This is general guidance based on standard permitted development rights in England. Rules differ for listed buildings, conservation areas, and properties with Article 4 directions. Always confirm with your local planning authority before starting work.
Do I Need Planning Permission for an Air Source Heat Pump in Horsham?
Installing an air source heat pump (ASHP) to heat your home. ASHPs have specific permitted development rights under Part 14 of the GPDO, subject to noise and size conditions.
Planning in Horsham
90%
of planning applications granted
95%
decided within the statutory or agreed time
71%
of householder applications decided within 8 weeks
In the year to December 2025, Horsham decided 1,259 planning applications. 657 of these were householder projects such as extensions, loft conversions and outbuildings, of which 97% were granted.
Planning statistics: MHCLG planning application statistics, the year to December 2025. Conservation area and Article 4 data: planning.data.gov.uk, © Historic England / Crown copyright. Open Government Licence v3.0.
Important: Additional Restrictions May Apply in Horsham
Horsham has 40 conservation areas. These include Adversane Conservation Area, Amberley Conservation Area, Billingshurst Conservation Area, Blackstone Conservation Area, Bramber Conservation Area, Coldwaltham Conservation Area. If your property is in a conservation area, some or all permitted development rights may be restricted. For example, you may need planning permission for changes that would normally be permitted, including alterations to the roof, cladding, or extensions visible from a public highway.
Horsham has Article 4 directions in force. Article 4 directions remove specific permitted development rights in defined areas. If your property is covered by an Article 4 direction, you may need planning permission for work that would normally be permitted. Contact Horsham planning department to check whether an Article 4 direction applies to your property.
Check with Horsham planning department before starting work to confirm whether your property is affected by any special designations.
Permitted Development Rules for an Air Source Heat Pump
Generally permitted under Part 14, Class G of the GPDO. One air source heat pump is permitted per property, subject to conditions on size, noise, and position. The unit must comply with MCS planning standards for noise.
Conditions
- 1Only one heat pump per property under PD
- 2Must comply with MCS planning standards (MCS 020) for noise
- 3Must be at least 1m from the property boundary
- 4Must not be installed on a wall or roof slope fronting a highway (that is the principal or side elevation in designated areas)
- 5Must not be on a building listed or within the curtilage of a listed building
- 6Unit must be removed when no longer needed
Size and Dimension Limits
- Maximum volume of the unit: 0.6 cubic metres (including housing)
- Must be at least 1m from the property boundary
When Permitted Development Does Not Apply
- Not PD for listed buildings or within the curtilage of a listed building
- In designated areas, the unit must not be on a wall or roof forming the principal or side elevation visible from a highway
- Noise is a key consideration; complaints from neighbours can lead to a statutory nuisance investigation
- Only one ASHP per property under PD; a second requires planning permission
What About Building Regulations?
Building regulations approval is likely required
Building Regulations apply to the heating system installation. Covers Part L (conservation of fuel and power, including system efficiency), Part J (combustion appliances, if replacing a gas boiler), and Part P (electrical installation). Work should be carried out by an MCS-certified installer to qualify for the Boiler Upgrade Scheme grant.
Building regulations are separate from planning permission. Even if your project is permitted development, you may still need building regulations approval. Contact Horsham building control or use an approved inspector.
How to Apply in Horsham
If you need planning permission for your air source heat pump, you can apply through Horsham's planning department or via the national Planning Portal.
If your project is permitted development and you want written confirmation, you can apply for a Lawful Development Certificate (LDC) from Horsham. This provides proof that your project does not need planning permission, which can be helpful when selling your property.
What Happens If I Build Without Permission?
Low risk if installed within PD conditions. The most common issue is noise complaints from neighbours, which are dealt with under environmental health (statutory nuisance) legislation rather than planning enforcement. Installing a second ASHP without PP could attract enforcement.
Frequently Asked Questions
Do I need planning permission for an air source heat pump in Horsham?
Does an air source heat pump in Horsham need building regulations?
How do I apply for planning permission in Horsham?
How long does planning permission take in Horsham?
What percentage of planning applications does Horsham approve?
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