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Residential Buildings Research Staff

Members of the Residential Buildings research staff have backgrounds in architectural, civil, electrical, environmental, and mechanical engineering, as well as environmental design and physics.

Support Staff

Photo of Dennis Barley

C. Dennis Barley — Senior Engineer

Ph.D. Mechanical Engineering, Colorado State University
M.S. Mechanical Engineering, Colorado State University
B.S. Electrical Engineering, Drexel University

Dennis joined NREL in 2001. His primary research areas are energy use in buildings, analysis methods, model development, and lab and field testing. Dennis is adding capabilities to the BEopt residential buildings simulation and optimization tool, and characterizing the existing U.S. housing stock for retrofit analysis.

Prior to joining NREL, Dennis coauthored the Passive Solar Design Handbook at LANL and coded early solar heating design software for handheld calculators.

Contact information: dennis.barley@nrel.gov, 303-384-7592

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Photo of Chuck Booten

Chuck Booten — Senior Engineer

Ph.D. Mechanical Engineering, Stanford University
M.S. Mechanical Engineering, Massachusetts Institute of Technology
B.S. Mechanical Engineering, Massachusetts Institute of Technology

Chuck joined NREL in 2010. His research is focused on heat transfer modeling and the study of home energy management system performance. Chuck is also involved in DOE Building America research coordination.

Prior to working at NREL, Chuck was a project manager at Protonex Technology, where he directed the development of kilowatt-scale solid-oxide fuel cell systems for both military and civilian customers. His background is in experimental heat transfer and fluid mechanics.

Contact information: chuck.booten@nrel.gov, 303-275-3167

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Photo of Craig Christensen

Craig Christensen — Senior Engineer

M.S. Mechanical Engineering, Brigham Young University
B.S. Mechanical Engineering, Brigham Young University

Craig joined NREL in 1979. He leads the energy analysis efforts for the Building America Program and supports solar buildings research efforts at NREL that includes BEopt development, analysis for new and existing residential buildings, and modeling accuracy. Craig has also led many projects related to residential and commercial buildings, active solar systems, passive solar design, energy conservation, and computer modeling of buildings, systems, and components. He originated the concept of the unglazed transpired solar collector at NREL and participated in research that led to an R&D 100 Award and Popular Science "Best of What's New" Award in 1994.

Prior to joining NREL, Craig worked as a solar consultant, individually and at a small mechanical engineering firm. He also worked for three years for the National Oceanic and Atmospheric Administration as a scientist and officer on oceanographic ships.

Contact information: craig.christensen@nrel.gov, 303-384-7510

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Photo of Dane Christensen

Dane Christensen — Senior Engineer

Ph.D. Mechanical Engineering, University of California-Berkeley
B.S. Mechanical Engineering, Rice University

Dane joined NREL in 2008 with a background in equipment testing and integration. He manages the Residential Building Group’s laboratory work and coordinates research on advanced heating, ventilating, and air conditioning (HVAC) systems. This work addresses technology gaps for healthy, durable and energy-efficient homes and provides data to improve high-performance building simulation. Dane supports technical efforts for the Building America Program and conducts finite element modeling for building energy simulation.

Prior to joining NREL, Dane worked at Atec, designing test and support equipment for turboshaft engines.

Contact information: dane.christensen@nrel.gov, 303-384-7437

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Photo of Lieko Earle

Lieko Earle — Senior Engineer

Ph.D. Physics, University of Colorado at Boulder
B.S. Physics, Brown University

Lieko joined NREL in 2009. She leads the field testing efforts for the Building America Program. Her research focuses on developing field testing and analysis methods to identify gaps and barriers for emerging and advanced retrofit systems to be implemented on a broad basis, as well as field evaluations of innovative building envelopes, water heating, and heating, ventilating, and air conditioning (HVAC) systems. She also conducts laboratory- and field-based investigations of automated home energy management (AHEM) devices, Non-Intrusive Load Monitoring (NILM) techniques, and control strategies to develop cost-effective systems that integrate smoothly with home area networks and smart grids to maximize source energy savings.

Lieko's background is in astrophysics instrumentation and extragalactic spectroscopy. Prior to graduate school she taught physics as a Peace Corps volunteer in Tanzania, where she spent many happy hours devising laboratory experiments for students using locally available materials.

