Petersen Engineering is a mechanical engineering consulting firm specializing in building mechanical systems, energy efficiency, integrated design, sustainable and green design.
James Petersen
James began his career in this industry in 1986 and founded Petersen Engineering, Inc. in 1992.
Passionate about energy and the environment, James has expanded his expertise from his roots in HVAC and plumbing design to include building science, enclosure design and integrated design.
A broad view of buildings, energy, and the environment has significantly changed James’ practice. The success of the sustainable design movement has created new opportunities and has elevated his role on projects as the mechanical engineer. James participates on project teams that successfully integrate the experience and expertise of all project team members that results in high-performance buildings.
James is a registered Professional Engineer in New Hampshire (#8139), Massachusetts (#36560) and Maine (#7231) and is a LEED® Accredited Professional. He received a Bachelor of Science in Mechanical Engineering and a Bachelor of Arts in Philosophy from the University of New Hampshire.
James Parkington
James began his consulting mechanical engineering career in 1999 with Randall Lamb San Francisco. He returned to New England in 2006, working for RFS Engineering for nearly two years before joining Petersen Engineering in November 2007. He has significant experience with the design and implementation of mechanical systems for laboratories, research facilities, hospitals, clinics, theaters, colleges and universities, and high-rise structures.
James is committed to the sustainable, efficient and economical design of mechanical systems, with a particular interest in control strategies that allow building systems to react dynamically to occupant needs.
James provides project management and high level engineering for a variety of project types. Conceptual reports, basis of design documentation, specifications, control sequences, flow diagrams and on-site evaluations are just a few of the services that James provides as a “hands on” project engineer.
James received his Bachelor of Science degree in Mechanical Engineering from the University of New Hampshire in 1997. He is a Registered Professional Engineer in New Hampshire, Massachusetts, and California and a LEED® Accredited Professional.
Sarah Carter
Sarah began her consulting mechanical engineering career in 2004 with Jacobs Engineering in Washington, DC. She returned to New England and joined Petersen Engineering in the fall of 2009. She has experience with the HVAC design of large government facilities such as: battle command training centers, maintenance facilities, laboratories, office buildings, data/command centers and military training campuses.
Sarah has developed a strong interest in highly efficient mechanical systems. This interest was inspired through her extensive energy modeling experience. She is also looking to expand her knowledge in building science, specifically high performance building enclosures.
Sarah offers engineering design skills within all aspects of the design process for many building types. Sarah also plans to take a leading role in implementing 3D Building Information Modeling into the design process at Petersen Engineering.
Sarah received her Bachelor of Science degree in Mechanical Engineering from the University of Vermont in 2003. She is a Registered Professional Engineer in New Hampshire and Virginia, a Construction Documents Technologist (CDT), and a LEED® Accredited Professional.
Scott Hening
Scott began his career in mechanical engineering in 1992 with Yeaton Associates in Littleton, NH. In 2009, Scott opened and ran his own mechanical engineering and energy consulting firm, Hening Energy Strategies, until joining Petersen Engineering in March of 2010.
Highly motivated by energy and environmental issues, Scott is committed to designing energy efficient, sustainable and durable mechanical systems. Scott’s engineering and project management experience covers a broad range of facility types, including schools, office buildings, retirement homes, manufacturing, and science centers. He also has experience with many types of university and health care facilities. In addition, Scott has gained a high level of proficiency in energy modeling and has completed energy models for several projects seeking LEED® certification.
As a mechanical engineer and project manager, Scott enjoys seeing a project through from “kick-off” to completion. Scott participates in all aspects of project development, with duties that typically include: meeting with clients to review and develop project scope and budget, system selection and design, load calculations and energy modeling, equipment selection and specification, project specifications, control sequences, site investigations and system evaluations, trouble-shooting and performance verification.
Scott is a licensed Professional Engineer in the states of Maine, New Hampshire and Vermont, a LEED® Accredited Professional and Certified Energy Manager (CEM). He received Bachelor of Science and Master of Science degrees in Mechanical Engineering from the University of New Hampshire in 1986 and 1990, respectively, graduating Summa Cum Laude.
Outside of work, Scott enjoys outdoor activities such as hiking, biking and cross-country skiing.
Ryan Lacey
Ryan came to Petersen Engineering as an intern in June 2007 and joined the team full time in August 2007.
Ryan discovered his niche in high performance green buildings during his collegiate studies and while attending the Build Boston, NESEA and Efficiently Vermont building conferences. Since discovering his passion, Ryan has strived to expand his knowledge of buildings from all engineering perspectives and to apply a holistic approach to the modeling and design of building systems.
At Petersen Engineering, Ryan continues to pursue his interest in high performance buildings. He enjoys the juxtaposition of calculations associated with the designing of a successful high performance building and its form, shape and design. Detailed energy modeling and the performance of heating and cooling load calculations has given Ryan a solid foundation and understanding of the components of a building’s annual energy use.
Ryan graduated Summa Cum Laude from Keene State College in 2007 with a Bachelor of Science in Architecture.
Aubrey Gewehr
Aubrey came to Petersen Engineering as an engineering intern for the summer of 2006 and joined the team full time upon graduation from college in April, 2007.
Prior to a career in consulting engineering, Aubrey worked in the construction field for many years as a finish carpenter and cabinet maker. His strong environmental ethic caused him to seek opportunities in the field of renewable energy and led him back to school as an adult re-entry college student. Aubrey believes strongly in the integrated design process for creating well designed sustainable buildings that combine beauty and functionality with a light touch on the environment. He has a particular interest in highly efficient heating, cooling and ventilation systems that utilize renewable energy sources wherever feasible.
At Petersen Engineering Aubrey enjoys the detailed planning work involved in evolving a project from concept to completion. Designing efficient air and hydronic distribution systems, calculating thermal loads and analyzing ventilation requirements represent a few of the detailed functions that Aubrey provides.
Aubrey is a registered Engineer in Training (E.I.T.) in New Hampshire and a LEED® Accredited Professional. He received a Bachelor of Science degree in Mechanical Engineering from California Polytechnic State University, San Luis Obispo where he graduated Magna Cum Laude in 2007.
Emily Knowlton
Emily takes care of bookkeeping and other office management tasks at Petersen Engineering on a part-time basis and is also a full-time student. Emily hopes that the small business experience she is gaining at Petersen Engineering will help her manage her own small business someday.
Emily graduated from the University of New Hampshire in 2009 with a major in Speech Pathology and a minor in Business Administration. She is currently persuing a master’s degree in Speech Pathology.

