Ulens started his career at Glaverbel at the new products division in 1969. He continues his career in marketing, sales, export of special glass and later on all flat glass for the building industry. In 1981, Glaverbel was acquired by the Asahi Glass Company (AGC) of Japan. In 1989, he was appointed Directort of Glaverbel Canada. Ulens returned to Europe in 1995, joined the board of directors of the Glaverbel Group and managed the Architectural Glass unit. In 1998, he was appointed director of the Building division and in 2002, he became CEO and President of the board of directors of the Glaverbel Group. In 2005, he was appointed head of AGC Flat Glass. He retired on 1 April 2008.
