Nina Holck Sandberg

Exploring built environment stock metabolism and sustainability by systems analysis approaches

The material and energy metabolism of the built environment stocks can be examined by use of a generic model framework that allows for a dynamic analysis where the stocks quantity, composition and quality are related to the demand for service provided to the population. The stock is classified by use of type-age matrices, according to what are the important functions, age structure and material composition of the stock. A mathematical model is demonstrated for calculating the relationship between annual stock size, annual stock change, past inflows and present outflows. This allows for quantification of the material and energy metabolism, in a system life cycle perspective, and its corresponding economic and environmental performance. Various aspects of the approach are applied to selected built environment stocks in Norway, and this paper documents part of this approach for building stocks and road bridge stocks. Le métabolisme des matériaux de construction et de l’énergie des parcs du cadre bâti peut être étudié en utilisant un modèle générique qui autorise une analyse dynamique dans laquelle la quantité, la composition et la qualité du parc sont liées à la demande de fourniture de services à la population. Une classification du parc est opérée en utilisant des matrices basées sur le type et l’âge des bâtiments, selon ce que sont les fonctions importantes, la structure par âge et la composition des matériaux de construction du parc. Il est procédé à la démonstration d’un modèle mathématique permettant de calculer la relation entre la taille annuelle du parc, l’évolution annuelle du parc, les entrées antérieures et les sorties actuelles. Ceci permet la quantification du métabolisme des matériaux de construction et de l’énergie, dans la perspective du cycle de vie d’un système, et de sa performance économique et environnementale correspondante. Les différents aspects de cette approche sont appliqués à des parcs sélectionnés du cadre bâti norvégien, et cet article documente la partie de cette approche qui concerne les parcs de bâtiments et les parcs de ponts routiers. Mots clés: parc bâti, cadre bâti, analyse dynamique, performance du cycle de vie, métabolisme, stocks et flux, indicateurs de durabilité

Dynamic-MFA examination of Chilean housing stock: long-term changes and earthquake damage

The dynamics and metabolism of the built environment are important for understanding the construction, renovation and demolition activities that characterize its long-term physical development. Previous research on building stock development is limited, particularly for developing countries. As one of the most seismically active countries in the world, Chiles built environment is constantly subjected to losses. This study included earthquake vulnerability and damage in a dynamic material flow analysis (MFA) of the Chilean housing stock. Stock and flows of residential floor area were modelled using population and life style parameters. Demolition was modelled assuming a constant demolition rate. By characterizing the building stock according to vulnerability classes and establishing a mass balance per class, the effects of different typology distributions on the overall damage to the stock caused by earthquakes could be assessed. Scenarios with different trends in typology distribution for new construction and renovation suggest that significant potential exists for reducing future earthquake damage in the Chilean housing stock. This is best achieved by gradually reducing the vulnerability of buildings to earthquakes. Legislation, building standards and financial instruments could be used to ensure such reductions in earthquake damage and thereby provide socio-economic benefits in the future.