Permitted development rights to support the provision of new homes: consultation

4 Other considerations and options

Other types of accommodation

We are considering whether it would be appropriate for any new or expanded PDR for the creation of new homes to be subject to a condition prohibiting the use of the resultant property as a short-term let (e.g. commercial holiday accommodation). Such a condition would not prevent someone from subsequently applying to the planning authority for permission to use the property in such a way.

Question 18: Do you consider that any expanded PDR for rural homes (described in chapter 2) should be subject to a condition prohibiting the use of the new units for short-term letting? Yes / No / Unsure. Please explain your answer.

Question 19: Do you consider that any ‘town centre living’ PDR (described in chapter 3) should be subject to a condition prohibiting the use of the new units for short-term letting? Yes / No / Unsure. Please explain your answer.

Householder development

The GPDO sets out various classes of PDR that apply to dwellinghouses and allow for, amongst other things, extensions to the dwellinghouse and the addition of outbuildings associated with the use of the house. The PDR are subject to specific limits and conditions designed to safeguard neighbours’ amenity and maintain the character of the area. By their nature, these PDR apply to existing dwellinghouses rather than the creation of new residential units. Planning Circular 1/2024: Householder Permitted Development Rights provides further background. There may be potential for such development to contribute to measures intended to address the housing emergency by enabling homeowners to expand their properties to meet their needs without having to consider moving. Furthermore, the PDR reduce pressure on planning authorities by reducing the number of applications for planning permission.

The current PDR seek to strike a balance between facilitating householder development and retaining sufficient planning control over the impacts of such development. However, there may be scope to make adjustments to the PDR such as:

• Increasing the maximum ground area covered by the resulting building (currently restricted to no more than twice the ground area covered by the original dwellinghouse) that can be created,
• Amending the external dimension restrictions, for example in conservation areas,
• Increasing the amount of side and rear curtilage that can be developed under PDR,
• Amending the PDR for alterations to roofs to allow greater use of loft space.

Question 20: Do you consider that it would be appropriate to amend PDR for existing dwellinghouses, to allow homeowners to make better use of their existing properties? Yes / No / Unsure. Please explain your answer.

Streamlining and reducing application numbers

Introduction

We have identified some options for introducing new or amending existing PDR to avoid the need for planning applications for certain developments. Specifically, in relation to the installation of air source heat pumps (ASHPs) on domestic properties, and connections to heat networks. These potential changes to PDR would avoid the need for planning applications for those works in many cases. In turn, this would potentially help to enable planning authorities to focus on assessing and making decisions on planning applications, including those for new homes, more swiftly.

Potential to amend PDR for domestic air source heat pumps

To help facilitate and encourage the deployment of ASHPs, an existing PDR allows for the installation of ASHPs on domestic premises, subject to certain limitations and conditions.

Class 6H permits the installation, alteration or replacement of an ASHP on a dwelling or within the curtilage of a dwelling. The class does not differentiate between dwellinghouses or buildings containing flats: it is applicable to both. There are several restrictions on development under Class 6H, the key ones being:

• No more than one ASHP is permitted on, or within the curtilage of, any building containing a dwelling.
• If the ASHP is attached to a dwelling, no part of the ASHP (including housing etc.) can protrude more than 1m from the surface of any external wall or roof. Within a conservation area the ASHP must also be at ground floor level and on the rear elevation of the dwelling.
• If the ASHP is within the curtilage of a dwelling (including those within a conservation area), it cannot be forward of the front elevation or side elevation where that elevation fronts a road. Nor can the ASHP and associated equipment or housing exceed 3m in height.
• The class does not apply in a World Heritage Site or within the curtilage of a listed building.
• Any ASHP installed under the PDR must comply with the Microgeneration Certification Scheme (MCS) Planning Standards or equivalent.

In summer 2023, we consulted on potential additional PDR for domestic ASHPs. In that consultation we acknowledged potential concerns about noise impacts from ASHPs – in particular cumulative noise where multiple pumps are installed in close proximity. We also noted that research was commissioned by the UK Government on heat pump noise emissions. The findings of that research were published in November 2023^[3]. Subsequently, a consultation was launched on potential amendments to MCS 020.

In March this year, the updated MCS 020 standards were published. The update included separating the ASHP and the wind turbines planning standards into separate documents including (in relation to ASHP) Air Source Heat Pump Sound Calculation for Permitted Development Installations. MCS 020 a) now contains a methodology for including up to two ASHPs in a sound calculation.

