Benefits of green infrastructure 1 Benefits of green infrastructure 2 Contributors Benefits of green infrastructure Benefits of green infrastructure Report to Defra and CLG October 2010 Prepared by Land Regeneration and Urban Greenspace, Centre for Forestry and Climate Change, Forest Research, Farnham, Surrey The report should be cited as: Forest Research (2010). Benefits of green infrastructure. Report to Defra and CLG. Forest Research, Farnham. Steering group Authors Sarah Andrews - Defra Executive Summary Ian Barrett – Defra Andy Moffat Bruce Collinson – Homes and Communities Agency Kathryn Deeney – Natural England Introduction and Conclusions Carl Foster – Forest Research Andy Moffat Tony Hutchings Andrew Gale – Natural England Carl Foster Helen Gibson – CLG Deborah Holmwood – The Land Trust Economic benefits Tony Hutchings – Forest Research Vadims Sarajevs Gregory Valatin Eleanor Lucas – Environment Agency Glenn Millar – British Waterways Social benefits Peter Neal – CABE Space Amy Stewart Gareth Price – Forestry Commission Anna Lawrence Star Molteno John Robbins – Defra Environmental benefits Editing Gail Atkinson Jenny Claridge Andy Brunt Ros Bryant Carl Foster Kieron Doick Tony Hutchings Vicki Lawrence Land regeneration benefits Gail Atkinson Ros Bryant Kieron Doick Vadims Sarajevs Gregory Valatin Hydrological benefits Nadeem Shah Samantha Broadmeadow Ecological benefits Amy Eycott 3 Benefits of green infrastructure Contents Executive summary ........................................................................................... 6 1. Introduction .................................................................................................. 9 1.1 What is green infrastructure? ........................................................................9 2. Economic benefits ....................................................................................... 14 2.1 Introduction ..............................................................................................14 2.2 Critical review ...........................................................................................14 2.2.1 Economic growth and investment ..............................................................14 2.2.2 Land and property values, and aesthetics ...................................................19 2.2.3 Economic toolkit .....................................................................................25 Appendix 1 Methodology ..................................................................................26 Appendix 2 Terminology...................................................................................28 References .....................................................................................................32 3. Social benefits ............................................................................................. 35 3.1 Introduction ..............................................................................................35 3.2 Critical review ...........................................................................................36 3.2.1 Improving levels of physical activity and health ...........................................36 3.2.2 Promoting psychological health and mental well-being..................................43 3.2.3 Facilitation of social interaction, inclusion and community cohesion ................49 3.2.4 Valuation toolkits ....................................................................................55 3.2.5 Practical considerations – barriers to green space use ..................................57 References .....................................................................................................61 4. Environmental benefits................................................................................ 70 4.1 Introduction ..............................................................................................70 4.2 Critical review ...........................................................................................70 4.2.1 Improving air quality using green infrastructure ..........................................70 4.2.2 Green infrastructure and sustainable drainage systems ................................79 4.2.3 Green infrastructure and the urban heat island............................................85 4.2.4 Environmental and aesthetic quality...........................................................93 Appendix 3................................................................................................... 105 References ................................................................................................... 106 5. Land regeneration ..................................................................................... 115 5.1 Introduction ............................................................................................ 115 5.2 Critical review ......................................................................................... 116 5.2.1 Regeneration of previously developed land ............................................... 116 5.2.2 Quality of place, a sense of place ............................................................ 128 5.2.3 Regional and local economic regeneration................................................. 139 4 Benefits of green infrastructure References ................................................................................................... 147 6. Hydrological benefits................................................................................. 153 6.1 Introduction ............................................................................................ 153 6.2 Critical review ......................................................................................... 155 6.2.1 Impact of urbanisation on the hydrological cycle........................................ 155 6.2.2 Hydrological benefits of GI: flood alleviation.............................................. 155 6.2.3 Hydrological benefits of GI: water quality ................................................. 160 6.2.4 Valuation: toolkits and unit cost of benefits/economic valuation data............ 162 References ................................................................................................... 165 7. Ecological benefits..................................................................................... 170 7.1 Introduction ............................................................................................ 170 7.2 Critical review ......................................................................................... 171 7.2.1 Benefits and potential costs of urban GI for biodiversity.............................. 171 7.2.2 Biodiversity strategies and policies .......................................................... 179 7.2.3 Valuation: toolkits and unit cost of benefits/economic valuation data............ 184 References ................................................................................................... 186 8. Knowledge gaps and suggestions.............................................................. 191 9. Conclusions ............................................................................................... 195 5 Benefits of GI Benefits of green infrastructure Executive summary The content of this report Urban policy today can be classified as hitting three main targets: • economic development, including local economic activity, income generation and employment policy; • social development, including housing and neighbourhood issues, relations within and between communities, and social inclusion; • environmental issues, concerned with spatial relationships in the city, planning, transport and the urban infrastructure. From the perspective of green infrastructure, the report examines how these main policy objectives can be supported. It provides a synthesis of the evidence on the benefits of green infrastructure, based on expert evaluation of scientific and other related literature. Each of the main chapters is structured in a similar way: after the introduction, the main part is devoted to the critical review of the evidence, followed by the identification of potentially useful toolkits, knowledge gaps, case studies and a list of key bibliographic references. The following gives a short summary of each of these chapters. Economic benefits Placing accurate economic values on green infrastructure or its green space components is far from easy, but is vital to support the case for sustained investment. Although the vast majority of the evidence points to green infrastructure benefiting many vital aspects of social and environmental sustainability, the challenge is in convincing budget holders of the economic value of such ‘indirect’ impacts. In most cases there is little doubt that returns on green infrastructure investment are high, but without adequate demonstration it is often difficult for investments to be made in line with other initiatives where direct cost-benefit valuation is simpler. A series of case studies where economic valuation has taken place are discussed in order to demonstrate the net economic value of initiatives to create or improve green infrastructure. There is good evidence that green space can make positive impacts on both local and regional economic regeneration, especially for job creation, business start up and inward investment. However, the quality and quantity of this evidence is comparatively poor and further research is needed