As we wrap up 2024, we are excited to share updates on recent work and also about upcoming events where our research team will share our results with broad audiences from industry and academia. Attendees at CBE Industry Advisory Board meetings may have seen this work in preliminary stages. Much of this work benefits from the invaluable contributions of our industry partners and research affiliates from around the world. For brevity we are reporting only key highlights from among the many recent deliverables and contributors.
Reunion of CBE global community at Comfort at the Extremes 2024 (CATE24)
In November, many current and past members of CBE’s research team participated in CATE24, conference that covers a broad range of topics including comfort, health, climate responsive buildings and resilience. This bi-annual event, this year in Sevilla, Spain, was a great opportunity to reconnect with former students and visiting scholars who have contributed to CBE’s efforts.
CATE 2024 reunion with Toby Cheung, Luís Santos, Veronica Soebarto, Arfa Aijazi, Maíra André, (back row) Federico Tartarini, Tobias Kramer and Charlie Huizenga.
CBE research specialist Charlie Huizenga presented a paper with recommendations from a literature review of indoor thermal conditions and health. The study suggests a maximum safe indoor temperature of 82.4°F (28°C) however the authors note that air temperature alone cannot describe thermal exposure. This work comes from a project that aims to identify maximum safe indoor air temperatures for California homes, and strategies for maintaining indoor temperatures within these limits.
Tobias Kramer, a postdoctoral researcher with CBE, presented a novel metric, spatial thermal autonomy (sTA). The key advantage of sTA is the ability to capture spatial variability in thermal conditions, ‘offering a more comprehensive view of comfort across different building zones.’ The paper also describes how the new metric can be used to use passive design strategies.
Keynote speakers included leaders from CBE’s consortium of industry partners. Christian Schuller, CEO of Sulion, gave a keynote and led a workshop in collaboration with CBE on using fans and air motion to boost sustainability and comfort. Pablo LaRoche, principal of Arcadis and professor at Cal Poly Pomona, provided a keynote on passive cooling, and chaired a session on energy efficient heating and cooling approaches. The next CATE conference takes place in 2026 in Tucson, Arizona.
Diverse and effective strategies to decarbonize HVAC systems in commercial buildings
Over the past several months, CBE’s HVAC research team has released numerous papers and reports, and we outline here three that resulted from a multi-year research program on gas consumption reductions in large commercial buildings, led by Paul Raftery, a professional researcher at CBE.
One paper documents the retrofitting of heating plants and updating HVAC controls to current ASHRAE standards. This work decreased annual natural gas consumption by 70 percent, while also reducing HVAC electricity consumption. The authors note that while we need to electrify HVAC loads to meet climate goals, updating controls first will reduce the size, cost and embodied carbon of heat pump installations. These findings demonstrate an overlooked opportunity for enormous decarbonization in commercial buildings that is cost effective and scalable. ‘We should prioritize these measures first, and then electrify, rather than focusing solely on electrification,’ the authors note.
Another paper analyzed data from hydronic heating systems (heating hot water, or HHW in the US) from over 250 commercial buildings, and found evidence of wasteful design and/or operations. These systems operate far more often than expected — 81% at the median, including many hours when heating would not be expected. Researchers also found that systems are oversized; equipment sized to 30% of the maximum measured load could serve up to 84% of the annual heating needs for the median building. Read more in this LinkedIn post or the full paper. Yet another paper produced under this program, conducted in collaboration with CBE partners Price Industries and Taylor Engineers, was based on extensive laboratory testing of VAV terminal units, and also problems observed in the field. The authors recommend solutions published in an ASHRAE Journal article, and summarized in this LinkedIn post.
We also published reports on a competition design of a grid-responsive multi-family affordable housing prototype, with a team that included David Baker Architects, Taylor Engineers and numerous other contributors, as noted on this project overview. The program required that the building use on-site renewables and energy storage to meet loads during the peak hours of 4 to 9 pm, and to remain in operation during a power outage. Meeting these requirements required creative integration of the envelope, rooftop PVs, battery storage and all building systems. CBE has published the results of the extensive energy simulation results. Also, a comprehensive report on the process and resulting prototype was presented at the 2024 Summer Study on Energy Efficiency in Buildings.
As part of our team’s ongoing outreach efforts, we will be presenting at upcoming industry events and conferences. At the ASHRAE Winter Conference in February, assistant professional researcher Carlos Duarte will demonstrate how thermal mass radiant systems can be used for cost-effective demand management, under a wide range of climatic zones. Berkeley PhD student Aoyu Zou will present work on HVAC marginal operating carbon emissions and load shift potential in office buildings. Also in February, Carlos Duarte and Saeed Danesh, a technical project specialist with the CBE industry partner firm REHAU, will discuss research and trends for cooling with radiant systems, at AHR Orlando. Finally, early in 2025, Prof. Stefano Schiavon will give several talks on heat, health and comfort, including at this event in Singapore.
Promotions, outreach and awards around embodied carbon and LCA program
CBE’s program on embodied carbon and life cycle assessment, one of our newer research areas, is growing and making notable progress. Matt Roberts, who joined CBE as a post-doctoral researcher in 2023 with support from the CarbonWorks Foundation, was promoted in November to the rank of assistant professional researcher. In his new role, Matt will continue expanding the EC/LCA program in order to provide impactful knowledge and resources that can rapidly decarbonize the built environment.
Another acknowledgment is that one of Matt’s recent papers received an Outstanding Contribution Award from the World Sustainable Built Environment Conference 2024. This paper explored soil carbon sequestration (SCS) in building life cycle assessment, using a case study set in a historic grassland that has been depleted due to intensive grazing, and that will focus on restoring the landscape and by doing so increase the SCS rates on site. The work was co-authored by CBE partner Patrick Thibaudeau, and in collaboration with JLG Architects.
Matt and his team, which is growing with the addition of five graduate students from UC Berkeley and other universities, have two other papers in review, including a critical review of LCA of MEP systems. He previously presented the California Carbon Report, in collaboration with the Carbon Leadership Forum. This work is also being shared widely, including at the Net-Zero Conference, at Greenbuild 2024, and in a webinar co-hosted by CBE and PG&E, just to name a few.
This is just an abridged list of our research output since last summer, and we are pleased to share such a broad range of impactful work, and thank our industry partners and research affiliates. We hope you will share this information with your colleagues and others, and we hope to see you at some of these and other events next year.