In recent years, the emergence of the cloud computing has increased the need of resources to support cloud-based services. Therefore, the role of the data centers has become essential. Following the growing of services, the power consumption has increased dramatically, while the need for energy savings and CO2 reduction has become a requirement for a sustainable world. The All4Green project fosters collaboration between energy providers (EP), data centers (DC) and customers/end users (EU) in order to provide energy sav-ings and CO2 emissions reduction. In this architecture, the contract binding EPs and DCs includes flexibility terms in order to allow the collaboration in the form of discounts that can be transferred also to DC customers, if they are willing to collaborate.