Sustainability is advancing rapidly through different industries and consumers are increasingly aware of its importance. In software industry manufacturing (developing) and logistics (distribution) are not the main concerns. Most of the emissions in software come from the use of the services. On the other hand, consumers are not necessarily thinking their smart phone apps or computer software has any impact on the climate change or reaching the net-zero goals. Currently the studies show that ICT sector contributes to 3,9 % of the global greenhouse gases, but it is projected to rise to 14 % by 2040. The regulations regarding sustainability of software will keep on getting stricter towards the future, so the right time to prepare is now. A three-party model has been identified as a potential approach, where software buyers would be able to define the sustainability metrics, software providers to certify their sustainability concretely and developers to keep up with the metrics. How should such system work in practice? What are the factors that are meaningful in the process and how would products and certificates look and feel like to have an impact. Join the project to create concrete demos of greener, certified software model!