Our Company

History

Thermal Energy System Specialists (TESS) was founded in the spring of 1994 by Jeff Thornton and Alexander Fiksel. At the time, Jeff was working at the University of Wisconsin Solar Energy Laboratory as the coordinator of the international TRNSYS development team and Alex was a programmer for the software package. Through his work at the University, Jeff had become increasingly aware that TRNSYS was not only a powerful research tool but a simulation package ideally suited to perform in-depth analyses of innovative energy systems and buildings that other more commonly-used software packages could not address. Jeff and Alex founded TESS with the dual purpose of continuing to develop TRNSYS and providing consulting services to the building energy community. Alex chose to leave the company in 1995 to pursue more programming-driven opportunities and Tim McDowell joined shortly thereafter. Nathan Blair worked at TESS as the TRNSYS Coordinator from 1998 to 1999 before leaving to pursue an MBA. David Bradley joined TESS in 2001 as TRNSYS Coordinator and became a partner in 2004. Matthew Duffy was TRNSYS Coordinator from 2008 to 2012. Angela Weiss joined in 2010 as a project engineer.

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Jeff W. Thornton

Jeff founded TESS in 1994 and currently serves as President.  He has a Bachelor of Science and a Master of Science degree in mechanical engineering from the University of Wisconsin.  He is a former technical coordinator of the TRNSYS program at the Solar Energy Laboratory at the University of Wisconsin and has a strong background in energy system design and modeling.  While at TESS, Jeff has spearheaded numerous modeling and simulation projects from small-scale residential analyses to multi-million dollar, community-sized ventures.

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Timothy P. McDowell

Timothy joined TESS in 1995 after a stint in the HVAC design field and currently serves as the Vice President.  He has a Bachelor of Science degree in mechanical engineering from Rice University and a Master of Science degree in mechanical engineering from the University of Wisconsin.  Tim specializes in engineering software development and maintains a very active role in the national modeling community.

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David E. Bradley

David joined TESS in 2001 after serving as the technical coordinator of the TRNSYS program at the University of Wisconsin.  He has a Bachelor of Science degree in engineering from Swarthmore College and a Master of Science degree in mechanical engineering from the University of Wisconsin.  David has served as principal investigator on numerous energy modeling projects and serves as the liaison to the international TRNSYS development community.

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Angela M. Weiss

Angela joined TESS in October of 2010 after several years working for an energy efficiency consulting firm. She holds a Bachelor of Science degree in mechanical engineering from Iowa State University and a Master of Science degree in mechanical engineering from the University of Wisconsin-Madison. Her research work, completed through the UW-Madison's Solar Energy Laboratory, includes TRNSYS simulations and performance evaluations for parabolic trough solar power plants. Other past work experience includes simulations and annual energy performance evaluations for solar domestic hot water systems, industrial ammonia refrigeration systems, and commercial HVAC applications.