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From January 2023, GLA guidance will result in new applications needing to enhance their energy efficiency specifications. All existing London Plan CO2 reduction targets will now apply over the Part L 2021 baseline, which in practice represents a tougher target than the previous Part L 2013 baseline.

The 10% Be Lean (i.e. energy efficiency) target when applied over Part L 2021 is likely to prove most challenging. In addition to a specification which is required to meet the minimum Part L 2021 fabric energy efficiency (FEE) standard, the following measures are likely to be required:

  • Higher performance MVHR systems (MVHR units with higher ventilation rates may also be required for Part O compliance, which may limit the efficiencies that can be achieved);
  • Low flow rates in showers (≤ 8 l/s).

In some cases, the FEE strategy may also require revisiting should the above enhancements be insufficient to meet the 10% reduction. However, as the 10% target is based on CO2 emissions, changes to the FEE strategy are best only adopted once opportunities to maximise improvements in services have been exhausted.