Harmen is chairman of the Jazz Piano Faculty at the Conservatorium van Amsterdam / University of the Arts Amsterdam, internationally recognized as one of the leading jazz programs worldwide. He teaches the principal subject of Piano Jazz, ensembles, coaches student groups, and Master electives.
Harmen is frequently invited to give workshops and masterclasses throughout Europe and beyond. He has been a guest at institutions including the Royal Conservatory of Brussels (BE), Royal Conservatoire Antwerp (BE), KASK & Conservatorium / School of Arts Gent (BE), Norwegian Academy of Music Oslo (NO), LUCA School of Arts – Lemmensinstituut Leuven (BE), Codarts University of the Arts Rotterdam (NL), Royal Conservatoire The Hague (NL), HKU Utrechts Conservatorium (NL), Fontys Academy of the Arts Tilburg (NL), Conservatorium Maastricht (NL), ArtEZ Conservatory Zwolle (NL), Manhattan School of Music New York (US) – for an online masterclass, Grieg Academy – University of Bergen (NO), Conservatoire National Supérieur de Musique et de Danse de Paris (FR), and Zurich University of the Arts (ZHdK) (CH).
He has also been invited several times as a faculty member of leading international jazz summer programs, including the Siena Jazz International Summer Workshop (IT) and the Conservatorium van Amsterdam Summer Jazz Workshop (NL), bringing together renowned artists and talented young musicians from around the world.
Harmen has served several times as a jury member for the finals of the Keep an Eye International Jazz Award, a competition bringing together outstanding young vocalists and instrumentalists from leading conservatories in Europe and the United States. Besides his role as a jury member, he has coached international ensembles from institutions including the Sibelius Academy Helsinki (FI), Boyer College of Music and Dance – Temple University Philadelphia (US), The Juilliard School New York (US), Conservatoire National Supérieur de Musique et de Danse de Paris (FR), Siena Jazz University (IT), USC Thornton School of Music (US), and the Conservatorium van Amsterdam (NL).