As noted above, the current PDR require any ASHP installed under the PDR to “comply with the MCS Planning Standards or equivalent”. We consider that the relevant MCS Planning Standards are now MCS 020 a). We are considering revising this reference in the PDR, and removing the wording “or equivalent”, to make it clear that the installation must comply with MCS 020 a).

Question 21: Do you consider that the reference in the PDR for domestic air source heat pumps (ASHPs) should be revised to make it clear that the installation must comply with Microgeneration Certification Scheme (MCS) 020 a)? Yes / No / Unsure. Please explain your answer.

Following the updates to MCS 020, the UK Government amended the PDR that apply to domestic ASHPs in England. Amongst other things, the amendments mean that up to two ASHPs can be installed on detached dwellinghouses. In addition, they remove the previous restriction that ASHPs could only be used for heating purposes, and the PDR have been amended to allow for cooling and heating, but not solely for cooling purposes. This allows for air-to-air heat pumps to benefit from the PDR, providing additional choice for consumers. We consider that similar changes could appropriately be made to the equivalent PDR in Scotland.

The UK Government has also removed the previous restriction in England that the ASHP could not be installed under PDR if it was within one metre of the boundary of the property curtilage. In Scotland there is already no such restriction in the PDR.

Following the publication of MCS 20 a), we believe that it would be appropriate to amend the PDR to allow for the installation of up to two ASHPs on detached dwellinghouses (subject to all other restrictions of the PDR).

At this stage we do not consider there to be sufficient data or a clear methodology that would allow us to design appropriate PDR which would result in more than one ASHP to be installed on flatted buildings or on terraced or semi-detached properties, which are in close proximity to each other. We believe it is appropriate for planning authorities to continue to be able to assess such proposals on a case-by-case basis, including in relation to potential cumulative noise impacts. We currently therefore do not consider it appropriate to remove the current restrictions on ASHPs attached to such buildings. As such, any proposal that would result in more than one ASHP being attached to a dwelling (or more than two on a detached dwellinghouse) would still need to be the subject of a planning application.

Question 22: Do you consider that air source heat pumps (ASHPs) installed on domestic properties under PDR should be permitted to be used for heating and cooling but not solely cooling? Yes / No / Unsure. Please explain your answer.

Question 23: Do you consider that the PDR for domestic ASHPs in Scotland should be amended to allow for the installation of up to two ASHPs on a detached dwellinghouse? Yes / No / Unsure. Please explain your answer.

Question 24: Do you consider that proposals that would result in more than one ASHP being installed on flatted buildings or on terraced or semi-detached properties should continue to be assessed on a case-by-case basis by planning authorities? Yes / No / Unsure. Please explain your answer.

Question 25: Do you consider that any other changes should be made to the existing PDR for the installation of ASHPs in Scotland? Please explain your answer.

Potential for PDR for connections to heat networks

Heat networks supply heat from a central source to consumers, via a network of underground pipes carrying hot water. Heat networks can cover a large area or even an entire city or be fairly local, supplying only a small cluster of buildings. They avoid the need for an individual boiler or electric heater in each building.

The central heat source is often referred to as ‘the energy centre’. There are many possible technologies that can provide the input to a heat network. These include power stations, energy from waste facilities, industrial processes, combined heat and power plants, geothermal sources, electric boilers and solar thermal arrays.

Heat is brought into each building through a ‘heat exchanger’ which, for a residential connection, is about the same size as a domestic gas boiler. All the same heating controls are available and to the end user the central heating and hot water system works in the same way as a domestic gas-fired central heating system without the need for any combustion to take place inside the building. Heat networks can be various sizes and serve various combinations of building types. Heat networks can be extended over time, and new heat demands and heat sources can be added to the network.

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 not require planning permission. The pipes themselves would be expected to be installed underground, so the visual impact would be minimal once the installation is completed.

To facilitate such connections, we are considering the introduction of new PDR, covering residential and non-domestic premises, for the installation (and subsequent repair and maintenance) of underground pipework and associated apparatus for the purposes of connecting to a heat network. We do not currently believe that it would be necessary to exclude buildings in conservation areas or other areas such as national parks etc, although there may be a case for restricting works in World Heritage Site locations. A condition that the ground surface must be restored to its original condition or appearance following any work would ensure that the impacts on amenity and appearance of the area were addressed.

Question 26. Do you consider that it would be appropriate to have PDR for the installation (and subsequent repair and maintenance) of connections from individual buildings to heat networks? Yes / No / Unsure. Please explain your answer.