab, Engineer Equation Solver, Excel, and statistical software to design new HVAC systems, such as the desiccant enhanced evaporative cooling concept. He has also worked to optimize hybrid air- and water-cooled geothermal binary power cycles.

Before joining NREL, Eric developed new flow control products for Emerson Process Management and was a test and manufacturing engineer for a hard disc drive component manufacturer (Now Western Digital Corporation). He is an active member of ASHRAE's technical committees for desiccant and evaporative cooling and has co-authored test standards in these areas.

Contact information:, 303-384-6155

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Photo of Feitau Kung

Feitau Kung — Engineer

M.A. Teaching, Cornell University
B.S. Mechanical Engineering, Cornell University

Feitau Kung joined NREL in 2009. His projects have included producing guidance for evaluating building system energy performance in commercial settings, such as office, healthcare, higher education, and retail facilities. He also examines the impacts of integrating building loads with energy storage and generation. Prior to joining NREL, Feitau worked for Princeton Energy Systems where he assessed the technical and economic feasibility of lighting, HVAC, solar photovoltaic, solar thermal, and small wind system measures, and he assisted facility management staff with sustainable energy planning. He also worked for the U.S. General Services Administration's Public Buildings Service.

Contact information:, 303-275-4357

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Photo of Rois Langner

Rois Langner — Mechanical Engineer

M.S. Civil Engineering, University of Colorado at Boulder
B.A. Physics, Colorado College

Rois Langner has worked as a mechanical engineer in the Commercial Buildings Research Group at NREL since 2010. Her research efforts have focused on building energy efficiency projects that utilize EnergyPlus and OpenStudio software to analyze and optimize building design and performance for military and large commercial buildings. She has also worked with organizations to develop, implement, and maintain energy management policies and systems for continual energy improvement, and more recently is working to support the small commercial building sector in improving building performance.

Contact information:, 303-275-4329

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Photo of Edwin Lee

Edwin Lee — Engineer

Ph.D. Mechanical Engineering, Oklahoma State University

Edwin Lee joined NREL in 2013 and works in the Commercial Buildings Research Group. He manages technical development of EnergyPlus, including maintenance and implementing new features. He also supports NREL's Technology Portal project.

Prior to joining NREL, Edwin was a doctoral candidate at Oklahoma State University. His expertise is primarily in the fields of building simulation tool development and ground heat transfer modeling.

Contact information:, 303-275-3110

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Photo of William Livingood

William Livingood — Group Manager

M.S. Mechanical Engineering, University of California, Irvine
M.S. Chemistry, University of Nevada-Reno
B.S. Chemistry, Shippensburg University of Pennsylvania

Bill is an expert in building energy analysis, computational thermal analysis, and data acquisition and an inventor on three patents for power generation technologies. As manager of the commercial buildings research team, he oversees the development of next generation simulation capabilities and guidance documents such as the Advanced Energy Design Guides (AEDG) that provide building- and U.S. climate zone-specific design recommendations.

Bill comes to NREL from GE Global Research, where he performed thermodynamic, fluid mechanics, and heat transfer analyses to predict system performance of power generation technologies. He also conducted economic analyses to assess power generation system capital costs and developed energy systems computer models. Prior to GE, Bill was with FuelCell Energy where he was part of a team that ensured the success of the launch of large stationary fuel cell products and technologies.

Contact information:, 303-384-7490

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Photo of Nicholas Long

Nicholas Long — Senior Engineer

B.S. Engineering, Colorado School of Mines

Nicholas joined NREL in 2003 and works in the Commercial Buildings Research Group. He is a technical lead on various projects including the Building Component Library and Building Agent. He is an expert in managing, mining, and analyzing building data. He is also an expert in building energy modeling with OpenStudio/EnergyPlus and using the engines for large-scale analyses using high-performance computing to evaluate commercial buildings.

Prior to joining NREL, Nicholas was an NREL intern and student.

