Evaluation of policies to enhance environmental sustainability in small to medium sized Irish settlements

There is a strong political desire for methods to assess the impact of policy implementation on overall sustainability targets, but this has proved in the past to be very challenging, as views on the meaning of sustainability vary, and methods developed which satisfy scientists’ needs for rigour are deemed too complex and inadequately transparent by decision-makers. Until recently, there was a shortage of relevant quantitative data on which to base assessment of policies. However, it is vital that we are able to measure sustainability in order to check whether a new policy, decision or technical innovation is helpful in enhancing sustainability. In relation to government action and put simply, what gets measured gets done: if it cannot be measured it cannot be managed. This thesis reports on a method for the evaluation of policies to enhance urban sustainability, using a metric which is designed to be both scientifically robust and policy-relevant in that it is both quantitative and readily usable by decision makers. Approximately 75% of greenhouse gas emissions (GHG) are associated with lifestyle choices, with transport and household based consumption being responsible for the largest shares, concentrated in urban areas. This consumption is important in national and local scale policy development for reducing GHG emissions. It has been difficult to prioritise urban sustainability policy roll out as it has not been possible to estimate overall sustainability enhancement resulting from implementation of candidate policies. This research describes a new method and metric designed to enable a quantified estimate of benefits associated with urban sustainability policy implementation. Existing approaches to sustainability measurement have focused on ranking settlements in terms of sustainability. These approaches can be used to compare sustainability of a settlement over different time periods or to compare sustainability between different settlements but have largely not been designed to model potential sustainability policy impact at settlement level. There are a number of existing methods and models for the evaluation of sustainability policy such as Environmental Impact Assessment (EIA), Strategic Environmental Assessment (SEA) and Sustainability Impact Assessment (SIA). These methods and models are either project based in the case of EIA, or in the case of SEA and SIA evaluate policy impacts in a generalised manner. There is need for an approach to evaluate policy impact on settlement sustainability in a standardised quantitative manner. Like the many facets of the concept of sustainability itself, proper metric development can only happen when significant parameters, specific and general, are considered simultaneously. Many metrics seeking to model sustainability approach it from one particular area of expertise: however, one index is inappropriate for fully understanding the sustainability of a system, and therefore several indices used in combination are required. The Quantitative Evaluation of Settlement Sustainability Policy (QESSP) approach described in this research seeks to address these gaps in our knowledge by developing a method and metric based in multiple indices, with the ability to evaluate sustainability policies and provide an evidence base for policy making. The method developed seeks to avoid reductionism by including 40 quantitative sustainability indicators, so as to allow for detection of possible cumulative impacts, and rebound effects. It is recognised that many factors influence our ability to implement policies: included in the overall method is a novel approach to feasibility testing. The research also advances our understanding of the level of sustainability achieved by Irish settlements, and points to lessons for more sustainable spatial planning.