Part L 2021 – Existing non-domestic buildings in England

18 October 2021 Kingspan Insulation UK

The recent Future Building Standard consultation provides a key insight for the construction industry into how energy performance requirements for non-domestic buildings are likely to change over the next few years. Reducing emissions from existing non-domestic buildings will be essential to meet the country’s net-zero carbon commitments by 2050. In this blog, we look at how the latest changes to Part L of the Building Regulations will affect them.

What is new in Part L 2021 for existing non-domestic buildings?

In contrast with the extensive changes recommended for new non-domestic buildings in Part L 2021, the consultation includes only fairly minor updates in the fabric requirements for existing buildings. The minimum fabric requirements for new or replacement thermal elements have been tightened slightly (shown in the table below). Disappointingly, however, the requirements for renovated thermal elements are entirely unchanged from the existing version of Part L.
Element type Current new element limiting U-values (L1A 2013) Proposed 2021 new element area weighted limiting U-values
All roof types    
- pitched roof (sloping) 0.18 0.16
- pitched roof (horiz) 0.16 0.16
- flat roof 0.18 0.18
Walls 0.28 0.26
Floors 0.22 0.18
Swimming pool basin 0.25 0.25
Windows 1.60 or WER C 1.60 or WER B
Rooflights 1.80 2.20
Other windows, roof windows, curtain walling & pedestrian doors 1.80 1.60
Vehicle access and similar large doors 1.50 1.30
High usage entrance doors 3.50 3.00
Roof ventilators 3.50 3.00

This is a missed opportunity, as there was certainly room for improvements to those backstop requirements when undertaking re-roofing works at the very least. 

The consultation provides some more extensive changes for services in existing non-domestic buildings including:

•    when replacing fixed building services involves a fuel switch, the replacement should not have higher CO2 emissions or Primary Energy demand;
•    changes to the minimum seasonal efficiencies, minimum standards in air distribution, minimum standards for comfort cooling systems and minimum standards for Building Automation and Control Systems will also apply to installations on existing budlings;
•    where Building Regulations are triggered (such as by a building refurbishment) minimum efficacy proposals for lighting for new buildings will also apply to existing buildings; and
•    measures designed to make it simpler for low carbon heating to be installed in the future on new non-domestic buildings would similarly apply to existing buildings.


Minimum Energy Efficiency Standards (MEES) to drive improvement for existing buildings?

Whilst the on-going decarbonisation of our energy supply will go some way to reducing emissions from existing buildings, the changes proposed within Part L 2021 are unlikely to push existing properties to net-zero carbon performance. One alternative route the government may take to address this is through the tightening of the Minimum Energy Efficiency Standards (MEES).

MEES set minimum requirements that all rental properties requiring an Energy Performance Certificate (EPC) must meet in order to be placed on the rental market (subject to certain exemptions such as a 7-year payback period). At present, landlords cannot grant or renew tenancy on a building with an EPC of F or worse and from 1st April 2023 it will not be possible to rent properties with an EPC worse than E without an exemption.

In 2020, the Government ran a consultation looking at future trajectories for tightening MEES and in December’s Energy White Paper, the Government confirmed that the future trajectory for the non-domestic MEES will be EPC B by 2030, with an interim milestone of EPC C by 2027.

BEIS has published a further consultation on the implementation of the EPC B target. Feedback from the previous consultation has been considered and the latest consultation considers the need to: 
•    improve the implementation of the payback test and general enforcement of the PRS Regulations;
•    improve how the PRS Regulations currently apply to older buildings and to premises rented in a shell and core state;
•    better align the EPC requirements with the PRS Regulations; and 
•    focus on operational performance.
In theory, the proposals could offer a sensible approach for driving upgrades to the energy performance of these existing non-domestic properties. However, the government will first need to address criticism that the current scheme has been poorly policed and enforced and that additional funding may be required to make further upgrades cost effective.

A further criticism raised at the scheme was that the EPC certificate provides no measure of the actual energy use of a property. As a result, there is no formal measure of whether improvements introduced as a result of the standard are delivering the energy savings expected. The current consultation invites views on how smart meters could play a role in supporting landlords to meet the PRS Regulations as part of the next phase of smart meter rollout, which might help to address this.

With only minor changes proposed to Part L 2021 for existing non-domestic properties, measures such as tightening MEES will be essential if we are to meet our net-zero carbon goal.

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