One way to reduce the environmental impact of the construction sector is the inclusion of environmental requirements in the procurement of construction projects, also called Green Public Procurement (GPP). This thesis first analysed the current inclusion of environmental requirements in the invitation to bid, bid and assessment of the bid. Hereafter, the results were evaluated and a proposal to develop the inclusion of environmental requirements has been made. A misalignment of environmental inclusion was found. Environmental requirements were included in 86% of the 70 invitations to bid, 74% of the bids and 46% of the assessments of the bid. Three defects possibly causing the misalignment were obtained. First of all, ineffective inclusion of environmental requirements in the invitation to bid. Secondly, missing feedback and scores in the assessment of the bid. Thirdly, when feedback was included on the environmental requirements, it was unclear or very limited. As a consequence, environmental requirements are not taken into account in the procurement process. Four purchasing experts from Dutch provinces have been interviewed to evaluate the three limitations and come up with opportunities to resolve them. By looking critically at the expert interview results and comparing them to the results of the content analysis, two problems were noticed. First of all, window dressing: ambitions to improve the inclusion of environmental requirements were stated, but not realised. Secondly, a lack of responsibility. The window dressing and lack of responsibility are caused by the absence of environmental management in the IPM-model. No one is taking action, because no one is responsible. It was concluded that a change in the IPM-model is needed to create responsibility and that the procurement process needs to be improved to incorporate environmental requirements more sufficient. It is recommended to the client to include environmental management in the IPM-model. The environmental management department should have four responsibilities: ensure environmental inclusion, correct limited or incorrect environmental inclusion, learn from mistakes made and develop environmental inclusion based on acquired knowledge. Secondly, a learning process needs to be started. It is recommended to both the client and the contractor to document feedback and review the environmental inclusion in the invitation to bid and bid. The feedback and reviews have to be interpreted and used to improve future invitations to bids and bids. By documenting past performances, future performances can be improved.