Permitted development rights to support the provision of new homes: SEA Environmental Report

5. Secondary, cumulative and synergistic effects

5.1. Introduction

5.1.1 This section considers possible secondary, cumulative and synergistic effects between all of the developments for which options for PDR changes have been assessed. It is not currently known which potential PDR will be progressed or the extent to which PDR will change. This section therefore summarises the maximum potential secondary, cumulative and synergistic effects.

5.2. Assessment of effects

Air

5.2.1 Minor negative impacts on noise and air quality, including from dust and odour, may arise during construction across all the development types. These effects will however be temporary and localised and can be managed at project level.

Biodiversity, flora and fauna

5.2.2 Options for PDR together may result in significant negative cumulative effects on biodiversity, flora and fauna. Key potential contributors include the conversion of agricultural and forestry buildings, the replacement of buildings with new-build dwellings and new-build homes, with the potential for habitat loss and fragmentation at local level, as well as impacts to local wildlife. PDR also removes the opportunity to consider biodiversity and biodiversity enhancements through the planning application process.

Climatic Factors

5.2.3 Several options for PDR may act together to support policies which aim to reduce greenhouse gas emissions. This includes PDR that facilitate the conversion and reuse of existing buildings and expanded PDR for low/zero carbon heating and cooling technologies.

5.2.4 There are also a number of options that have the potential to lead to increased emissions. For example, several options for the provision of new homes could increase reliance on private vehicles and could facilitate the loss of embodied carbon through the replacement of existing buildings. PDR for town centre living could change travel patterns depending on whether trade moves to out of town locations or is displaced by on-line retailing. Overall, there is the potential for mixed cumulative effects for climate depending on which options are taken up.

Cultural Heritage

5.2.5 Several PDR options have potential for significant negative effects on cultural heritage. For example, householder development, changes of use in town centres, and new-build homes could impact the setting of conservation areas and undesignated historic townscapes, and incremental changes may take place over time.

5.2.6 PDR for development which facilitates groundworks can lead to significant negative impacts on belowground undesignated archaeology and historic battlefields.

5.2.7 Any potential expansion of PDR also removes the opportunity to consider design and meet ambitions around improving the quality of the built environment through the planning application process.

Landscape and geodiversity

5.2.8 A number of options have potential to result in a significant cumulative negative effect on landscape and geodiversity, particularly where PDR facilitates development located on the edge of settlements or in the open countryside. Key potential contributors include new build homes in rural areas and certain householder developments. Negative effects could be mitigated by restricting PDR.

Material Assets

5.2.9 With the exclusion of options to introduce PDR for new homes in rural areas, a number of options have potential for cumulative positive effects on material assets associated with the uptake of low/zero carbon technology and retention of existing buildings

Water

5.2.10 A number of PDR options relate to development that could increase flood risk, leading to significant cumulative negative effects on flooding. Small incremental increases in impermeable surfaces can act together to increase the speed and volume of surface water runoff. Flooding can have impacts on other infrastructure, for example sewage treatment works, and pollution associated with flooding can have negative effects on environmental health and biodiversity. These effects may be partially mitigated through restrictions on PDR.

5.2.11 In areas where drinking water is supplied from boreholes and/or abstracted from other sources, options for PDR which support new housing can put pressure on this resource with potential for cumulative negative effects.

Other

5.2.12 Introducing PDR for new dwellings could also increase the risk of PDR being applied on top of PDR. For example, once constructed, new-build homes in rural areas could benefit from householder permitted development rights which could potentially result in further development. This could be limited through appropriate restrictions.