Remembering Paul Berdahl, 1945–2026

Paul Berdahl, a retired staff scientist at Lawrence Berkeley National Lab (LBNL), passed away February 5, 2026 in Walnut Creek, California. He was 80 years old. Berdahl spent most of his career at LBNL, including working with the Heat Island Group for 30 years on cool roofing technology to reduce air-conditioning energy use. 

Berdahl was part of the LBNL-led team that won an R&D 100 Award in 2016 for the Cool Roof Time Machine, a protocol to simulate soiling and weathering of roofing materials. The method, approved by ASTM International as an industry standard and adopted by the Cool Roof Rating Council, was designed to accelerate the deployment of energy-efficient cool roof technology. 

Berdahl received his PhD in physics at Stanford in 1972, studying under the eminent theoretical physicist Felix Bloch. He worked at LBNL from 1976 to 2004 and then continued as a rehired retiree until 2015, after which he maintained an active affiliation with the lab. 

Early on, Berdahl coauthored the 1978 California Solar Data Manual and other publications that quantified solar energy resources. He also conducted research on radiative cooling, infrared emission from narrow-bandgap semiconductors, and high-temperature superconductors. Following the deadly Oakland firestorm of 1991, when winds rekindled a grass fire that spread across the East Bay Hills, he explored and patented pigments that reflect fire's radiation. Later in life, he became interested in chlorophyll pigments and the phenomenon of photosynthesis. 

Berdahl’s research on pigments challenged the conventional notion that white was the only paint color effective for cool roofs and buildings. He discovered, for example, that ruby-red pigments can stay just as cool as white by fluorescing, or re-emitting absorbed light. In addition to roofs, the darker color — which was patented in 2023 — was a possibility for cars, ships, and other equipment that sees prolonged periods of sun exposure. Another innovative paper centered on Egyptian blue, a fluorescent pigment that also has potential as a cooling coating. Berdahl’s many publications over a span of more than 40 years were cited thousands of times.