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

4. Assessment findings and mitigation

4.1. Introduction

4.1.1 This section presents the findings of the assessment of options for changes to PDR to support the provision of new homes. For each development type, the following sections outline the assessment findings; any potential mitigation or enhancement measures where relevant and applicable; and the likely secondary, cumulative and synergistic effects.

4.2. PDR for rural homes - extending existing PDR for the conversion of agricultural and forestry buildings

4.2.1 This section concerns options for the conversion of agricultural and forestry buildings to dwellings. The related assessment justification table can be found in Table 1 of Appendix A.

4.2.2 Agricultural buildings may form part of a formal architectural composition, or a more informal group of farm buildings linked through function. They may have fallen out of active use or be unsuitable for current agricultural practices.

4.2.3 Forestry buildings are buildings on land used for the purposes of forestry, including afforestation. Typically, many forestry buildings, like agricultural buildings, are a legacy of previous land use practices and may be unsuitable for current land management practices.

Existing permitted development rights

4.2.4 Classes 18B and 22A of the Town and Country Planning (General Permitted Development) (Scotland) Order 1992, as amended (the ‘GDPO’) currently allow for the change of use of an agricultural or forestry building to a dwelling, and certain building operations to affect that change of use. These are subject to a number of limitations and conditions, including:

• a cumulative maximum total of five dwellings can be created by virtue of the PDR on the agricultural unit or within an individual forestry building;
• the total floor space of any individual residential unit cannot exceed 150 square metres.

4.2.5 Prior notification/approval arrangements also apply for certain matters (design, natural light, transport, access, noise, contamination and flood risk).

Options considered

4.2.6 This SEA has considered the following options:

• No change in PDR
• Removal of existing PDR restriction on the cumulative number of units created
• Removal of existing PDR building footprint limits (including new ancillary buildings, removing 150 sqm area/unit, and extending external dimensions)
• Revision to existing PDR to exclude the conversion of buildings only within/on Scheduled Monument sites rather than on all sites of archaeological interest^[149]

4.2.7 For completeness, as the consultation invites views on whether any of the current locational restrictions in relation to Classes 18B and 22A should be removed, the following options have also been assessed:

• Extension of existing PDR by removing current locational restrictions for buildings on croft land
• Removing the locational restriction for a safety hazard area
• Removing the locational restriction for a military explosives storage area
• Removing the locational restriction for listed buildings
• Removing the locational restriction for buildings situated within the curtilage of a listed building

Assessment findings – no change to PDR

4.2.8 The existing requirement to apply for planning permission ensures that applications are determined in accordance with the development plan unless material considerations indicate otherwise. It supports the consideration of issues across the SEA topics. As such it gives rise to minor positive effects across all environmental topics.

Assessment findings – options for PDR changes

4.2.9 Across all options, there is potential for mixed effects on cultural heritage. There is a minor positive effect if buildings at risk are brought back into beneficial use, supporting their retention and ongoing maintenance. There is also potential for a negative effect as expanding PDR would remove the opportunity to cultural heritage through the planning application process.

4.2.10 Depending on which options are taken forward however, there is also potential for significant negative effects on cultural heritage:

• Removing the locational restriction within the curtilage of a listed building has potential to result in significant negative effects on cultural heritage as the conversion to residential use may impact a listed building or its setting. The requirement to apply for planning permission supports the general duty, placed on decision makers when considering whether to grant planning permission for development which affects a listed building, to have regard to the desirability of preserving the building or its setting.
• Excluding the conversion of buildings only within/on Scheduled Monument sites rather than on all sites of archaeological interest has potential to result in significant negative effects on cultural heritage related to the provision of underground services necessary to facilitate the conversion (e.g. water and sewerage connections) and potential loss of historic assets. The extent of this effect is uncertain, as there is no comprehensive data on the number or distribution of HERs in proximity to agricultural and forestry buildings. There is currently no land designated as an area of archaeological importance in Scotland.
• Removing development footprint limits has potential for minor negative effects on cultural heritage. Development may impact the appearance, structure or setting of the agricultural or forestry building. This is uncertain and will depend on the design of the development, and the sensitivity of the location. The potential effects would be in areas of heightened sensitivity such as Conservation Areas, Gardens and Designed Landscapes, Historic Battlefields, Scheduled Monuments, World Heritage Sites, and locations with archaeological interest. Listed building consent would continue to be required for works affecting listed buildings regardless of whether a planning application was required.

4.2.11 There is potential for significant negative effects on population and human health if options to remove the locational restrictions on PDR within a safety hazard area or military explosives storage area are taken forward. This is uncertain as the number of such sites in the vicinity of agricultural and forestry buildings is unknown.

4.2.12 All options have potential minor negative effects for biodiversity as a result of increased potential impacts on species including wild birds and bats which may nest or roost in buildings and forage in the surrounding landscape. This is uncertain and will depend on the sensitivity of the location and the value and vulnerability of the species and habitats affected.