Contact information:, 303-384-6183

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Photo of Daniel Macumber

Daniel Macumber — Engineer

M.S. Mechanical Engineering, Massachusetts Institute of Technology
B.S. Mechanical Engineering, University of Colorado, Boulder

Daniel joined NREL in 2008 and works in the Commercial Buildings Research Group. He is a core developer on the OpenStudio project focusing on geometry and interoperability.

Prior to joining NREL, Daniel worked as a software developer working on algorithms for tracking small targets.

Contact information:, 303-384-6172

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Photo of Andrew Parker

Andrew Parker — Engineer

B.S. Textile Engineering, North Carolina State University

Andrew joined NREL in 2010, and his goal is to help make high-efficiency building design commonplace by making existing energy analysis tools more accessible. He works closely with the OpenStudio development team, focusing on product design and the needs of industry. He also works with utilities and third-party companies who are using the tools developed by the commercial buildings research group. Andrew is interested in the improvement of software for the energy auditing space, and was the project manager for a large Department of Defense ESTCP project, working with a third-party company to develop and demonstrate a mobile energy auditing tool.

Contact information:, 303-275-4568

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Photo of Anya Petersen

Anya Petersen — Software Developer

M.S. Applied Mathematics, University of Arizona
B.A. Computer Science, New York University

Anya joined NREL in 2011 as a contractor and was hired by the Commercial Buildings Research Group in 2013. She specializes in Web application architecture and software design patterns. Anya has more than a decade of programming experience, working across many frameworks and languages.

Prior to coming to NREL, Anya developed custom business applications for a New York City-based technology firm.

Contact information:, 303-275-4598

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Photo of Shanti Pless

Shanti Pless — Senior Research Engineer

B.S. Mechanical Engineering, Alfred University

Shanti joined the Commercial Building Research Group at NREL in 1999 with a focus on applied research and design processes for commercial building energy efficiency and building integrated renewable energy. This work has included facilitating numerous integrated design processes and energy modeling teams needed to realize cost-effective zero-energy commercial buildings. He isleading the development of the next round of Advanced Energy Design Guides and managing the Whole Buildings Systems Integration section of the group.

Shanti has written more than 50 journal articles, industry publications, guidebooks, and technical reports related to energy efficiency and zero-energy buildings, with frequent national keynote speaking experience at industry conferences such as Greenbuild, AIA, and ASHRAE. He was awarded an ASHRAE Technology Award in 2013 for NREL's large-scale zero-energy Research Support Facility.

Contact information:, 303-384-6365

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Photo of Jennifer Scheib

Jennifer Scheib — Engineer

M.S. Civil Engineering, University of Colorado, Boulder
B.S. Architectural Engineering, University of Colorado, Boulder

Jennifer joined NREL in 2009 and works in the Commercial Buildings Research Group as a lighting engineer. She is working on daylighting application and occupant behavior research projects that help owners and operators realize zero energy in building operation.

Previously, she was part of the Daylighting Analysis Group at Architectural Energy Corporation in Boulder, Colorado, where she took part in the development of Sensor Placement + Optimization Tool, which won LightFair's Most Innovative Product of the Year in 2008.

Contact information:, 303-275-4323

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Photo of Marjorie Scott

Marjorie Schott — Project Leader

B.S. Biological Sciences, University of Northern Colorado

Marjorie began working at NREL in 2001. She has been a member of the Commercial Buildings Research Group since 2010. Her role involves workflow analysis, information visualization, and interface design for software tools and Web applications. Collaborating closely with the team and users, she helps to provide a vision for the evolution of software interfaces. Marjorie designs OpenStudio, ParametricAnalysisTool, and the Building Agent application interfaces. She also works on Web applications, including Technology Performance Exchange, Building Component Library, Model Maker, EDAPT, and building data visualization design for Building Agent and the Research Support Facility Dashboard.

Prior to joining NREL, Marjorie worked on scientific and technical design with companies including the University of Denver, University of Colorado Health Sciences Center, and several biotechnology companies.

