In order to independently verify the commitment of Grand Hotel Huis ter Duin, we work together with two organisations. This makes it immediately clear to an outsider to what extent Grand Hotel Huis ter Duin is committed to sustainability.

The most important partner of Grand Hotel Huis ter Duin in the field of sustainability, is EarthCheck. EarthCheck is the world leader in sustainability certification and is recognised by The World Tourism Organization of the United Nations. Grand Hotel Huis ter Duin received the Silver certification in 2018 and, in August 2025, became the first hotel in the Netherlands to receive the Gold certification. Each year, independent auditors visit the hotel to check this on the basis of the EarthCheck Company Standard. This describes some of the criteria that are checked. Also, an annual EarthCheck document must be made in which the sustainability policy is described.