Validating Thermal Performance of Existing Assemblies Using In-Situ Measurements

For architects, engineers, and building owners, the thermal performance of existing or historic building envelopes is often difficult to determine with a high level of accuracy. To obtain greater baseline performance accuracy for energy models, especially for deep energy retrofit projects, in-field measurement tools can be used to obtain real-time data on the conductivity of the existing assemblies. This presentation will focus on the typical procedures of in-situ U-factor measurement, outline the capabilities and limitations of the tool set, and recommend ways to improve the validity of measurements using case studies. For older buildings, the records of existing assemblies are often incomplete or inaccurate. The in-situ U-factor measurement tool set is especially useful for architects and engineers when the status of the existing materials is unclear. For a documented assembly, these field measurements assist in validating the U-factor estimates. If the field-measured U-factor consistently varies from the calculated prediction, those measurements prompt further study. For an undocumented envelope, field measurement is an excellent nondisruptive method for building owners and their consultants to estimate the thermal performance of an existing envelope. Every measurement is different due to key factors such as weather conditions, interior boundary, thermal mass, etc.

Learning Objectives
At the end of this session, the attendee will be able to:

• Explain the benefits of utilizing in-situ measurements during an existing building restoration or deep energy retrofit project.
• Summarize the key steps of implementing sensors to measure assembly conductivity in the field.
• Describe heat flux patterns of various measurement conditions in typical wall and roof assemblies.
• Utilize strategies described in the session to improve the accuracy of thermal evaluation for existing assemblies.

Presenter/Author

Shibei Huang, NFRC Certified Simulator

Building Enclosure Consultant, RWDI

A highly motivated building enclosure consultant with RWDI's Philadelphia team, Shibei Huang possesses technical skills specific to high-performance buildings, energy code compliance, assembly performance analysis, and construction administration. With a background in architecture design, Huang has extensive experience in institutional projects and across all project phases. Her analytical skills and knowledge of building science and historic preservation contribute to a deeper understanding of building performance and help inform building designs. She holds a BArch from the University of Oregon and an MSD in environmental building design from the University of Pennsylvania.

Length: 00:43:37

Last Updated: April 28, 2025