Not one to shy away from administrative responsibilities, Fanger established the International Centre for Indoor Environment and Energy (ICIEE) at DTU in 1998 and was director of the center until 2004. The facility, funded by a 10-year grant from the Danish government for 10 million euros, had unique environmental chambers that attracted numerous world-class researchers from many disciplines, including classical engineering disciplines, medicine, chemistry, and psychology. The personnel, from some 15 nations, now number more than 50, including 30 graduate students. In 2003, an international evaluation declared ICIEE to be the best facility in the world for studying indoor environment and energy.

Fanger first demonstrated his flair for international activities when he spent a year as a research associate at Kansas State University (1966–1967) at the new Institute of Environmental Research. Under the mentorship of icons Press McNall, Fred Rohles, and Ralph Nevins, he began his investigations of the human effects of thermal comfort. The construction of the environmental chamber at Kansas State was sponsored by the American Society for Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), and Fanger became a member of that organization in 1968. For the next 40 years, he attended most of the biannual meetings, where he could frequently be seen with his many friends and colleagues in the networking lounge.

Fanger spent his second sabbatical year, 2000, at the National University of Singapore (NUS) as Distinguished Visiting Professor. During that year, he initiated collaborative research and development studies between NUS and ICIEE on the impact of indoor environments in different climates on human comfort, health, perceptions, and productivity.

Fanger’s research, which was focused almost exclusively on people’s responses to indoor environments, established the importance of indoor environments to the quality of life. In the 1960s, he introduced indices for quantifying thermal sensation and comfort. The thermal environment can be characterized by temperature (air and radiant surface), humidity, air velocity, and personal parameters (clothing and activity level). Subjective factors obviously influence satisfaction/dissatisfaction with certain