4.2.13 All options have potential for minor negative effects on landscape and geodiversity where PDR supports the conversion of agricultural and forestry buildings leading to changes in landscape character. This effect would be greater in Local Landscape Areas, National Scenic Areas and National Parks, reflecting the greater sensitivity of these landscapes.

4.2.14 All options have potential for minor negative effects on soils where PDR supports the conversion of agricultural and forestry buildings which impact on valuable soil resources. There would also be a loss of opportunity to consider land affected by contamination through the planning application process, though this effect would be minimised where the existing prior notification/prior approval mechanism which supports the consideration of risks to occupiers of the proposed dwelling from contamination from the site continues to apply.

4.2.15 All options have potential to give rise to minor negative effects on water reflecting the vulnerability of residential use to flooding and the loss of opportunity to consider flood risk and surface water management through the planning application process. This effect would be minimised where existing prior notification/prior approval mechanisms which supports consideration of risk of flooding of the site continue to apply. This would however not consider the effect of the development on flood risk elsewhere, off-site. This effect is uncertain and will depend on the character of the area and its vulnerability to flooding. The potential for negative effects would be greater where existing PDR building footprint limits are removed. The opportunity to consider sustainable water sources for drinking water through the planning application process would also be lost.

4.2.16 All options have potential to give rise to minor mixed effects on material assets. Extending PDR can help support the sustainable management of existing assets as buildings are brought back into use and maintained, resulting in a minor positive effect. There would be loss of opportunity to consider the design or external appearance of the building through the planning application process though this effect would be minimised where existing prior notification/prior approval mechanisms which supports consideration of the design or external appearance of the building continue to apply.

4.2.17 Depending on which options are taken forward, there is potential for mixed effects on climatic factors.

• Removing the restriction on the cumulative number of units created may increase greenhouse gas emissions associated with reliance on private vehicles, including those powered by fossil fuels, leading to minor negative effects at a local level.
• Removing development footprint limits (including new ancillary buildings, removal of 150 sqm area/unit limit, and extending external dimensions) may further support the reuse and retention of existing buildings with minor positive effects.

4.2.18 Across all options, effects on air are considered to be negligible or unlikely.

Mitigation of negative effects

4.2.19 The following potential mitigation is identified:

• Consider introducing new or revised restrictions on PDR for conversions (e.g. in terms of a revised maximum number of units, footprint/height of new ancillary buildings, internal area of unit, area/height of external dimensions).
• Consider providing design guidance e.g. in relation to landscape, and cultural heritage and further promoting NatureScot guidance on Developing with Nature.
• Consider retaining prior notification/prior approval for contamination, adequate light, transport, access, noise, and design/external appearance.
• Consider amending the conditions of the PDR so that the matters on which prior approval can be required include the surface water management and the effect of the proposed development on flood risk elsewhere, in addition to flood risk on the site itself
• Consider introducing additional matters on which prior approval can be required for new or expanded PDR, to cover potential effects on sites of archaeological interest and/or sites listed in Historic Environment Records and listed buildings and their settings.
• Consider providing guidance on development in the vicinity of safety hazard areas and military explosives storage areas.
• Consider retaining the current restriction on converting buildings constructed after the introduction of Class 22A and Class 18B PDR (4 November 2019).

Secondary, cumulative and synergistic effects

4.2.20 The assessment has considered the likely effects of a range of options which, if implemented together could result in potential significant cumulative effects. The nature of these will depend on the types of changes that come forward and the locations in which they take place. It is however possible to draw a number of broader conclusions about the potential cumulative effects of changes in PDR for the conversion of agricultural and forestry buildings.

4.2.21 There is potential for significant negative cumulative effects on cultural heritage from options to extend PDR for the conversion of agricultural and forestry.

4.2.22 There is potential for significant negative cumulative effects on flood risk if options to remove existing PDR restriction on the cumulative number of units created are taken forward alongside options to remove existing PDR footprint limits.

4.2.23 Secondary effects may occur as a result of the effects on one issue resulting in effects on another. Impacts on soil for example can increase the risk of flooding. There may be reliance on private water supplies in some rural areas, with increased risk of water scarcity through cumulative impacts of development when taken together with the impacts of climate change. The precise nature of these effects will depend on the options selected as well as the locations in which development takes place.

4.2.24 Secondary, cumulative and synergistic effects resulting from options to extend PDR for conversion of agricultural and forestry buildings in combination with other development categories are discussed in Section 5.

4.3. PDR for rural homes – Introducing PDR for new homes in rural area

4.3.1 This section concerns options relating to new-build homes in rural areas. The related assessment justification can be found in Table 2 of Appendix A.

4.3.2 The Scottish Government core definition^[150] of rurality classifies areas with a population of fewer than 3,000 people as ‘rural’.

4.3.3 NPF4 defines ‘brownfield land’ as ‘land which has previously been developed. The term may cover vacant or derelict land, land occupied by redundant or unused buildings and developed land within the settlement boundary where further intensification of use is considered acceptable’.

Existing permitted development rights

4.3.4 With the exception of PDR for local authorities (Class 33 of the GPDO), there are currently no PDR for new-build homes.

