A quantitative method for the evaluation of policies to enhance urban sustainability

Abstract

There is a need to define sustainable development in terms which are more clearly policy-relevant, so as to facilitate the quantitative evaluation of sustainability policies. This paper presents a novel quantitative method to evaluate urban sustainability enhancing policies to further enable evidence based policy making. Quantitative data on more than 300 economic, social and environmental attributes of 79 small to medium sized urban Irish settlements were assembled into a database. This provided a baseline against which projected impacts of fresh policy implementation may be evaluated. Literature searches for assessments of the impacts of policy implementation provided quantitative data on the likely impacts of policies in transport, environment, socio-economics and quality of life. The method has been named Sustainability Evaluation Metric for Policy Recommendation (SEMPRe), and is designed to be user-friendly for decision makers. SEMPRe assigns each candidate policy a numeric value indicating its projected effectiveness in enhancing settlement sustainability as an aid to evidence based decision making. As further quantitative assessment of impacts of additional policies are published in future, the range of policies testable using SEMPRe will increase.

Introduction

There is a strong political desire for the comprehensive assessment of changes in economic, environmental, and social conditions, but this has proved difficult because of competing characterisations of sustainability and a lack of hard evidence (Böhringer and Jochem, 2007). It is vital that we are able to measure sustainability in order to check whether a new policy, decision or technical innovation is making things better or worse (Darton, 2003). Put simply, if it cannot be measured it cannot be managed effectively. Here, settlements are defined as individual towns and villages with an urban area comprising single or multiple electoral districts as identified within the 2006 National Census (CSO, 2007).

Principles of sustainable development have been suggested to provide guidance for its implementation, but sustainability remains a contested and value-laden concept (Harding, 2006), and proponents of the varying characterisations of sustainability rarely find grounds for agreement (Kallio et al., 2007). These debates are not reviewed here. Further, previous sustainability metrics are not easily used to evaluate the likely success of competing policies, which is needed if we are to strengthen evidence based decision making. The aim of this paper is to describe a method developed specifically to assess quantitatively the likely impact of the implementation of policies designed to enhance sustainability of urban areas. The method is called Sustainability Evaluation Metric for Policy Recommendation (SEMPRe): in this section the key issues behind its development are discussed briefly. In developing the method, assumptions were made. The first is that urban settlements will continue to exist within a more sustainable future. The second is that emissions of greenhouse gases leading to climate change, represents the most important current environmental challenge. The third is that, pragmatically, settlements require a continuous inward flow of income to maintain infrastructure, cultural assets and services. Fourth, settlements survive only as long as people chose to live in them, so that maintaining a strong socio-economic base and quality of life are as important as local environmental issues. In designing SEMPRe, three concepts were considered to be crucial. Vulnerability refers to the degree to which a coupled human/environment system or some part of it is likely to experience harm due to exposure to a hazard (Turner et al., 2003). Resilience refers to the amount of disturbance such a system can absorb and still remain within the same state or domain of attraction (Folke et al., 2002). Ecosystem services are the benefits people obtain from healthy ecosystem functioning (MEA, 2005). The term describes a framework of structuring and synthesising our understanding of ecosystem processes in terms of human well-being (Brauman et al., 2007). Thus, sustainable development of a settlement entails minimising vulnerability, maximising resilience and maintaining or enhancing ecosystem functions.

As the impacts of previous and current developments threaten the provisioning of society and the maintenance of life support systems, decision makers want to know about these threats and their implications, including the capacity (or adaptive capacity) of the system, foremost the human subsystem, to withstand and adjust to them (Turner, 2010). The importance of measurement to quantify change and improvement has long been recognised and over the last few decades, it has become increasingly important at national scale to be able to quantify and measure sustainability in order to meet legally binding targets. Agenda 21 stated that commonly used indicators, such as the gross national product (GNP) and measurements of individual resource or pollution flows, do not provide adequate indications of sustainability. A standardised set of indicators of sustainable development need to be developed to provide solid bases for decision making at all levels and to contribute to self-regulating sustainability of integrated environment and development systems (UN, 1992). At a global scale there are over 500 published sustainability indicator studies (Parris and Kates, 2003, Böhringer and Jochem, 2007), and Mori and Christodoulou (in press) review twelve well known indicators especially relevant to urban areas. The search for better sustainability indicators is not only a technical problem, it is also concerns what we value (Levett, 1998). The public good nature of many environmental goods and services, and the difficulties in objectively estimating indirect, cumulative and long-term costs and benefits, create problems in defining environmental performance (Srebotnjak, 2007). There is a high degree of uncertainty in the design and use of sustainable development indicators. Which sustainable development indicators are selected or rejected and by whom, what system of weighting is adopted, and how they are measured and presented, are all factors that influence the quality and scope of information we gain (Wilson et al., 2007).

Previous approaches to sustainability measurement have focused on ranking entities such as states and settlements in terms of their sustainability. These approaches can be used to compare sustainability of a settlement or region over different times or to compare sustainability between different settlements or regions. However, they were not designed to evaluate sustainability policy outcomes.

There are a number of existing methods for the evaluation of sustainability policy such as Environmental Impact Assessment (EIA), Strategic Environmental Assessment (SEA) and Sustainability Impact Assessment (SIA). These methods are either project based (EIA) or evaluate broad policy impacts (SEA and SIA) without reference to single settlement scale. Because of the many faceted concept of sustainability, proper tool development can only happen when all major parameters are considered simultaneously (Ness et al., 2007). Many indices seeking to model sustainability are single discipline based. However, one index is inappropriate for fully understanding the sustainability of a system, and therefore several indices used in combination are required (Mayer, 2008). SEMPRe seeks to address these issues by adopting a method based in multiple indicators, with the ability to evaluate sustainability policies and inform policy decisions made at settlement specific but also if required at regional and national scales. It seeks to avoid reductionism (Bond and Morrison-Saunders, 2011) by inclusion of 40 settlement sustainability indicators representing environmental, socio-economic and environmental pillars of sustainability, but not individually and rather as representing aspects of the urban system as advocated by Bell and Morse (2008).

A literature search identified important arenas in policy making for enhancing settlement sustainability: these are transport, food, housing and urban form, energy, waste, and water. For each arena, literature searches identified studies in which the effects of policy implementation were evaluated quantitatively. The number of such studies has increased significantly in recent years, and hopefully this trend will accelerate in future.

The objectives of this paper are:

• to describe the development of SEMPRe,

• to explain the selection of indicators included in SEMPRe,

• to explain the selection of sustainability enhancing policies for evaluation,

• to present some preliminary results of evaluation, and

• to review strengths and weaknesses of the current SEMPRe method.