Contact information: lieko.earle@nrel.gov, 303-275-4355

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Photo of Mike Heaney

Mike Heaney — Research Analyst

Ph.D. Chemical Engineering, University of Colorado at Boulder
M.S. Chemical Engineering, University of Colorado at Boulder
B.S. Chemical Engineering with Honors, Montana State University

Mike joined NREL in 2011. He supports the software accuracy efforts by applying statistical analysis to data collected in the Building America Field Data Repository (BAFDR). He is also involved in quantifying retrofit benefits and studying how energy use varies with occupant behavior using data collected from ongoing field tests.

Prior to joining NREL, Mike worked at various positions requiring extensive use of advanced statistical methods applied to customer and transactional data. He first learned and applied a variety of statistical methods to improving laboratory measurements and chemical processes during his 11 years working for The Dow Chemical Company.

Contact information: michael.heaney@nrel.gov, 303-275-3883

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Photo of Scott Horowitz

Scott Horowitz — Senior Engineer

M.S. Civil Engineering, University of Colorado at Boulder
B.S. Mechanical Engineering, Rutgers University

Scott joined NREL in 2007 and leads the Residential Building Group’s analysis area, which includes work on building energy modeling, optimization, accuracy, and technology pathways. He is also the lead developer of BEopt, a residential building energy optimization tool used to provide support for the Building America program’s teams and energy-efficiency goals.

Prior to joining NREL full time, Scott spent four years at NREL as a University of Colorado graduate student exploring enhancements to building optimization in terms of robustness and efficiency, and he was a member of the 1st place University of Colorado Solar Decathlon team.

Contact information: scott.horowitz@nrel.gov, 303-384-7560

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Photo of Jeff Maguire

Jeff Maguire — Engineer

M.S. Mechanical Engineering, University of Colorado at Boulder
B.S. Mechanical Engineering, Rensselaer Polytechnic Institute

Jeff joined NREL in 2012 after working as a graduate student since 2010. His research focuses on the modeling and performance analysis of residential water heaters, analyzing data from field test studies of several water heaters, developing models of new water heating technologies, and performing simulations to determine the impact of use and climate on water heater efficiency. Jeff specializes in component modeling and performance analysis.

Contact information: jeff.maguire@nrel.gov, 303-275-4309

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Photo of Noel Merket

Noel Merket — Engineer

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

Noel joined NREL in 2010. His work at NREL includes the National Residential Efficiency Measures Database, Field Data Repository, and building energy optimization software development. His prior research experience was on two-phase liquid vapor heat transfer for thermal management of small satellites.

Contact information: noel.merket@nrel.gov, 303-275-3156

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Photo of Tim Merrigan

Tim Merrigan — Senior Project Leader

M.S. Mechanical Engineering, University of Central Florida
B.S. Mechanical Engineering, Columbia University
B.A. Physics, Rollins College

Tim joined NREL in 1999. His research focuses on solar water heating technology development, PV/thermal system development and demonstration, and integrated solar heating and cooling systems.

Prior to joining NREL, Tim was with the Florida Solar Energy Center for 20 years, conducting research in solar thermal systems and building energy efficiency. Tim served as the chair of the ASHRAE Technical Committee for Solar Energy Utilization, served as the chair of the Standards Committee for the Solar Rating & Certification Corporation (SRCC), and was on the Board of Directors for the Colorado Solar Energy Industries Association (COSEIA).

Contact information: tim.merrigan@nrel.gov, 303-384-7349

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Photo of Ben Polly

Ben Polly — Senior Engineer

M.S. Engineering Mechanics, University of Nebraska-Lincoln
B.S. Mechanical Engineering, University of Nebraska-Lincoln

Ben joined NREL in 2009. He specializes in whole building energy simulation and software validation. His research involves improving the accuracy of building energy simulation software and BEopt retrofit analysis.

His prior research experience includes nanoscale material characterization, biomechanics, vibrations, and continuum mechanics.

Contact information: ben.polly@nrel.gov, 303-384-7429

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Photo of David Roberts

David Roberts — Group Manager and Senior Engineer

M.S. Civil Engineering, University of Colorado
B.S. Environmental Resources Engineering, Humboldt State University

David joined NREL in 2008. David is the Residential Buildings Research Group Manager. He supports DOE research activities including the Building America program.

David has been working in the area of energy efficiency in buildings since 1989 and is a licensed Professional Engineer in Colorado. He has expertise in building science, building energy simulation, and software development. Prior to joining NREL, David worked for Architectural Energy Corporation, where he led energy simulation and software development projects, and served as product manager for the REM/Rate™ home energy rating software.

