Sustainability

The Sustainable Building Assessment Tool (SBAT) aims to support the integration of sustainability into buildings and construction processes. Sustainability encompasses both environmental limitations and quality of life and an appropriate definition of sustainability for the built environment has been developed by the World Wildlife Fund (WWF). This describes sustainability as being the achievement of above 0.8 on the Human Development Index (HDI) and the achievement of an Ecological Footprint (EF) below 1.8 global hectares per person (World Wild Life Fund, 2006).

The Human Development Index was developed by the United Nations as an alternative to economic progress indicators and aimed to provide a broader measure that defined human development as a process of enlarging people’s choices and enhancing human capabilities (United Nations Development Programme, 2007). The measure is based on:  

• A long healthy life, measured by life expectancy at birth
• Knowledge, measured by the adult literacy rate and combined primary, secondary, and tertiary gross enrollment ratio
• A decent standard of living, as measure by the GDP per capita in purchasing power parity (PPP) in terms of US dollars

An Ecological Footprint is an estimate of the amount of biologically productive land and sea required to provide the resources a human population consumes and absorb the corresponding waste. These estimates are based on the consumption of resources and production of waste and emissions in the following areas:

• Food, measured in type and amount of food consumed
• Shelter, measured in size, utilization and energy consumption
• Mobility, measured in the type of transport used and distances travelled
• Goods, measured in type and quantity consumed
• Services, measured in type and quantity consumed
• Waste, measured in type and quantity produced

The area of biologically productive land and sea for each of these areas is calculated in global hectares (gha) and then added together to provide an overall ecological footprint. This measure is particularly useful as it enables the impact of infrastructure and lifestyles to be measured in relation to the earth’s carrying capacity of 1.8 global hectares (gha) per person.

The World Wildlife Fund combined the Human Development Index and Ecological Footprint in a graph as shown below (World Wild Life Fund, 2006). This indicates that countries in Europe and North America have very high Ecological Footprints and acceptable Human Development Indexes (above 0.8), while countries in Africa have unacceptably low Human Development Indexes (below 0.8) but have Ecological Footprints within the biosphere’s allowable capacity per person.

The graph also indicates national development trajectories (the lines between the diamonds and dots). For example, the trajectory of the USA has been steep, with a large increase in their ecological footprint and relatively limited improvement in their Human Development Index in the last 20 years. In contrast, Hungary, over the same time period, has improved its Human Development Index to achieve the minimum sustainability criteria and, at the same time, reduced its ecological footprint.

This suggests that strategies based on an understanding of current HDI and EF performance can support a shift towards sustainability (Moran et al, 2008). This is supported by Holden and Linnerud, who argue through reference to purchasing price parity and ecological footprint measures, that developing and developed countries require different strategies to achieve sustainability (Holden &Linnerud, 2007)

There is, therefore, a strong argument that built environment development strategies should respond to local EF and HDI performance and, through the appropriate provision, support sustainable development trajectories. The Sustainable Building Assessment Tool aims to support this goal.