Options considered

4.3.5 This SEA has considered the following options:

• No change in PDR
• Introducing PDR for the replacement of agricultural and forestry buildings in rural areas with new-build homes
• Introducing PDR for the replacement of any buildings in rural areas with new-build homes
• Introducing PDR in rural areas for new-build homes on previously developed land only
• Introducing PDR in rural areas for new-build homes on any land

Assessment findings – no change to PDR

4.3.6 The existing requirement to apply for planning permission ensures that applications are determined in accordance with the development plan unless material considerations indicate otherwise. It supports the consideration of issues across the SEA topics. As such it gives rise to minor positive effects across all environmental topics.

Assessment findings – other PDR options

4.3.7 The environmental effects of options to introduce PDR for new-build homes (whether on previously developed land or on any land) are considered to be greater than those for the replacement of existing buildings.

4.3.8 All options have potential significant negative effects for cultural heritage on both designated and undesignated heritage assets and their settings. The effects are uncertain. The scale and significance would vary depending on the sensitivity of the location and the heritage value of the assets affected.

4.3.9 Introducing PDR in rural areas for new-build homes (either on any land or previously developed land) has potential for significant negative effects for biodiversity, landscape and geodiversity, material assets, population and human health, soil and water. Scotland’s land use is dominated by agriculture and forestry, which together account for around 80% of total land cover, and therefore the potential magnitude of effects is large. There is also uncertainty associated with the sensitivity of the location, value of area effected and scale of development. Effects in designated areas are likely to be greater reflecting the sensitivity of these areas. In addition, ‘previously developed land’ has a broad scope. It may for example include land where there has never been a building, land where a building has been demolished or land which has become ‘naturalised’. This broad scope results in additional uncertainty in the probability of any effects and value and vulnerability of the area likely to be affected.

4.3.10 Introducing PDR for the replacement of buildings (agricultural and forestry or any buildings) has potential to give rise to minor negative effects on biodiversity, landscape and geodiversity, material assets, population and human health, soil, and water. There is also uncertainty associated with the sensitivity of the location, value of area affected and scale of development. Effects in designated areas are likely to be greater reflecting the sensitivity of these areas. The scale of these effects may reduce depending on any limitations or restrictions to be applied.

4.3.11 All options have potential for minor negative effects on climatic factors associated with increased reliance on private vehicles in rural areas.

4.3.12 Across all options, effects on air are considered to be negligible.

Mitigation of negative effects

4.3.13 The following potential mitigation is identified:

• Consider restricting the scope of PDR for new-build homes (e.g. in terms of number of units, footprint/height of any new ancillary buildings, internal area of unit, area of extensions).
• Consider excluding areas designated for landscape, cultural heritage and/or biodiversity reasons from new PDR or otherwise limiting the extent of areas in which new PDR would apply
• Consider excluding formally designated contaminated land sites from new PDR
• Consider providing design guidance e.g. in relation to landscape, cultural heritage and further promoting NatureScot guidance on Developing with Nature.
• Consider the introduction of prior notification/prior approval for new PDR

Secondary, cumulative and synergistic effects

4.3.14 The assessment has considered the likely effects of a range of options for PDR for new homes in rural areas. If all the possible options were implemented there may be significant negative cumulative effects on biodiversity, climatic factors, cultural heritage, landscape and geodiversity, material assets, population and human health, soils, and water. The nature and scale of these will depend on the types of changes that come forward and the locations in which they take place.

4.3.15 Secondary effects may occur as a result of the effects on one issue resulting in effects on another. Impacts on soil for example can increase the risk of flooding. There may be reliance on private water supplies in some rural areas, with increased risk of water scarcity through cumulative impacts of development when taken together with the impacts of climate change. The precise nature of these effects will depend on the options selected as well as the locations in which development takes place.

4.3.16 Secondary, cumulative and synergistic effects resulting from options to introduce PDR for new homes in rural areas in combination with other development categories are discussed in Section 5.

4.4. PDR for Town centre living – introducing PDR for town centre living

4.4.1 This section concerns options relating to PDR for town centre living. The related assessment justification can be found in Table 3 of Appendix A.

4.4.2 The consultation proposes that such PDR would not necessarily be restricted to town/city centre locations. It would however exclude certain types of buildings such as substantial commercial premises e.g. supermarkets; enclosed shopping centres and shops in “out of town” retail parks. The reason given for this is to avoid the potential for additional housing being created in unsuitable locations and buildings and which would not contribute to town centre living. PDR in substantial commercial premises such as supermarkets; enclosed shopping centres and shops in “out of town” retail parks are therefore not considered reasonable alternatives and are excluded from the SEA.

Existing permitted development rights

4.4.3 There is currently no existing PDR for the change of use of Shops, financial, professional and other services (Class 1A), Food and Drink (Class 3) uses, Business (Class 4), Storage or distribution (Class 6) uses, Assembly and leisure (Class 11) use or Sui Generis uses to residential use in any location.