Contact information: david.roberts@nrel.gov, 303-384-7496

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Photo of Joseph Robertson

Joseph Robertson — Engineer

M.S. Computational and Applied Mathematics, Colorado School of Mines
B.S. Mathematics/Spanish, Marquette University

Joe joined NREL in 2012. His research activities include automated building model calibration and the Field Data Repository. He specializes in building energy simulation, modeling and data analysis, and mathematical optimization.

Joe also worked at NREL for two years as an intern and graduate student from the Colorado School of Mines on projects involving numerical methods applied to uncertainty/sensitivity analysis and automated building model calibration.

Contact information: joseph.robertson@nrel.gov, 303-275-4575

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Photo of Stacey Rothgeb

Stacey Rothgeb — Senior Engineer

B.S. Architectural Engineering, Kansas State University

Stacey joined NREL in 2009. She has a diverse background in engineering design, construction project management, and energy consulting. Stacey is a research coordinator for the Building America Program. Her research efforts include performance testing and analysis for both new and existing homes.

Prior to joining NREL, Stacey worked as the energy manager at the U.S. Air Force Academy. She also owned and operated her own residential energy consulting firm. Stacey is a licensed Professional Engineer (PE) and a Certified Energy Manager (CEM).

Contact information: stacey.rothgeb@nrel.gov, 303-275-4361

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Photo of Bethany Sparn

Bethany Sparn — Senior Engineer

M.S. Mechanical Engineering, Colorado State University
B.S. Mechanical Engineering, Columbia University
B.S. Physics and Mathematics, University of Puget Sound

Bethany joined NREL in 2010. Her research focuses on residential HVAC equipment, heat pump water heaters, non-intrusive load monitoring equipment, automated home energy management devices, and whole-house performance field testing.

Contact information: bethany.sparn@nrel.gov, 303-384-7442

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Eric Wilson

Eric Wilson — Engineer

M.S. Civil Environmental and Architectural Engineering, University of Colorado
B.S. General Engineering, University of Illinois

Eric joined NREL in 2010. He is working on the development of the BEopt software, Building America house simulation protocols, and water heating.

Prior to joining NREL, Eric researched the energy implications of pressure drop in residential duct systems.

Contact information: eric.wilson@nrel.gov, 303-275-4676

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Jon Winkler

Jon Winkler — Senior Engineer

Ph.D. Mechanical Engineering, University of Maryland
B.S. Integrated Science and Technology, James Madison University

Jon joined NREL in 2009. His research focuses on residential HVAC systems, residential dehumidification control, energy modeling tools, and BEopt development.

Prior to working at NREL, Jon was a faculty research assistant in the Mechanical Engineering Department at the University of Maryland, where he co-led the development effort of simulation and optimization software used by HVAC manufacturers.

Contact information: jon.winkler@nrel.gov, 303-275-4356

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Jason Woods

Jason Woods — Senior Engineer

M.S. Mechanical Engineering, University of Colorado
B.S. Mechanical Engineering, Purdue University

Jason joined NREL in 2010 after working there as a doctoral student since 2007. Jason's expertise is in numerical modeling and experiment design for heat and mass transfer processes. His research includes: (1) the development of innovative HVAC processes, such liquid-desiccant-assisted evaporative cooling and membrane-based HVAC processes and (2) the development and analysis of new models for moisture storage and transport in building materials.

Contact information: jason.woods@nrel.gov, 303-384-6189

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Support Staff

Jason Woods

Marcia Fratello — Administrative Associate

Marcia joined NREL in 1999. She supports the group manager, engineers, and researchers in the Residential Buildings Research Group and Building America Program. Prior to joining NREL, Marcia worked as an administrative assistant for more than 25 years at various levels for both small and large companies including American Cyanamid and Johns Manville.

Contact information: marcia.fratello@nrel.gov, 303-384-7440

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Kristy Usnick

Kristy Usnick — Project Administrative Associate

Colorado Mountain College/Pueblo Community College, Business Management
US NAVY Telecommunications Certified

Kristy joined NREL in 2011. She supports the Building America research coordinator team as well as the engineers and researchers in the Residential Buildings Research Group. She is the site administrator for the internal and external SharePoint sites, system administrator for the Editorial Manager National Renewable Energy Laboratory Peer Review System, and manages the Residential Buildings publications in PubHub.

Prior to joining NREL, Kristy worked as an environmental/radiation safety administrative assistant for more than 11 years at a Uranium Milling Facility in Southern Colorado.

Contact information: kristy.usnick@nrel.gov, 303-384-7448

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