March 6, 2023
Testing Energy Storage Systems (ESS) in Residential Properties
Leveraging both our safety science experience and industry relationships, UL Solutions and the International Association of Fire Fighters (IAFF) initiated a joint project in 2022 under an agreement with the United States Department of Energy (U.S. DOE). This project will focus on two separate and important initiatives related to energy efficiency in residential buildings.
Initiative 1 — Fire Performance on Energy Efficient Exterior Walls
The first initiative of the project addresses concerns surrounding new technologies with enhanced, energy-efficient exterior walls installed on residential properties. The concerns of fire travel extending vertically or laterally were examined. In the United States (U.S.), testing to the exterior wall standard NFPA 285 is required for commercial buildings only, while exterior walls of residential constructions are not typically mandated to undergo fire testing in the same manner. The initiative and its concerns were a natural evolution, stemming from the efforts of Pacific Northwest National Laboratories (PNNL), who had partnered with the DOE in researching existing and innovative retrofitted exterior wall systems. This meant wall systems had to be able to be applied to existing structures that would enhance the insulative performances of these buildings. However, fire performance did not factor into the research.
To initiate the project, the IAFF and UL Solutions team established a Project Advisory Panel and held several virtual meetings to present information on previous fire testing conducted by the UL Solutions Fire Research & Development team and the Fire Safety Research Institute of UL Research Institutes. The panel discussed the development and goals of the earlier PNNL project, and then they developed a test plan.
The test plan incorporated a modified version of an American Society for Testing and Materials (ASTM) test method, ASTM E2707, Standard Test Method for Determining Fire Penetration of Exterior Wall Assemblies Using a Direct Flame Impingement Exposure, as the foundation of the research. The original ASTM E2707 assesses fire penetration into a wall assembly (horizontal burning into the wall, through the layers). This modified method is under development at ASTM and addresses fire propagation (vertical burning up the exterior face of the wall), not fire penetration. The modified method is strictly a draft currently, so using it for this research work served as a suitable proof of some of the concepts. The test method involved a wall structure that is 16’ high by 8’ wide. The sheathing was 1”x6” spruce/pine boards to represent retrofit construction, with no insulation in the stud cavities and an interior 5/8” gypsum wallboard. The objective was to consider various energy-efficient new and retrofitted designs and evaluate how they spread fire vertically or laterally. Through past research initiatives, it was known that fires that extend up the wall and into attic spaces are problematic for first responders. To date, 11 of these tests have been conducted, and results of the full analysis will be in a future report.
Initiative 2 — Firefighting Tactics in Residential Properties with Building Energy Storage Systems
The second aspect of the UL-IAFF Project focuses on the fire service response to Residential Battery Energy Storage System (RBESS) incidents. Again, the IAFF and UL established a Project Advisory Panel with several firefighters who have responded to BESS incidents, representatives from the battery industry, and engineers involved in designing commercial BESS fire and explosion protection solutions.
Through a series of planning meetings, the panel developed a matrix for tests to be conducted within a structure that represents a typical residential two-car garage. The two-car garage was selected after a review of RBESS installation practices identified the garage as the preferred installation location. A review of U.S. Census data identified the attached two-car garage as the most common garage type.
These simulation tests were constructed in the large-scale fire test facility at UL Solutions’ Northbrook, IL campus. A baseline test was conducted that involved a test structure with no batteries—shelving units populated with standardized commodities, representing a typical garage with cellulosic and plastic contents.
Three additional tests have been conducted to generate data with the contribution of energy storage system (ESS) batteries to compare fire and explosion hazards against the baseline test. Through this work, fire service tactical considerations can be explored. To date, from the data, the team can determine 1) the visual indicators of a residential fire that has involved an RBESS (or, potentially, other large batteries), and 2) the impact of fire service-initiated ventilation of the structure on the fire conditions and explosion risks.
Next Steps for UL Solutions, IAFF and DOE
With this milestone of testing complete for Projects 1 and 2, the advisory teams continue to analyze results and determine what next phase of tests will take place. Ultimately, a report of this work will be released to the DOE and made available through IAFF and UL Solutions platforms. We are excited at the opportunity to engage with IAFF and the DOE to use safety science to address these questions related to energy efficiency improvements. To learn more about UL Solutions work in the building and construction space, please visit the UL Solutions Safe, Smart and Sustainable Buildings page.