A common metrics and set of indicators for assessing buildings and urban fabric sustainability performance

Salat, S.*, Vialan, D., Nowacki, C.

Central Europe towards Sustainable Building, CESB10 Prague, 2010


Many developments have an impact at a larger scale than the single building. A global sustainability assessment method must take into account the urban dimension and not only the single building itself.
The CSTB (The French Centre for Building Science) has developed an original approach through its cross-disciplinary Urban Morphologies Laboratory. For several years now, this collaborative effort of scientists, engineers, architects and urban planners, has been investigating in a dozen world cities the factor of urban morphology and shown that urban morphology alone has an impact on energy performance of the order 2 – i.e. the potential to halve or double a city’s carbon footprint.
The paper will present a common metrics, which links the scales of buildings, urban blocks and neighborhoods for an assessment of energy efficiency of the whole urban fabric including buildings and spaces between buildings such as street canyons. This metrics is based on a set of common comprehensive shape factors: for example the volumetric compactness and solar admittance, which are important for energy efficiency in Central Europe can be evaluated at the 2 scales of building and urban fabric.
The derivation of this metrics into a set of performance indicators is currently developed in the framework of the iiSBE Urban Working group chaired by the author. These indicators will be presented in 12 chapters, which are essential to build sustainable buildings and cities (density, volumetric compactness, connectivity, energy efficiency, bioclimatic potential, etc.) and associated with development strategies.

Keywords: urban morphology, urban metrics, assessment tools, urban sustainability, neighborhood assessment

To measure the performance of a city, its ability to deliver goods and services while offering a pleasant and healthy environment to the citizens and to produce as less carbon emissions as possible, assessment methods have been conceived using different indicators. Indicators are useful tools since they are objective measurements on the contrary to ideals proposed by architects, urban planners or politicians. They enable us to compare cities, to follow evolutions and to observe the results of politics or constructions, and to the consequences of some decisions or plans. A good indicator can be defined by five criteria:

- It must be handful and accessible, which means its analysis must be simple and the data needed to calculate it must be not too hard to access and not too expensive to get.
– It must be relevant, that is to say answering the right question.
– Its results and their explanations must be simple. It must not make the problem even more complex.
– It must be comparable to other indicators and allow comparisons between objects thanks to its results.
– It must improve the global reflection.

Here we present a series of planning more than monitoring indicators, geometrical and related to Urban Morphology. We tried to select a short list, but considering numerous themes and problems of the sustainable city. We classified our indicators following the topics of the human size of the city, its ability to create wealth, the connection and accessibility of the city, its diversity, its density, bioclimatic urbanism, the place of nature and finally the resiliency of the city.