Claes-Goran Granqvist is Senior Professor of Solid State Physics at the Ångstrom Laboratory, Uppsala University, Sweden, and has held his position since 1993. During 1989–1993, he was Professor of Experimental Physics at Gothenburg University, Sweden. Much of Granqvist’s research is concerned with materials—especially functional thin films—for energy efficiency and solar energy utilization in the built environment. Electrochromics-based and thermochromics-based “smart windows” are two examples. Granqvist has published more than 550 scientific articles and about 30 books and conference proceedings. He has given more than 250 invited talks, mainly on energy related issues, and he has organized about 40 international conferences. Granqvist is a member of the Royal Swedish Academy of Sciences and the Royal Swedish Academy of Engineering Sciences. He has received several prizes and awards, most recently the 2015 Jan Czochralski Award. Granqvist is one of the founders of ChromoGenics AB, a company with some 20 employees, for producing electrochromic foils devised for glass lamination.