Effective retrofit is crucial to decarbonising the UK's energy systems and is a major step towards achieving Net Zero. The AECB Retrofit Standards tackle our historic underperformance when upgrading buildings. UK construction must deliver better energy efficiency for a low carbon future.

The AECB Retrofit Standards allow for easy self certification and increasing comfort & energy performance; it engages and upskills construction professionals to adopt and deliver higher performance targets for retrofit projects.

The AECB Retrofit Standard Level 2 was previously called the AECB Retrofit Standard. However, an update will soon be launched to add a new AECB Retrofit Standard Level 1 option.

The AECB Retrofit Standard Level 2 encourages the UK construction industry to decarbonise. We must prioritise the retrofitting of existing buildings at scale to meet 2050 environmental targets, as outlined in the Paris Agreement. 

A low energy, deep retrofit must include robust energy efficiency measures to drive down carbon emissions, resulting in lower running costs. This will reduce fuel poverty and deliver greater and more cost-effective CO2 savings.

Landlords will also benefit from significantly reduced management overheads in well retrofitted properties.

The AECB Retrofit Standard Level 2 enables retrofitters to achieve improved buildings that enjoy:

  • A future-proofed increase in winter and summer internal comfort levels;
  • Better indoor air quality & numerous health benefits;
  • Low running costs with a minimal energy performance gap;
  • Retrofit strategies that are ‘economically optimised’ for owners and occupants;
  • Energy savings at reduced cost per tonne of CO2 saved;
  • Reduced risk of damage from excess moisture.

The AECB Retrofit Standard Level 2 is for those wishing to retrofit buildings to a high standard, and particularly for those committed to delivering Net Zero. A low carbon building is first and foremost an energy efficient building.

Our Standard promotes the delivery of Net Zero carbon retrofits, combining a whole house 'fabric first approach' with ambitious energy efficiency measures.

Individual self-builders and larger-scale developers can positively contribute
to a low-carbon future by adopting the AECB Retrofit Standard when improving their buildings.


Features of the AECB Retrofit Standard Level 2

The Retrofit Standard Level 2 Targets

The AECB Retrofit Standard Level 2 is primarily focused on improving the building fabric but access to low carbon heat needs to also be considered. 

The standard is achieved when a building meets the targets detailed below.
It must also meet the technical requirements outlined in the Retrofit Standard document. 

Watch our latest webinar on retrofit standards

The Retrofit Standard Level 2 Compliance

Compliance with the AECB Retrofit Standard Level 2 requires the building has been modelled in PHPP, construction quality has been verified and the supporting data has been publicly declared. Delivering the AECB Retrofit Standard Level 2 also relies upon minimising thermal bridges using a PHPP verification sheet and following MVHR and airtightness testing protocols.

The Self-Certification Process

The self certification approach eliminates external certification. Projects can be self-certified by the Client engaging an Architect/Engineer/other experienced consultant or a Contractor suitably experienced that demonstrates design conformance prior to commencing on site. For certification, evidence needs to be uploaded to the AECB Low Energy Building Database (LEBD).