Critical evaluation of zero carbon buildings in high density urban cities

Abstract

Many countries are now developing policies and measures to promote zero or low carbon buildings. However, as a clear definition of zero carbon building (ZCB) and effective evaluation methods for buildings’ carbon footprints are not available, people are often confused about the performance of ZCBs. This research investigates the meaning of ZCBs and develops methods for evaluating their carbon footprints. The definition of ZCB and its related concepts are described. The meaning of footprints and the rationale for using carbon footprints as indicators to measure sustainability are presented. It is found that footprint-based assessment requires a clear understanding of emissions categories, assessment boundaries and carbon accounting principles. The assessment outcome depends on the problem definition and interpretation methodology. The main influences on carbon footprints include building functions, site conditions, energy and carbon intensity of the building systems and components. In order to develop systematic methods for assessing ZCBs, a holistic approach to carbon accounting and footprint calculation is needed. When applying the concepts to assess the buildings in high density cities like Hong Kong, some key factors for urban density and community sustainability should be considered, such as transportation strategy, urban form and typology.