Contractors can be stimulated to offer sustainable product innovations through tenders in the GWW sector. But despite the sustainability ambitions of clients to achieve a 100% circular economy by 2050 and sustainably generated energy in the Netherlands, contractors are hindered from being able to offer sustainable product innovations by clients. To make recommendations to clients to optimize the preparation phase of public procurement. In order to contribute to this, it is made clear how contractors can be stimulated by investigating the influential (external) factors of the tender phase that can stimulate contractors to offer sustainable product innovations with a TRL level 7-9 during the tender phase.