TABLE OF CONTENTS - The Professional Green Building Council

Theme B: Creating a livable, healthy and environmentally viable citiestherefore taking a consumer rather than territorial approach in measuringenvironmental impacts.5.2 Integrating the Ecological Footprint into the Design PhilosophyThe average footprint in rural China currently stands at 1.6 global hectares perperson (gha/capita) and that of an individual living in Shanghai is already around7gha/capita. For a country that is urbanizing rapidly like China it is important tomake effort to reduce the impacts by all new cities. In 2001, Hong Kong'sEcological Footprint was 6.1 gha/capita or 2.2 times the world average [5]. If thesituation remains unchanged, we would need at least 180 times the existing landand sea area we have to support our current lifestyles.Olgyay and Herdt [6] proposed two indicators on measuring ecological footprintfor buildings, namely Index of Building Sustainability (IBS) and Index ofEfficiency in Sustainability (IES). The IBS reflects the fraction of the annualcarrying capacity of the project’s land that is consumed by a building. On the otherhand, IES is the quantity of land required to meet a sustainability goal. These twometrics can be applied to assess both construction and operation impacts. Smallerindices mean less impact to the environment. These indices could be used asindicators to architects and / or building designers to design high performancebuilding with minimal impact.Energy consumption by air-conditioning plays an important part in ecologicalfootprint as it involves the use of fossil fuel. In 2004, approximate 36% of totalenergy was consumed by commercial buildings, from which 28% (equivalent to29,021TJ) was due to air-conditioning [7]. And the study by Panizo [8] stated thatfossil fuel energy consumption accounts for approximate 20% (equivalent to1.25gha/capita) of the total ecological footprint for Hong Kong. It may beconcluded that the ecological footprint for fossil fuel consumed by air-conditioningin commercial buildings is 0.13gha/capita.Through optimizing the design of the Yau Tong Estate Phase 4, the energyconsumption by air-conditioning has been reduced through the utilization ofnatural ventilation and water-cooled air-conditioning system. With a combined211