Already during her studies at the Conservatory of Rotterdam, Iris Giel attended performances of Dutch National Opera whenever the company was in Rotterdam. During her education, DNO asked the conservatory for vocalists to participate in the opera Satyagraha by Philip Glass. This was her first acquaintance as a soprano with DNO, as well as the first opera in which she ever sang. This also granted her a place in the freelance chorus, which eventually resulted in a permanent position, even before Iris had finished her studies.
During the 36 years that Iris has worked for the chorus, she has also sung many solo roles in oratorios, opera, operetta and song concerts, as well as at the Lunch Concerts of Dutch National Opera & Ballet.