The construction sector in Denmark has in January 2023 been subjected to new climate demands, that requires life cycle assessments (LCA) on all new construction projects. They also must comply with a new threshold value for all buildings of more than 1.000 m2 for CO2-emissions. This paper inves-tigates the effects of these demands on the Danish contractors, their work and on their cooperation with other actors in the organizational and institu-tional field. A single case study is structured in which six separate interviews are performed with employees of contractors and experts to gather empirical evidence. An analysis is performed of their rationale and underlying institutional logics in dealing with the climate requirements. It includes and examination of which institutional logics are prevalent for the entrepreneurs in their work with environmental sustainability and how it affects their response to the demands and thus the institu-tional work they perform to create, change, main-tain and break down institutional field level struc-tures. The study shows the expected effects of the climate requirements on cooperation between ac-tors in the construction industry, areas of responsi-bility in relation to sustainable construction, envi-ronmental data processing and an analysis of the approaches to climate sustainability that are seen as legitimate in the industry.