Changes to Part L1A

Updates to Part L1A – Consultation Results

The results of the consultation into the uplift in Part L standards have now been released. Whilst not final, these give a strong indication of the direction in which things are heading…


  • Implementation June 2022
  • 31% reduction in carbon from existing standards
  • A new ‘energy’ compliance metric in addition to the existing carbon/fabric targets
  • Planners can still go above and beyond e.g. London Plan


  • Will apply to projects with their initial notice submitted from June 2022 onwards
  • Any project whereby the initial notice is before June 2022 will be judged on SAP 2012 still
  • However, this is on the basis of commencement of work for EACH BUILDING by June 2023 (e.g. foundations, piling and/or drainage)

compliance matrix

  • Primary Energy: a new metric aimed at avoiding high running costs
  • Carbon Emissions (DER)
  • Fabric Efficiency (DFEE)

Notional specification

  • Targets generated against below specification
  • Significant uplift in standards particularly for external walls
  • 150mm Cavity or 100mm with high performing rigid insulation likely to be required

Fabric Element



1.2 Wm².K


1.0 Wm².K

External Walls

0.18 Wm².K


0.11 Wm².K


0.13 Wm².K

Air Permeability

5m³/(h.m²) @50Pa


Two main options for compliance;

  • Gas boiler with solar PV (Kw requirement 6.15% of GF area) & Waste Water Heat Recovery 
  • Air Source Heat Pump to provide space/water heating 

Other key points

  • Every plot to be air tested (no sample testing)
  • Photographic evidence throughout project required  
  • More comprehensive overheating analysis 

UKBC will seek to inform clients of any further changes as and when they are announced. 

A final Part L document is expected to be released in early 2022.

Get ready for the significant changes to the Part L1A of the Building Regulations by using our SAP 10 Consultancy Service.

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