Since the beginning of industrial evolution, industrialization has created a dominating unilateral production- and consumption model. This one-way model of production, also described as a linear model, encompasses a ‘take, make, waste’ pattern in which natural resources are extracted from the Earth, manufactured into goods, used and eventually discarded as waste. It is characterized by a shift in responsibility from the producer of products or goods towards the user in which the consumer has to take care of disposal. Without any incentive to do otherwise, waste will be the final stage of products or goods. The linear economy has proven to be successful in providing affordable products for consumers and material welfare. However, since the publication of ‘limits to growth’ by the Club of Rome during the 70’s, we have witnessed a rising deliberation due to this model’s paradox. The world is finite. The exponential growth in resource extraction due to population growth and shifting consumption patterns in a linear economy is putting stress on our planet. As a result, resource efficiency and depletion will become one of the main challenges during the 21st century. One of the difficulties in developing the circular economy has been related to the topic of procurement. This research focuses on the procurement of circular buildings, specifically on how it should be specified during tender processes. It focuses on the main research question: how can clients (or commissioning companies) of construction projects specify their need/demand order to stimulate circular building? In order to answer this question explorative and unstructured research has been employed on three main themes: circular economy, circular building and tender specification. The circular economy is an economic and industrial system, regenerative by design that aims to maximize the reuse of products and materials and minimizes or eradicates waste by ‘system thinking’. In this research, system thinking is portrayed in form of seven ‘loops’: biochemical feedstock; cascades; maintenance; reuse; remanufacture/refurbish; recycle, which allow materials to flow between the economy and user without becoming waste. Literature study, and interviewees have resulted in three main principles for circular building: 1) using materials that undermine the circular economy; 2) design for circularity; and 3) safeguarding circularity. In order to find out how these principles can be translated to the built environment and how it can be specified during tendering, four case studies have been conducted on construction projects that include circular economy as one of the main concepts. The case studies concluded that the involved parties did their best in attempting circularity but that circular economy in the built environment needs to be further developed in order to fully achieve these principles. The lack of knowledge and measuring tools makes it difficult to specify the circular economy in tender specifications. All four cases had included innovative and new ways of procurement methods. The research concludes the following five steps for clients to stimulate circular building using tender specification: 1) Defining a clear formulation of the client’s ambition; 2) Translating these ambitions to performance-based requirements and possible circular solutions; 3) Determine where to put the emphasis. The more detailed the specification, the more the market parties will be limited; 4) Involving a consortium; 5) Willingness, trust and transparency between the involved parties are key to stimulate innovation and circular solutions.