Options considered

4.4.4 This SEA has considered the following options:

• No change in PDR
• Introducing PDR for change of use for ground floor Class 1A units to residential
• Introducing PDR for change of use for upper floors above Class 1A units to residential
• Introducing PDR for external alternations to facilitate conversion

Assessment findings – no change to PDR

4.4.5 The existing requirement to apply for planning permission ensures that applications are determined in accordance with the development plan unless material considerations indicate otherwise. It supports the consideration of issues across the SEA topics. As such it gives rise to minor positive effects across all environmental topics.

Assessment findings – other PDR options

4.4.6 All options have potential for minor negative effects on water reflecting the vulnerability of residential use to flooding, potential changes in impermeable surfaces from external alterations, and the loss of opportunity to consider flood risk and surface water management through the planning application process. This is uncertain and will depend on the character of the area and its vulnerability of the area to flooding.

4.4.7 Depending on which options are taken forward, there is potential for minor negative effects on cultural heritage. Effects would be greater in areas of heightened sensitivity such as Conservation Areas, and World Heritage Sites. The effects are uncertain and would vary depending on the sensitivity of the location and the heritage value of the assets affected. The impact to listed buildings is anticipated to be minor as the requirement to comply with other statutory processes would remain.

• Introducing PDR for changes of use (both options) has potential to result in minor mixed effects on cultural heritage. There is potential for a minor positive effect if buildings at risk are brought back into beneficial use, supporting their ongoing maintenance. There is also potential for minor negative effects where PDR impacts the setting of an asset. For ground floor changes of use there is also a potential negative effect where changes lead to ‘dead frontages’
• Introducing PDR for external alterations to facilitate conversion has potential to result in minor negative effects on cultural heritage from physical alterations to the buildings, where PDR impacts the setting of an asset.

4.4.8 Both changes of use options have potential for minor mixed effects on climatic factors. Encouraging the reuse and retention of existing buildings has a minor positive effect in terms of embodied carbon. Loss of shops and financial, professional and other services from town/city centres may have a negative effect on vehicle emissions if trade is displaced to out-of-town locations. Increased town centre living may have positive effects associated with less commuting and vehicle emissions. These effects are uncertain and will depend on the character of the area and the uptake of PDR.

4.4.9 Introducing PDR for external alterations has potential to result in minor negative effects on material assets as the opportunity provided by the existing requirement to apply for planning permission to consider sustainable design would be lost. Introducing PDR for change of use (both options) also has potential for minor positive effects on material assets as they could promote the sustainable management of existing assets as buildings are brought back into use and maintained.

4.4.10 Across all options effects on air, biodiversity, landscape and geodiversity, population and human health and soils are considered to be negligible or unlikely.

Mitigation of negative effects

• Consider restricting the scope of PDR for external alterations (e.g. in terms of footprint, or dimensions)
• Consider excluding designated areas from new PDR
• Consider the introduction of prior notification/prior approval
• Consider providing design guidance

Secondary, cumulative and synergistic effects

4.4.11 The assessment has considered the likely effects of a range of options which, if implemented together could result in potential significant cumulative effects. The nature of these will depend on the types of changes that come forward and the locations in which they take place.

4.4.12 There is potential for minor negative cumulative effects on cultural heritage were PDR for external alterations taken forward alongside either or both options for changes of use to residential. This is uncertain and would relate to the scale and nature of external alteration proposed. Increasing the proportion of residential dwellings may also change the character of an area.

4.4.13 Secondary, cumulative and synergistic effects resulting from options to introduce PDR for Town centre living in combination with other development categories are discussed in Section 5.

4.5. Householder PDR

4.5.1 This section presents the findings of the assessment of options for changes to householder PDR. It outlines the assessment findings and potential mitigation or enhancement measures where relevant and applicable for single storey ground floor extensions (Class 1A of the GPDO); ground floor extension of more than one storey (Class 1B of the GPDO); and roof enlargements (Class 1D of the GPDO).

4.5.2 The likely secondary, cumulative and synergistic effects for options across the above three classes are considered together at the end of this section. Related assessment justification tables can be found in Tables 4, 5 and 6 of Appendix A.

Extending PDR for single storey ground floor extensions – existing permitted development rights

4.5.3 Class 1A of the GDPO applies in all areas except in conservation areas. It does not apply in respect to flats or to dwellings created under Classes 18B or 22A of the GDPO (conversion of an agricultural or forestry building). Broadly and in summary, extensions must be located to the rear of a property (i.e. not in front of the principal elevation or side elevation where said elevation fronts a road), with a footprint no larger than the original house and resulting in no more than half the front or rear curtilage being developed. There are also limits on the height of the extension (4m, 3m to eaves) and further restrictions on dimensions where the proposed extension lies within 1m of the property boundary.

