TABLE OF CONTENTS - The Professional Green Building Council

Theme B: Creating a livable, healthy and environmentally viable cities2. MACROLEVEL FLUX ANALYSIS: METABOLISMCOMPARISON BETWEEN ASIAN AND EUROPEAN CITIES2.1 Cities MetabolismAn urban metabolism analysis [1] is a means of quantifying the overall fluxes ofenergy, water, material, and wastes into and out of an urban region. Analysis ofurban metabolism can provide important information about energy efficiency,material cycling, waste management, and infrastructure in urban systems. Thematerial metabolism of the modern city is based on the redeployment of theprocesses of nature. This redeployment provides energy for processes in whichcomplex social and physical hybrids (heating, lighting, transportation,communication, water-supply systems and climate-controlled micro-environments)are built from simpler structures.2.2 Linear Metabolism versus Circular MetabolismFollowing the economic growth euphoria of the post-war years, increasinglyprofligate use of resources became the norm in the second half of the 20th century.Cities acquired an essentially linear metabolism, with little concern about theorigin of resources flowing into them and the destiny of waste emanating fromthem. This has become a major systemic problem regarding their environmentalsustainability. To become sustainable, cities must be more closed-loop ecologicalsystems. Cities should thus be apprehended in their entirety as ecological systems.They should be as autonomous as possible by optimising resources reuse, withinput and output levels (resources and wastes) that respect the carrying capacity ofthe earth.2.3 The Planetary Metabolism of Global CitiesModern cities depend heavily on materials and energy from outside theirboundaries. London total ecological footprint is 300 times London surface area.London’s per capita ecological footprint, at 6.6 ha, is lower than that of New Yorkor Los Angeles, at more than 10ha, but in a world of cities, where American,Australian and European lifestyles are copied all over the world, significantimprovements in resource productivity are called for.413