Sustainability needs more than just smart technology

The performance of the built environment is behind schedule on the way to factor 20 environmental improvement by 2040. A case study with government office buildings, discussed in this paper, stresses the importance of improving more than just building materials and services. Substantial improvement can be achieved by focussing on all three dimensions of sustainability: technological efficiency, efficient use of space and a long functional life span. Space efficiency can be improved by intensive use of space, like innovative work concepts, and multiple use of space, like stacking and combining functions. These avoid claims on rural areas and diminish the amount of building materials and energy needed. The life span of buildings can be prolonged by a sustainable building structure that has possibilities of adaptability to unforeseen future functional changes of the building. Short term contracting in the real estate market requires functional adaptability of office buildings. This functional adaptability is enabled by technical flexibility.