Options considered

4.5.4 This SEA considers the following options:

• No change in PDR
• Applying existing PDR for single storey ground floor extensions to Conservation Areas
• Removing the requirement for extensions to be to the rear of a property (i.e. not in front of the principal elevation or side elevation where said elevation fronts a road) - excluding in Conservation Areas
• Removing the requirement for extensions to be to the rear of a property (i.e. not in front of the principal elevation or side elevation where said elevation fronts a road) – in all areas
• Removing the restriction on the height of the eaves - excluding in Conservation Areas
• Removing the restriction on the height of the eaves – in all areas
• Removing the restriction on the height of any part of the development - excluding in Conservation Areas
• Removing the restriction on the height of any part of the development - excluding in Conservation Areas
• Removing the restriction on footprint relative to the size of the original dwellinghouse - excluding in Conservation Areas
• Removing the restriction on footprint relative to the size of original dwellinghouse – in all areas
• Removing the restriction on footprint relative to curtilage - excluding in Conservation Areas
• Removing the restriction on footprint relative to curtilage – in all areas
• Removing the restrictions on size within 1m of the boundary - excluding in Conservation Areas
• Removing the restrictions on size within 1m of boundary – in all areas

Assessment findings - no change to PDR

4.5.5 The existing requirement to apply for planning permission ensures that applications are determined in accordance with the development plan unless material considerations indicate otherwise. It supports the consideration of issues across the SEA topics. As such it gives rise to minor positive effects across all environmental topics.

Assessment findings – options for PDR changes

4.5.6 Depending on which options are taken forward, there is potential for significant negative effects on cultural heritage. This is uncertain and would depend on the sensitivity of location, design and scale of the extension. Impacts to listed buildings are anticipated to be minor as the requirement to comply with other statutory processes would remain.

• Allowing extended PDR within conservation areas has potential to result in significant negative effects on cultural heritage as the extended PDR may impact designated heritage assets and their settings, with increased potential for schemes that prominently impact on the appearance, structure and setting of buildings within conservation areas.
• Extending PDR outside conservation areas has potential to result in minor negative effects on cultural heritage. Single storey extensions could become more visible by virtue of their size (footprint, massing, height) or location (not at rear). Effects would be greater in Gardens and Designed Landscapes, World Heritage Sites reflecting the greater sensitivity of these assets
• Applying existing PDR to conservation areas has potential to result in minor negative effects on cultural heritage. Although there is potential for single storey ground floor extensions to impact appearance, structure and setting of buildings within conservation areas this would be limited by PDR being applicable only for extensions at the rear of the property and being limited in height and size relative to the original dwelling and its curtilage.

4.5.7 All options have potential for minor negative effects on biodiversity, flora and fauna where development impacts species, such as garden birds, and their habitats. This is uncertain and will depend on the sensitivity of the location and the value and vulnerability of the species and habitats affected. The option to remove current restrictions on where (within the curtilage of a dwelling) an extension can be built may also result in minor positive effects as it could promote greater flexibility to avoid features such as trees and shrubs.

4.5.8 All options have potential for minor negative effects on landscape and geodiversity where this leads to changes in landscape character, for example where properties are located on the edge of settlements or the open countryside. These effects would be greater in Local Landscape Areas, National Scenic Areas and National Parks, reflecting the greater sensitivity of these landscapes.

4.5.9 All options have potential for minor negative effects on soils where this leads to impacts on valuable soil resources.

4.5.10 All options have potential for minor negative effects on water relating to a potential increase in impermeable surfaces. This is uncertain and will depend on the character of the area and the vulnerability of the area to flooding

4.5.11 All options have potential for minor positive effects on material assets as they will result in the enlargement of existing properties, reducing the need to construct larger new properties.

4.5.12 Across all options, effects on air, climatic factors and population and human health are considered to be negligible or unlikely.

Mitigation of negative effects

4.5.13 The following potential mitigation is identified:

• Consider introducing new or revised restrictions on PDR (e.g. footprint relative to curtilage/original dwelling size, height, elevation).
• Consider providing design guidance (e.g. in relation to landscape, and cultural heritage and further promoting NatureScot guidance on Developing with Nature.)
• Consider introducing prior approval/prior notification for development within conservation areas (e.g. for external appearance/design)

Extending PDR for ground floor extensions of more than one storey – existing permitted development rights

4.5.14 Class 1B of the GPDO applies in all areas except in Conservation Areas. It does not apply with respect to flats or to dwellings created by Class 18B or 22A of the GPDO (conversion of an agricultural or forestry building). Broadly and in summary, under this PDR extensions must be located to the rear of a property (i.e. not in front of the principal elevation or side elevation where said elevation fronts a road) with no part of development within 10m of the boundary of the curtilage and with a footprint no larger than the existing house and resulting in no more than half the front or rear curtilage being developed. There are also limits on the height of the extension.

