Sustainability should be an important topic in any design brief. As we all know, buildings use a lot of resourcesenergy, water and materialsand they generate a lot of waste, during construction, use and demolition. Clients are in an excellent position to reduce the environmental impact of buildings because they are the starting point of a project. By demanding a green building, they can push the entire supply chain (the design team, the contractor, suppliers) into more sustainable practices. The design brief should explain how far a clients ambitions on sustainability reach. Relevant questions to be answered are: Is the client aiming for a super green building that will set a new standard, or merely seeking compliance with existing sustainability standards? Should the building be merely energy efficient, should it aim to be energy neutral, or should it even produce energy? Is the client open to trying entirely new, innovative sustainability solutions, or should all solutions be proven technologies?It is preferable that clients use measurable and actionable requirements to substantiate their sustainability ambitions. There are several well-established measurement systems that can help with this. A much-used system is breeam (Building Research Establishment Environmental Assessment Method), which clients can use to define the desired sustainability level as Good, Very Good, Excellent or Outstanding. Within the system, these ambitions are connected to concrete requirements on a wide range of issues, including energy and water consumption, health and well-being, pollution, transport, materials, waste and ecology. The disadvantage of systems like breeam is that they require quite a bit of administration on the part of the design team. Furthermore, it has been noted that breeam can trigger box ticking behaviour by the design team: adopting particular solutions just to get the right rating. This is obviously not the intention. Furthermore, it is important to stress that sustainability is not only about certified wood and water-saving toilets, but also about architectural quality, flexibility and usability. There is no point in building a green building, bristling with laudable features, if it does not support the activities of its users. Strategic brief-Formulate general ambitions for sustainability.-Define measurable targets, e.g. based on BREEAM ( or LEED( using multi-interpretable terms such as CO2-neutral or cradle-to-cradle, provideclear definitions.Functional brief-Seek concepts or smart solutions that help to reduce the need for space (i.e. the shared or combined use of spaces and functions).Technical brief-Formulate concrete requirements concerning the use of energy, materials, water consumption.