About

James Freihaut is a Professor in the Department of Architectural Engineering at Penn State University. His research areas include building mechanical systems with a focus on indoor air quality and building science, combined heat and power systems, distributed energy systems, and enclosed space air quality issues. His expertise encompasses system constraints on air treatment and filtration solutions, contributing to the development of high-performing and sustainable building environments. Freihaut holds a Master of Science in Physical Chemistry from Rensselaer Polytechnic University (1972) and a Ph.D. in Fuel Science from Penn State University (1980). His work has significantly advanced understanding in areas such as aerosol science, indoor particle resuspension, energy performance of HVAC systems, and ultraviolet inactivation of airborne microorganisms. He has contributed to the field through numerous publications, including journal articles, conference proceedings, and manuscripts, emphasizing the scientific and engineering aspects of planning, designing, and constructing buildings. His research supports Penn State's mission to lead in innovative education and research aimed at achieving high-performing built environments.

Research topics

• Computer Science
• Engineering
• Computer Security
• Automotive engineering
• Data Mining
• Artificial Intelligence
• Algorithm
• Reliability engineering
• Real-time computing
• Telecommunications
• Computer network
• Electrical engineering

Selected publications

• Energy dispatch optimization at Controlled Environment Agriculture sites with CHP: How energy utilization, storage, and market exports impact operational costs

  Energy Conversion and Management · 2025-04-02 · 10 citations

  articleOpen accessSenior author
  PublisherOA PDFDOI

• From comparison to integration: Building energy simulation tool variability and the case for intelligent retrofit workflows

  Energy Reports · 2025-12-13

  articleOpen accessSenior author

  As the urgency to address climate change and modernize energy infrastructure grows, the building sector plays a key role in improving energy efficiency and reducing carbon emissions. This study evaluates five energy retrofit strategies for Building 101 at The Navy Yard in Philadelphia, comparing two real-world proposals from energy service companies with three simulation-based packages derived from Building Energy Simulation (BES) tools. The study examined whether advanced BES tools provide greater accuracy and decision-making value compared to simpler alternatives. Electricity savings ranged from 5 % to 40 %, gas savings from 29.7 % to 61 %, and annual cost reductions between $22,495 and $55,383. The most effective package achieved a 40 % reduction in energy use, with a simple payback of 2.8 years, demonstrating strong economic and environmental viability. By directly comparing retrofit outcomes across five independently developed scenarios, each using distinct software, data inputs, and calibration protocols, this study uniquely captures the fragmented reality of energy modeling practice and provides a scalable framework for cross-tool benchmarking. Advanced BES tools produced more detailed outputs but require significant expertise and data, while simpler platforms like Asset Score produced comparable results with lower input demands, making them suitable for early-stage or resource-constrained assessments. The study’s direct comparison across divergent baselines reveals how tool selection influences both technical outcomes and retrofit feasibility. Future research should prioritize AI-driven calibration, digital twins, and adaptive modeling to enhance accuracy, reduce complexity, and support scalable, stakeholder-responsive retrofit planning. • Evaluated 5 EEM packages for Building 101's energy retrofit. • Compared real-world data with simulation outputs from multiple BES tools. • Showcased Asset Score's viability against more complex BES tools. • Highlighted economic impacts of energy retrofitting on projected savings. • Identified need for AI-driven tools in future BES research.

  PublisherDOI

• Developing a Robust Market for CHP: A Plan for Fostering Economic Development, Business Competitiveness and Resiliency in the Mid-Atlantic Region

  2024-07-31

  reportOpen accessSenior author

  The Department of Energy’s Mid Atlantic Combined Heat and Power Technical Assistance Partnership (MA CHP TAP) was established to develop public-private partnerships to advance the technology, policies, and programmatic support for combined heat and power (CHP), including its application in microgrids, heat to power and district energy. The MA CHP TAP’s work includes education and outreach as well as technical assistance to a variety of stakeholders including end-users (commercial, industrial, institutional and more), state decision makers, electric and gas utilities, trade associations and non-profit organizations. This assistance includes evaluating the economic, energy, reliability and environmental value of proposed systems. The MA CHP TAP represents the multi-state Mid- Atlantic region and is the CHP expert in the region who provides fact-based, un-biased information on CHP, including technologies, project development, project financing, local electric and natural gas utility interfaces, and related state best practice policies.