Options considered

4.5.15 This SEA considers the following options:

• No change in PDRs
• Applying existing PDRs to Conservation Areas
• Removing the requirement for extensions to be to the rear of a property (i.e. not in front of the principal elevation or side elevation where said elevation fronts a road) - excluding in Conservation Areas
• Removing the requirement for extensions to be to the rear of a property (i.e. not in front of the principal elevation or side elevation where said elevation fronts a road) - all in areas
• Removing the restriction on height - excluding in Conservation Areas
• Removing the restriction on height - in all areas
• Removing the restriction on footprint relative to size of original dwellinghouse - excluding in Conservation Areas
• Removing the restriction on footprint relative to size of original dwellinghouse – in all areas
• Removing the restriction on footprint relative to curtilage - excluding in Conservation Areas
• Removing the restriction on footprint relative to curtilage - in all areas
• Removing or reducing restrictions on size within 10m of boundary – excluding in Conservation Areas
• Removing or reducing restrictions on size within 10m of boundary - in all areas

Assessment findings – no change to PDR

4.5.16 The existing requirement to apply for planning permission ensures that applications are determined in accordance with the development plan unless material considerations indicate otherwise. It supports the consideration of issues across the SEA topics. As such it gives rise to minor positive effects across all environmental topics.

Assessment findings – options for PDR changes

4.5.17 Depending on which options are taken forward, there is potential for significant negative effects on cultural heritage. This is uncertain and would depend on the sensitivity of the location, design and scale of the extension. The impacts to listed buildings are anticipated to be minor as the requirement to comply with other statutory processes would remain

• Allowing extended PDR within conservation areas has potential to result in significant negative effects on cultural heritage as the extended PDR may impact designated heritage assets and their settings, with increased potential for schemes that prominently impact on the appearance, structure and setting of buildings within conservation areas.
• Extending PDR outside conservation areas has potential to result in minor negative effects on cultural heritage. Ground floor extensions of more than one storey could become more visible by virtue of their size (footprint, massing, height) or location (not at rear). Effects would be greater in Gardens and Designed Landscapes, World Heritage Site reflecting the greater sensitivity of these assets
• Applying existing PDR to conservation areas has potential to result in minor negative effects on cultural heritage. Although there is potential for ground floor extensions of more than one storey to impact the appearance, structure and setting of buildings within conservation areas this would be limited by PDR being applicable only for extensions at the rear of the property and being limited in height and size relative to the original dwelling and its curtilage

4.5.18 All options have potential for minor negative effects on biodiversity, flora and fauna where development impacts species, such as garden birds, and their habitats. This is uncertain and will depend on the sensitivity of the location and the value and vulnerability of the species and habitats affected. The option to remove current restrictions on where (within the curtilage of a dwelling) an extension can be built may also result in minor positive effects as it could promote greater flexibility to avoid features such as trees and shrubs.

4.5.19 All options have potential for minor negative effects on landscape and geodiversity where this leads to changes in landscape character, for example where properties are located on the edge of settlements or the open countryside. These effects would be greater in Local Landscape Areas, National Scenic Areas and National Parks, reflecting the greater sensitivity of these landscapes.

4.5.20 All options have potential for minor negative effects on soils where this leads to impacts on valuable soil resources.

4.5.21 All options have potential for minor negative effects on water relating to a potential increase in impermeable surfaces. This is uncertain and will depend on the character of the area and the vulnerability of the area to flooding

4.5.22 All options have potential for minor positive effects on material assets as they will result in the enlargement of existing properties, reducing the need to construct larger new properties.

4.5.23 Across all options, effects on air, climatic factors and population and human health are considered to be negligible or unlikely.

Mitigation of negative effects

4.5.24 The following potential mitigation is identified:

• Consider introducing new or revised restrictions on PDR (e.g. footprint relative to curtilage/original dwelling size, height, elevation).
• Consider providing design guidance (e.g. in relation to landscape, and cultural heritage and further promoting NatureScot guidance on Developing with Nature^[151]).
• Consider introducing prior approval/prior notification for development within conservation areas (e.g. for external appearance/design).

Extending PDR for roof enlargement – existing permitted development rights

4.5.25 Class 1D of the GPDO applies in all areas except in Conservation Areas. It does not apply with respect to flats or to dwellings created by Class 18B or 22A (conversion of an agricultural or forestry building). Broadly, and in summary, under this PDR roof enlargements must be located to the rear of a property (i.e. not in front of the principal elevation or side elevation where said elevation fronts a road), must not exceed more than half the total width of the roof and be more than 0.3 metres from the edge of the roof. There are also limits on the minimum distance to the boundary of the curtilage and height of the roof enlargement.

Options considered

4.5.26 This SEA considers the following options:

• No change in PDR
• Applying existing PDR to Conservation Areas
• Removing the requirement for roof enlargement to be to the rear of a property (i.e. not in front of the principal elevation or side elevation where said elevation fronts a road) - excluding in Conservation Areas
• Removing the requirement for roof enlargement to be to the rear of a property (i.e. not in front of the principal elevation or side elevation where said elevation fronts a road) – in all areas
• Allowing height enlargement higher than the existing dwelling house - excluding in Conservation Areas
• Allowing height enlargement higher than the existing dwelling house - in all areas
• Allowing roof enlargement covering more than half of the roof - excluding in Conservation Areas
• Allowing roof enlargement covering more than half of the roof - in all areas
• Removing the restriction on the distance between the enlargement and the edge of the roof - excluding in Conservation Areas
• Removing the restriction on the distance between the enlargement and the edge of the roof - in all areas
• Reducing or removing the requirement for at least 10m between enlargement and boundary - excluding in Conservation Areas
• Reducing or removing the requirement for at least 10m between enlargement and boundary - in all areas

Assessment findings – no change to PDR

4.5.27 The existing requirement to apply for planning permission ensures that applications are determined in accordance with the development plan unless material considerations indicate otherwise. It supports the consideration of issues across the SEA topics. As such it gives rise to minor positive effects across all environmental topics.

