It was through Frieder Roskam that Siegfried Hoymann first came into contact with the International Work Group for Sports Facility Development in 1968 and has been a member of the IAKS for almost 50 years. In this time he has held various positions at the IAKS. From 2001 to 2015 he was its Secretary General.
Alongside his work for the IAKS, Hoymann has been active on the political stage as a councillor and mayor in the north of Düsseldorf.
Hoymann has always encouraged global contacts in sports facility development, among other things by running numerous IAKS Congresses and conferences.