Urban forms and resource productivity
Factor 10: Multiplying by 10 Resource Productivity in the Urban World
Salat, S. & Bourdic, L.*
Proceedings of the World Sustainable Building Conference SB11 Helsinki, Finland.
The next doubling of the global urban population and the double constraint on planetary global resources and climate change will involve doubling the available wealth while dividing by five the consumption of resources needed to produce it. This is an extremely ambitious goal. Following the approach of Ernst U. von Weizsäcker, the paper will develop a factorial approach to increasing urban resource productivity combining cumulative multiplicative factors such as the productivity of urban form, systems efficiency and people behaviour. The design of cities constitutes the greatest potential source of savings at zero or negative cost. The paper will present an innovative approach that highlights the multiplicative effects of multi-scale urban policies. It provides a new theoretical framework to analyse both for transport and building energy consumption. It aims at being used as a steering tool for urban energy policies, by allowing a comparison of investments at different scales: city scale, neighbourhood scale, systems and individual behaviours.
Based on an algebraic factorising, this method splits energy consumption into 4 elements, everyone corresponding to a specific scale. One of the main interests of this method is that it can be used for every urban energy sector: heating, cooling, lighting, but also transportation. This factoring method leads to an urban energy efficiency formula that highlights the influence of every scale on energy efficiency. The further advantage of this approach is that it can be used to scrutinize the effect of a marginal change in one of the parameters on the overall urban efficiency. The novelty of this approach is that it actually uncouples efficiency levers that used to be mixed up and inseparable before. It could furthermore be used in policy-making as a financial tool to compare the impacts, the costs and the relevance of energy efficiency measures at different scales. Following this factorial approach, the productivity of the urban system can be multiplied by ten through a combined action on urban morphology, connectedness and spatial distribution, on bioclimatic architecture, on synergy grids for closing all material and energy loops and on significant changes in people behaviour.