Assessment findings – options for PDR changes

4.5.28 Depending on which options are taken forward, there is potential for significant negative effects on cultural heritage. This is uncertain and would depend on the sensitivity of the location, design and scale of the roof alteration. The impacts to listed buildings are anticipated to be minor as the requirement to comply with other statutory processes would remain.

• Applying extended PDR within conservation areas has potential to result in significant negative effects on cultural heritage as the extended PDR may impact designated heritage assets and their settings, with increased potential for schemes that prominently impact on the appearance, structure and setting of buildings within conservation areas.
• Extending PDR outside conservation areas has potential to result minor negative effects on cultural heritage. Roof extensions could become more visible by virtue of their height or location (on the sides or front of properties/relative to the existing building and curtilage). Effects would be greater in Gardens and Designed Landscapes, Historic World Heritage Site reflecting the greater sensitivity of these assets.
• Applying existing PDR to conservation areas has potential to result in minor negative effects on cultural heritage. Although there is potential for roof extensions to impact the appearance, structure and setting of buildings within conservation areas this would be limited by PDR being applicable only for roof extensions at the rear of the property, not exceeding more than half the total width of the room and meeting the height and criteria and limitations.

4.5.29 All options have potential for minor negative effects on biodiversity, flora and fauna where development impacts species, such as garden birds and bats, and their habitats. This is uncertain and will depend on the sensitivity of the location and the value and vulnerability of the species and habitats affected.

4.5.30 All options have potential for minor negative effects on landscape and geodiversity where this leads to changes in the landscape character, for example where properties are located on the edge of settlements or the open countryside. These effects would be greater in Local Landscape Areas, National Scenic Areas and National Parks, reflecting the greater sensitivity of these landscapes.

4.5.31 All options have potential for minor positive effects on material assets as they will result in the enlargement of existing properties, reducing the need to construct larger new properties.

4.5.32 Across all options, effects on air, climatic factors, population and human health, soils and water are considered to be negligible or unlikely.

Mitigation of negative effects

4.5.33 The following potential mitigation is identified:

• Consider introducing new or revised restrictions on PDR (e.g. restriction on distance to edge of roof, height).
• Consider providing design guidance (e.g. in relation to landscape, and cultural heritage and further promoting NatureScot guidance on Developing with Nature^[152]).
• Consider introducing prior approval/prior notification for development within conservation areas (e.g. for external appearance/design).

Secondary, cumulative and synergistic effects

4.5.34 The assessment has considered the likely effects of a range of options which, if implemented together could result in potential significant cumulative effects. The nature of these effects will depend on the types of changes that come forward and the locations in which they take place. It is however possible to draw a number of broader conclusions about the potential cumulative effects of changes in PDR for householder development.

4.5.35 If all the possible options were implemented and extended PDR were applied to Conservation Areas, there is potential for significant negative cumulative effects on cultural heritage. Poorly designed or located developments could affect the quality of the built environment, particularly within conservation areas. The combination of extensions, roof enlargements, the addition of porches, ancillary buildings, decking and fencing could have a significant impact on the character and appearance of individual buildings and the wider townscape.

4.5.36 If all the possible options were implemented there may also be more minor negative cumulative effects on biodiversity, water and landscape and geodiversity.

4.5.37 Secondary, cumulative and synergistic effects resulting from options to extend PDR householder development in combination with other development categories are discussed in Section 5.

4.6. Low/zero carbon heating and cooling – Expanding PDR for domestic air source heat pumps

4.6.1 This section covers the installation of an air source heat pump (ASHP) on a dwelling or within the curtilage of a dwelling. The related assessment justification table can be found in Table 7 of Appendix A.

4.6.2 The potential proposals to change PDR would extend existing PDR for installation of ASHP on domestic premises. ASHP transfer heat from the outside air to the interior of a building, or vice versa. ASHP are similar in appearance to air conditioning units as they use a refrigerant system consisting of a vapour compressor and a condenser to extract heat in one place and release it at another. In domestic heating use, the heat extracted by ASHP is used to power radiators, underfloor heating systems, or warm air convectors and hot water supply. ASHP are usually located at ground level immediately adjacent to a building, or at roof level.

Existing permitted development rights

4.6.3 Class 6H of the GPDO permits the installation, alteration or replacement of an ASHP on a dwelling or within the curtilage of a dwelling.

4.6.4 Only one ASHP per building is permitted and the ASHP must not be at the front of the property (i.e. forward of a wall forming part of the principal or side elevation of a building where that elevation fronts a road), be more than 3m in height, or protrude by more than 1 metre from the outer surface of an external wall, roof plane, roof ridge or chimney of a dwelling.