  PublisherDOI

• Energy Dispatch at Controlled Environment Agriculture Sites with Chp: Comparing Optimization and Load-Following Control Frameworks

  SSRN Electronic Journal · 2024-01-01

  preprintOpen accessSenior author
  PublisherDOI

• Energy Dispatch Optimization at Controlled Environment Agriculture Sites with Chp: How Energy Utilization, Storage, and Market Exports Impact Operational Costs

  SSRN Electronic Journal · 2024-01-01

  preprintOpen accessSenior author
  PublisherDOI

• Quantifying the Enhanced Performance of Multifamily Residential Passive House over Conventional Buildings in Terms of Energy Use

  Buildings · 2024-06-20 · 6 citations

  articleOpen accessSenior author

  In response to escalating energy demands and global warming concerns, the Passive House Standard has emerged as a solution in residential construction, aiming to drastically reduce energy consumption and operational costs primarily through high-performance building envelopes. While a considerable volume of the literature has focused on the Passivhaus Institute (PHI) standards, predominantly in European contexts, there is a gap in research on the Passive House Institute US (Phius) standards, particularly in North American climates. This study conducts a quantitative comparative analysis of two adjacent multifamily residential buildings in Central Pennsylvania, Climate Zone 5A—one built using conventional construction methods and the other following Passive House (PHIUS+ 2015) certification standards—to validate the energy efficiency improvements attributed to Passive House designs. A comparative analysis of the whole building energy use over two years reveals that the Passive House building consumes approximately 50% less energy than its conventional counterpart in terms of whole building energy use and the national median recommended benchmark metric defined by the Energy Star Portfolio Manager. These findings emphasize the potential for significant energy savings and greenhouse gas reductions in residential buildings, highlighting the necessity for policymakers and governments to incentivize the adoption of Passive House standards to achieve environmental sustainability and reduce energy costs for society.

  PublisherOA PDFDOI

• Inactivation of HCoV-NL63 and SARS-CoV-2 in aqueous solution by 254 nm UV-C

  Journal of Photochemistry and Photobiology B Biology · 2023-07-05 · 5 citations

  articleCorresponding
  PublisherDOI

• Potential Approach to Comparatively Evaluate Whole-building Energy Use and Indoor Environmental Quality in Passive House and Conventional Buildings

  2023-07-26

  articleSenior author
  PublisherDOI

• Long-term application of low-cost sensors for monitoring indoor air quality and particle dynamics in a commercial building

  Journal of Building Engineering · 2023-09-14 · 20 citations

  article
  PublisherDOI

• Long-Term Air Quality Monitoring in a Commercial Building Toward Healthy and Smart Indoor Environments

  SSRN Electronic Journal · 2023-01-01

  articleOpen access
  PublisherDOI

Frequent coauthors

• William P. Bahnfleth

  33 shared

• Brandolyn H. Thran

  United States Army

  18 shared

• D.J. Seery

  17 shared

• Jae‐Weon Jeong

  Hanyang University

  11 shared

• W.M. Proscia

  11 shared

• Donghyun Rim

  Pennsylvania State University

  10 shared

• Justin Bem

  9 shared

• Steven L. Suib

  University of Connecticut

  7 shared

Labs

• Architectural Engineering LabPI

Awards & honors

• Outstanding Engineering Alumni Award
• ASAE Early Career Impact Award
• Penn State Engineering Alumni Society Awards
• Penn State Alumni Association Awards