Contact information:, 303-275-3913

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Daniel Studer

Daniel Studer — Engineer III

M.S. Civil Engineering, University of Colorado
B.S. Aerospace Engineering, University of Arizona

Daniel joined NREL in 2009. As a member of the Commercial Buildings Research Group, he has focused on the development and novel execution of whole-building energy simulations using EnergyPlus to identify large-scale areas for reducing and optimizing commercial building energy consumption. Recently, Daniel led NREL's commercial building workforce development efforts and he is leading the development of NREL's Technology Performance Exchange.

Prior to joining NREL, Daniel developed and ran whole-building energy simulations for the Energy Analysis Group at Architectural Energy Corporation in Boulder, Colorado.

Contact information:, 303-275-4368

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Alex Swindler

Alex Swindler — Engineer II

B.S. Computer Science, University of Virginia

Alex joined NREL in February 2011. His educational background includes distributed computing, Web information systems engineering, software engineering, computer graphics, and engineering business. At NREL, Alex worked to develop, build, and test the OpenStudio energy simulation suite, the Building Component Library, Image Processing Occupancy Sensor, Research Support Facility Energy Dashboard, NREL Energy Story visualization, Green Button data integration, as well as a large number of Web interfaces, dashboards, databases, and distributed simulations to support energy analysis for commercial buildings. Alex compiles and tests cross-platform iteration and release builds of OpenStudio, adds functionality, resolves bugs, and maintaining the continuous integration dashboard. Alex is also the recipient of an R&D 100 Award.

Prior to joining NREL, Alex worked as a system administrator, Web developer, and Unity developer for a full-service mechanical, electrical, structural, and energy-engineering firm.

Contact information:, 303-275-3265

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Photo of Paul Torcellini

Paul Torcellini — Principal Engineer

Ph.D. Mechanical Engineering, Purdue University
M.S. Mechanical Engineering, Purdue University
B.S. Mechanical Engineering, Worcester Polytechnic Institute

Paul is the principal engineer for the Commercial Buildings Research Group and has been at the NREL for 19 years. Prior to this role, he was the group manager for the Commercial Buildings Research team. He also spent three years as a technical advisor to the U.S. Department of Energy in Washington, D.C. Paul was an instrumental part creating the process to achieve the Zero Energy Building status for NREL's Research Support Facility.

Paul has authored or co-authored more than 50 papers and articles related to energy efficiency and zero-energy commercial buildings. Among his many awards, Paul has received two ASHRAE Technology Awards for his energy-efficient buildings work and two Energy User News magazine's Efficient Building Awards. Paul has been key in the development of the Advanced Energy Design Guide series from ASHRAE and has chaired two of the guides for K-12 schools and grocery stores.

He has also been an adjunct faculty member at Colorado School of Mines and the University of Denver. He is a registered professional engineer.

Contact information:, 303-384-7528

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Photo of Kim Trenbath

Kim Trenbath — Project and Research Quality Analyst

Ph.D. Atmospheric Science, University of Colorado
M.S. Industrial Engineering, West Virginia University
B.E. Civil and Environmental Engineering, Vanderbilt University

Kim conducts project and program management for the Commercial Buildings Research Group. She manages the group's finances and leads business development efforts.

Prior to joining NREL, Kim worked as an analyst in global power strategic sourcing, risk management, and wind energy business development. Her prior research involves in-cabin air quality, science understanding, and break-in training.

Contact information:, 303-275-3710

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Evan Weaver

Evan Weaver — Engineer III

B.S. Mechanical Engineering, Colorado State University

Evan joined NREL in 2010. As a member of the Commercial Buildings Research Group, he works as a software engineer developing whole-building energy modeling tools.

Prior to joining NREL, he worked in the biomedical industry as a software engineer, specializing in graphical user interface and algorithm development. He also worked as an engineer in power generation prime mover controls.

Contact information:, 303-275-3909

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