Approved document L

[edit] Introduction

The Building Regulations set out requirements for specific aspects of building design and construction. Regulation 26 of the building regulations states that “Where a building is erected, it shall not exceed the target CO2 emission rate for the building…”, and Schedule 1 – Part L Conservation of fuel and power states that provision for conservation of fuel and power shall be made by: limiting heat gain and losses and providing building service which are efficient, have effective controls and are properly commissioned and that information is provided so that the building can be operated efficiently.

In 2026 Regulations were passed to make amendments to the Building Regulations 2010 (the 2010 Regulations) to implement the Future Homes and Buildings Standards of which Part L is core. These introduce the Future Homes and Buildings Standards aiming to ensure that new homes and non-domestic buildings are built with low carbon heating and high levels of energy efficiency. This is so that buildings constructed to these standards will not require retrofitting to become zero carbon in use as the electricity grid decarbonises. Approved Document F, Volume 1: relating to ventilation in dwellings was also amended as this is inherently related to efficiency in buildings. These Future Homes and Buildings Standards amendments were published on 24 March, 2026, coming into force on 24 March 2027, except regulations 3, 4, 6, 7, 8 and 9 that come into force for higher-risk building work and work to existing HRBs on 24 September 2027, subject to transitional provisions.

[edit] Approved documents

A series of approved documents provide general guidance on how different aspects of building design and construction can comply with the Building Regulations.Approved Document L: Conservation of fuel and power, deals with energy efficiency requirements.

There are four parts to Approved Document L::

• Approved Document L1A: Conservation of fuel and power (New dwellings).
• Approved Document L1B: Conservation of fuel and power (Existing dwellings).
• Approved Document L2A: Conservation of fuel and power (New buildings other than dwellings).
• Approved Document L2B: Conservation of fuel and power (Existing buildings other than dwellings).

[edit] Requirements

Key criteria described in Approved Document L include:

1. The designed carbon emission rate (Dwelling Emission Rate (DER) for self-contained dwellings and individual flats (excluding common areas) and Building Emission Rate (BER) for buildings other than dwellings) must not exceed the Target Emission Rate (TER) for a notional building of similar type, size and shape. Both are expressed in kgCO2/m2 per year.
2. Fixed building services should achieve a reasonable standard of energy efficiency. This is intended to prevent inappropriate trade-offs between different elements of the building. Minimum limiting parameters are set for key components of the building fabric to ensure that this is the case.
3. Solar gains should be limited.
4. As-built performance should be consistent with the DER. This includes air-permeability testing and appropriate commissioning of building services systems.
5. Provision should be made for energy efficient operation by providing the building owner with information enabling them to operate the building in a way that uses no more fuel and power than is reasonable. This might be done by the preparation of a building log book.
6. Limiting fabric parameters.

Before construction begins, a design stage calculation must be issued to the Building Control Body (BCB), setting out the TER, BER or DER and the specification for the building.

Within 5 days of the completion of the construction, a report must be issued to the BCB setting out the TER, BER or DER, any changes that have been made to the specification, and an energy performance certificate (EPC). These calculations require that an air-permeability test is carried out to ensure that the building envelope has been constructed to a suitably high level of workmanship so that air (and so heat) will not 'leak' through the building fabric. In addition, the BCB is likely to require a commissioning notice.

For buildings other than dwellings, the TER and BER can be calculated and the EPC produced by following the National Calculation Method (NCM). This can be done by using approved simulation software (Approved Dynamic Simulation Models (DSMs)) or by using the Simplified Building Energy Model (SBEM), a 'simplified' compliance tool developed by BRE, which has a user interface called iSBEM.

For dwellings, the Standard Assessment Procedure (SAP) should be followed. This can be done by using a computer program approved for SAP calculations by BRE on behalf of the government.

[edit] 2013 changes

The approved documents were upgraded on 6 April 2014, with a 6% increase in performance standards for new dwellings and 9% for non-domestic buildings. See 2013 changes to the approved documents for part L of the building regulations for more information.

The 2013 edition of approved document L1A for new dwellings, introduced Target Fabric Energy Efficiency rates (TFEE) to sit alongside Target Emission Rates. The TFEE is the minimum energy performance requirement for a new dwelling. The Dwelling Fabric Energy Efficiency (DFEE) rate is the actual energy performance of the new dwelling. The DFEE must not exceed the TFEE. See Target fabric energy efficiency rate for more information.

[edit] 2021 changes

On 15 December 2021 the government announced changes to the building regulations to the help UK deliver net zero. This includes a requirement for new homes to produce around 30% less CO2 than current standards and a 27% reduction of emissions from other new buildings, including offices and shops.

The changes follow a public consultation and come into effect from 15 June 2022, paving the way for the Future Homes and Buildings Standard in 2025, which will mean all future homes are net zero ready and will not need retrofitting.

Alongside amendments to the Building Regulations, 5 new Approved Documents were published:

• Approved Document L, volume 1: dwellings
• Approved Document L, volume 2: buildings other than dwellings
• Approved Document F, volume 1: dwellings
• Approved Document F, volume 2: buildings other than dwellings
• Approved Document O covering overheating

For more information see: Changes to approved document L and new approved document O.

[edit] Related articles on Designing Buildings

• 15 June 2022 changes to Approved Documents.
• 2013 changes to the approved documents for part L of the building regulations.
• Accredited construction details ACDs.
• Air permeability testing.
• Air tightness.
• Approved documents.
• Building emission rate.
• Building Research Establishment.
• Building log book.
• Building regulations.
• Changes to approved document L and new approved document O.
• Changes to Building Regulations Part F.
• Controlled fitting.
• Conventions for U-value calculations (2006 edition) BR 443.
• Dwelling emission rate.
• Dwelling fabric energy efficiency rate
• Energy performance certificate.
• Energy targets.
• Floor insulation.
• Future Buildings Standard shortcomings raised.
• Is hydrogen the heating fuel of the future?
• Lighting energy numeric indicator.
• Limiting fabric parameters.
• National Calculation Method.
• Non-domestic building services compliance guide.
• PAS 2038:2021 Retrofitting non-domestic buildings for improved energy efficiency
• Roof insulation.
• Simplified Building Energy Model.
• Standalone: The new way forward in non-domestic ventilation.
• Standard Assessment Procedure.
• Target emission rate.
• Target fabric energy efficiency rate.
• The effects of subframe systems on the overall thermal performance of external rainscreen walls.
• Thermal bridging and the Future Homes Standard.
• Zero carbon homes.
• Zero carbon non-domestic buildings.

[edit] External references

• Planning portal: Approved document L

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