4.6.5 This PDR does not apply in world heritage sites or within the curtilage of a listed building. Development is also not permitted on a dwelling within a Conservation Area unless the ASHP is located at ground floor level and on the rear elevation of the dwelling.

4.6.6 The proposal to revise the reference to MCS Planning Standards or equivalent by removing the wording “or equivalent” is for clarification purposes, so that it is clear that the installation must comply with the current MCS Planning Standard for ASHP is not considered a substantive change and therefore has been excluded from the SEA.

Options considered

4.6.7 The following options have been considered in the SEA:

• No change to PDR
• Removing the restriction for ASHPs within conservation areas
• Applying existing PDR within the curtilage of a listed building
• Applying existing PDR within world heritage sites
• Extending existing PDR to facilitate two ASHPs on detached houses - maintaining existing restrictions for listed buildings, world heritage sites and conservation areas
• Extending existing PDR to facilitate two ASHPs on detached houses – in all areas
• Extending existing PDR to facilitate heating and cooling - maintaining existing restrictions for listed buildings, world heritage sites and conservation areas
• Extending existing PDR to facilitate heating and cooling – in all areas

Assessment findings – no change to PDR

4.6.8 The existing requirement to apply for planning permission ensures that applications are determined in accordance with the development plan unless material considerations indicate otherwise. It supports the consideration of issues across the SEA topics. As such it gives rise to minor positive effects across all environmental topics.

Assessment findings – options for PDR changes

4.6.9 Depending on which options are taken forward, there is potential for significant negative effects on cultural heritage. This are uncertain and will depend on the size and siting of the ASHP, and the sensitivity of the location, and heritage value of the assets affected.

4.6.10 All options have potential to result in minor positive effects on climatic factors and material assets associated with the uptake of this type of technology.

4.6.11 Across all options, effects on air, biodiversity, landscape and geodiversity, population and human health, soils and water are considered to be negligible or unlikely.

Mitigation of negative effects

4.6.12 The following potential mitigation is identified:

• Consider providing design guidance (e.g. in relation cultural heritage and low/zero carbon energy)
• Consider maintaining restrictions or introducing prior approval/prior notification for PDR in conservation areas, listed buildings and world heritage sites

Secondary, cumulative and synergistic effects

4.6.13 Removing the restriction for ASHPs within conservation areas, applying existing PDR within the curtilage of a listed building or applying existing PDR within world heritage sites in combination with extending existing PDR to facilitate two heat pumps on detached house could have significant negative cumulative effects on cultural heritage.

4.6.14 Secondary, cumulative and synergistic effects resulting from options to extend PDR for domestic air source heat pumps in combination with other development categories are discussed in Section 5.

4.7. Low/zero carbon heating and cooling - Introducing PDR for connections to heat networks

4.7.1 This section covers air connection to heat networks for domestic and non-domestic properties. The related assessment justification table can be found in Table 8 of Appendix A.

Characteristics

4.7.2 The PDR options would allow for the installation (and subsequent repair and maintenance) of underground pipework and associated apparatus for the purposes of connecting to a heat network.

4.7.3 Heat networks supply heat from a central source to consumers, via a network of underground pipes carrying hot water. Heat is brought into each building through a ‘heat exchanger’. Individual properties wishing to connect to a heat network will require suitable pipework to be installed within their property. Associated equipment such as pumps are likely to be fitted within the building itself and therefore would not require planning permission.

4.7.4 The consultation outlines that any such PDR would be subject to a condition that the ground surface must be restored to its original condition or appearance following any work.

Existing permitted development rights

4.7.5 There are currently no PDR for the connection of individual buildings to heat networks.

Options considered

4.7.6 The following options have been considered in the SEA:

• No change to PDR
• Introduction of PDR for heat network connections from individual buildings

Assessment findings – Options for PDR changes

4.7.7 Introducing PDR has potential to result in minor negative effects on cultural heritage where below ground works impact heritage assets. This effect is uncertain and will depend on the siting and scale of the proposed development and the restoration of land.

4.7.8 Introducing PDR has potential to result in minor negative effect on soils where below ground works leads to impacts on valuable soil resources. This is uncertain and will depend on the siting and scale of proposed development, the value of areas affected and restoration of land following below ground works.

4.7.9 Introducing PDR has potential to result in minor positive effects on climatic factors and material assets associated with the uptake of this type of technology.

4.7.10 Effects on air, biodiversity, landscape and geodiversity, population and human health, and water are considered to be negligible or unlikely.

Mitigation of negative effects

4.7.11 The following potential mitigation is identified:

• Consider introducing conditions for the restoration of land following the installation of pipes.
• Consider restricting PDR or introducing prior notification/prior approval in sites of Archaeological Interest; Historic Gardens and Designed Landscapes, Historic Battlefields and World Heritage Sites.
• Consider providing design guidance (e.g. in relation to cultural heritage and low/zero carbon energy).