Space use optimisation and sustainability-environmental comparison of international cases.

As a follow-up to our first paper in this journal, this paper discusses projects involving intensive and multiple use of space recently completed or still being developed around railway stations in London (Broadgate and Canary Wharf), Paris (Seine Rive Gauche and La Défense) and Amsterdam (Zuidas and Bijlmer). The cases were compared on the basis of spatial, functional and environmental indicators, as treated in our first paper. The environmental performance of each of the cases was determined through comparison with a theoretic reference project for an equal number of users, yet with average West-European urban values for spatial, functional and environmental properties. The case studies revealed that a high floor space index is easily achievable in urban plans, implying efficient use of land and preservation of green area outside the city. For a mono-functional office area it is easier to achieve a high FSI than for a functionally diverse area with, e.g. apartments and shops. Therefore, with respect to a reference functionally equal to the cases, the predominant office character of Canary Wharf, Broadgate and La Défense results in good environmental performance. However, on the basis of a functionally diverse reference, for which monofunctional cases were enlarged with additional area for housing and amenities, the varied areas of Zuidas and Seine Rive Gauche perform best. With respect to average urban plans, the cases achieved environmental improvement of factor 1.5. This performance is restricted by the energy consumption of buildings, which has by far the most influence on the end result. The impact of stacking on the use of building materials and energy consumption of buildings is limited, and specific sustainability measures on the building scale were not involved in the calculations. The environmental benefits of intensive and multiple use of space are mainly demonstrated by the great improvement factors for the green area preserved and transport fuel consumption. The environmental costs used for these parameters were however relatively low, leading to a limited influence on the end results. Additional effective improvements to the environmental performance of dense and functionally diverse urban plans are sustainable building design and an integrated approach to urban utilities based on sustainable technologies.