Permitted development rights to support the provision of new homes

Yes, we 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) for the installation to be considered as permitted development. 

Yes, we 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. 

The current policy focus of permitted development rights in this area is to support the rollout of low carbon heating technologies. Allowing installations that only provide cooling would not contribute to this goal and would result in additional energy use without improving heating efficiency. We therefore agree that if a homeowner wishes to install an ASHP solely for cooling, this should be subject to a planning application.

As the consultation notes, permitting ASHPs to be used for heating and cooling would allow air to air heat pumps to benefit from the PDR, providing additional choice for consumers. As Scotland’s climate continues to change and the risk of overheating in homes increases, cooling is likely to become increasingly important to help protect householder health and wellbeing. 

However, if technologies that can heat as well as cool (such as air-to-air heat pumps) become more accessible through planning changes, it will be essential to ensure that households are supported to make informed decisions about cooling.

In some cases, passive cooling measures – such as shading, ventilation or improved insultation – may be sufficient to eliminate or reduce the need for mechanical cooling. Ensuring households are aware of these options could help to avoid unnecessary energy use and costs.

Yes, we 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.

We also recommend that planning policy be updated to include a presumption in favour of allowing more than two units on detached dwellinghouses, where there is no demonstrable impact on neighbour amenity. This would support Scotland’s net zero ambitions, help households with higher heating requirements and provide greater certainty for applicants navigating the planning system.

Yes, we 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.

We recognise the Scottish Government’s position that there is currently insufficient data and no clear methodology to support permitted development rights for multiple ASHPs in these contexts.

However, we believe it is important that work is undertaken to address these gaps – including the development of appropriate methodologies and evidence bases, even if initially focused on specific housing archetypes. This is particularly important given the growing interest in air-to-air systems.

These are typically split systems with a smaller external unit that could more readily be sited on a balcony than an equivalent air-to-water unit or possibly hung from an external wall. There may therefore be a technical potential to decarbonise whole blocks of flats through fitting multiple single-dwelling air-to-air systems.

Given that around 36% of homes in Scotland are flats, 18.6% are terraced and 22.8% are semi-detached, it is essential that planning frameworks evolve to support low carbon heating across all housing types – not just detached homes.

This could be implemented through a combination of improved planning guidance now, and further amendments to PDR over time as evidence is gathered. 

Yes, the PDR wording should include clarification that limitations on siting and number of heat pumps relates only to those systems that include an external heat exchanger. Internal heat pumps are now available, both for air-to-air and air-to-water systems, and these do not require an external unit.

Typically, there would be just two air vents on the external facade of the building and so planning permission would not be required in most instances. However, their existence should not preclude the fitting of additional systems with external units under PDR. 

Yes, we 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.

This should make it easier and quicker to connect individual buildings to heat networks, helping to expand heat networks and support climate change targets.