Acervo Bibliográfico

A number of sustainability indicators can be presented in a form of a theme framework, or they can be aggregated into an index (in some cases referred to as a composite indicator). Mayer (2008) describes an index as a ‘quantitative aggregation of many indicators that can provide a simplified, coherent, multidimensional view of the system’. Selection of SIs for indices requires a balance between simplification and complexity. The indicators should be valid, reliable, comparable and concise and provide the necessary data (Singh et al., 2012).

Many indices have been developed in the last few decades to address various aspects of sustainability. It is argued, however, that many of these indices integrate the same data taken from the existing global sustainability databases. They also use the same methods of data aggregation. The most common aggregation methods are sums, averages, ratios, regression analysis, principal components and others (Mayer, 2008). Singh et al. (2012) categorise the sustainability indices into the following groups:

 Innovation, Knowledge and Technology Indices;

 Development Indices;

 Market- and Economy-based Indices;

 Eco-system-based Indices;

 Composite Sustainability Performance Indices for Industries;

 Investment, Rating and Asset Management Indices;

 Product-based Sustainability Indices;

 Sustainability Indices for Cities;

 Environmental Indices for Policies, Nations and Regions;

 Environment Indices for Industries;

 Energy-based Indices;

 Social and Quality of Life-based Indices.

There are many dozens of various sustainability indices currently used in practice. In this section, a short summary of three widely used indices is provided to demonstrate the use of aggregated indices and examine their benefits and pitfalls. Ecological Footprint Index is widely used in environmental assessment and is easily

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communicated to a wide range of stakeholders. Sustainable Process Index is generally used to evaluate the sustainability of industrial processes. Well-being index is based on socio-economic and environmental indicators and is broadly used for decision-making purposes.

2.6.1. Ecological Footprint Index (EP).

The Ecological Footprint (EF) (Wackernagel and Rees, 1997) ‘quantifies for any given population the mutually exclusive, biotically productive area that must be continuous to provide its resource supplies and to assimilate its wastes’. In other words, EP accounts the land, water and other resource supply chains and disposal management options necessary to sustain a national living standard into infinity. Land and sea are divided into five components: bio-productive land, bio-productive sea, energy land, built land and biodiversity land for non-human species. Footprints are calculated based on either compound or component or combination of these methods. The calculations of the EF are based on the national consumption statistics data. The ratio of required resources to available resources is calculated. If this ratio is more than one, then the living standards are considered to be unsustainable (Böhringer and Jochem, 2007).

There are some useful features of EF index. It takes into account resources consumption, population size and provides information on demand of the human societies on natural ecosystem support. It is a standardised, straightforward, flexible and visual tool that can effortlessly be communicated to the non-experts. However, it is also argued that the EF index is a weak sustainability tool that cannot take into account pollution and significant environmental impacts other than those that can be interpreted as a loss of bioproductive land. In addition it cannot quantify resource depletion that is not translated to a bioproductive area (e.g. minerals) (Gasparatos et al., 2008).

2.6.2. Sustainable Process Index (SPI).

Sustainable Process Index (SPI) is a greatly aggregated index that measures the whole environmental impact of different human activities (Krotscheck and Narodoslawsky, 1996). It was created to evaluate industrial processes and is based on

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mass and energy balances. Extraction of raw materials, energy use, physical installations, air emissions and waste generation are some of the human activities that impact the environment. The SPI has to consider different aspects of these impacts. The total area for sustainable introduction of a specific process into the ecosphere is given by:

Atot = AR + AE + AI + AS + AD, (2.1)

where AR is the area for raw material extraction;

AE - the area for energy provision;

AI - the area attached to physical installations;

AS - the area to support the staff;

AD - the area necessary to disperse all wastes, emissions and products linked

to the process in question of sustainability to the ecosphere.

Services and goods are the products of the processes; therefore the impact per good or service unit is important. It is characterised by

a

= A

/N

,

where NP is the number of goods or services produced by the process.

Ultimately, it is possible to relate the specific area of a certain service or good to the area statistically available to a person to provide all services and goods in a sustainable way, which gives a SPI:

SPI = a

/ a

,

where ain is the area at disposal for each person in a given region (Narodoslawsky

and Krotscheck, 2004).

Any stream leaving a process in the SPI approach is considered to be a product stream, whether it is a valuable product or a waste stream. It is also assumed that all products ultimately dispel into the environment and this forms the basis for calculating the area needed to accommodate products AD. Thus, the SPI estimates the

amount of area required to sustainably embed a process into the environment. This is a different environment tool from LCA (described in section 2.7.1.), which directly

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analyses the waste streams leaving a process and quantitatively assesses the environmental impacts of these streams (Steffens et al., 1999).

It is argued that the major attribute of the SPI assessment is that it makes possible comparing the various impacts of a given technology, therefore it can be used to identify the ecological defects of technologies and can be used to optimise processes in line with their ecological impacts (Narodoslawsky and Krotscheck, 2004).

2.6.3. Well-being Index (WBI).

The Well-being Index (WBI) is an average of the Human Well-being Index (HWI) (an average of 36 standardised, equally weighted socio-economic indicators) and the Ecosystem Well-being Index (EWI) (an average of 51 standardised, equally weighted environmental indicators). The indices HWI and EWI consist of five sub-indices. The HWI includes Health and Population, Welfare, Knowledge, Culture and Society, and Equity Index. The EWI incorporates indices for land, water, air, species, and resource deployment (Böhringer and Jochem, 2007).

There are some pitfalls in using WBI. For example, if a country poorly monitors the sustainability performance in some aspects, it can in fact appear more sustainable due to the lack of data on the unsustainable features. It is also argued that individually the HWI and EWI can provide guidance to policy-makers, yet the WBI is not so easy in this respect (Mayer, 2008).

Although a large number of indices have been developed and used, it is pointed out that some of them fail to meet crucial scientific requirements. For example, there are no general rules for normalisation of the input variables and their weighting procedures, therefore sensitivity analysis should be carried out (Böhringer and Jochem, 2007). It is stated that sensitivity analysis will help to identify methodological biases and increase the transparency of the index to the decision- makers. It will allow identifying the indicators that represent the best option for improvement and those ones that require particular action (Tran et al., 2007).

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