An explanation of the 2014 changes to ‘Part L’

It is around a year now since the ‘Part L’ set of the current UK building regulations was updated by the Department of Communities and Local Government (DCLG).

This article is targeted principally to those amongst you that “still haven’t looked” at the changes, or found time to consider how they might affect your day-to-day building operations, let alone your bottom line.  It also serves as a useful source of information (with links) on the subject.

‘Part L’ as we all know, or should know, is the UK Building Regulations Approved Document relating to Conservation of Fuel and Power – the one that deals with ‘energy-efficiency.’ Just to confuse us, its equivalent is Part F in Northern Ireland and it relates to Section 6 in Scotland.


When do the 2014 ’Part L’ changes apply and where are they applicable?

In order to paint a more complete picture regarding the changes occurring throughout the UK, the timing of parallel changes in Northern Ireland and Scotland and the scenario in Wales are also explained here to help those working in all these countries and across borders.

On 6th April 2014 ‘Part L’ replaced the 2010 version and its subsequent modifications.  So all contractors and builders, including the ‘Davids’ and ‘Goliaths’ of the industry, working in England finally need to get to grips with the changes.

The Welsh Government’s version of Part L has been in force since 31st July 2014 and a Technical Guidance document was published then too.

The Scottish Government Building Standards Division (BSD) has already published new guidance regarding Building Standards compliance from 1st October 2015, including revised Technical Handbooks.  

In Northern Ireland the updated Building (Amendments) Regulations 2014, (including the confusingly named Part F relating to Conservation of Fuel and Power) took effect 25th February 2014 and revised Technical Booklets were also published later.

By 8th December 2014 updated versions of both the Reduced Data Standard Assessment Procedures (RdSAP) 2012 and Standard Assessment Procedures (SAP) 2012 have also been published although the latter is not yet in force in Northern Ireland or Scotland.

What are the 2014 ‘Part L’ changes?

In England and Wales the changes to the Approved Document L - Conservation of fuel and power DCLG publication set includes the new 2013 editions of Approved Documents L1A and L2A and further amendments to the 2010 editions of Approved Documents L1B and L2B. These are available via the Planning Portal and should be read in conjunction with the guidance documents.

Apart from format changes, the revised ‘Part L’ set includes the following changes:


National Calculation Methodology

The new requirements see a major change in the way the National Calculation Methodology (NCM) works for new homes with the introduction of two new additional targets:

  • Dwelling Fabric Energy Efficiency (DFEE) Standards (kgCO/m².yr)
  • Target Fabric Energy Efficiency (TFEE) Standards (kWh/m².yr)

Target Emissions Rate and the ‘Elemental Recipe’

There is a change to the way the Target Emissions Rate (TER) (kgCO/m² yr) is produced.

The DCLG refers to this as the 'elemental recipe.'

This determines thermal efficiency through assessment and the aim is to meet their non-prescriptive ‘notional dwelling’ criteria including:

External Walls (W/m2K)                               - 0.18

Party Walls (W/m2K)                                    - 0.0

Floor (W/m2K)                                             - 0.13

Roof (W/m2K)                                              - 0.13

Windows, Roof Windows, Glazed

Rooflights, Glazed Doors (W/m2K)              - 1.4

Air tightness (m2/hr.m )                               - 5.0

The regulations suggest that some builders may prefer to adopt model design packages that the industry can make available on rather than engage in design themselves. However clients can also appoint professional consultants such as Architects and specialist Engineers to carefully integrate energy-efficient design criteria sought in the 2014 ‘part L’ early on in their building projects and consider options such as passivhaus design and off-site prefabrication assembly processes and the impact of lifecycle costing.

SAP Changes
The SAP rating now needs to be advertised in all new dwellings. SAP 2012 includes the specification of a notional dwelling in Appendix R. This is used for Energy Performance Certificates.

The steps outlined in The Welsh Government’s own version of ‘Part L’ published in 2014 in respect of new dwellings are very similar to those in England but there are some significant differences which will affect those who build across both sides of the border.

Northern Ireland
In Northern Ireland, the changes include consideration of high-efficiency alternatives, a definition of what 'renovation,' is including 'major renovation, ' clarification of protected buildings and exempted buildings policy.


The Scottish Government published a consultation report in July 2014 “Lower carbon buildings - a review of energy standards and guidance within Scottish building regulations.”

Why are the 2014 ‘Part L’ changes important?
‘Part L’ is at the forefront of the fight against climate change as it relates to the Conservation of Fuel and Power. This cause is of global significance and the European Performance of Buildings Directive (EPBD) has set a useful context for the technical changes needed in the UK.

The changes are a step towards achieving zero carbon homes by 2019.  Some say they don’t go far enough, others say they are ‘better than nothing,’ a step towards the Government meeting its commitment to making life simpler for house builders, contributing to UK emission reduction and assisting in reducing fuel bills.  Whichever way you look at it, the changes suggest the Government now appreciates there are several routes to achieving its zero carbon target and appreciates the role of construction industry professionals and issues such as airtightness can play in achieving this.

Clients are increasingly interested in reaching zero carbon and achieving performance far above the ‘lowest common denominator’ benchmark it sets and the associated assessment schemes.  It is therefore important for industry players to understand how they can meet, if not surpass, the target values.

In real terms the regulation changes give more emphasis to reducing heat loss through 'thermal bridges,' as U-values fall and airtightness levels increase. They also require designs to avoid solar gains. It is therefore now more critical than ever to consider these issues early on, even at the feasibiliity or concept design stage.

Importance to the residential sector

The changes are 6% up on the 2010 standards for new dwellings in terms of meeting CO2 targets.

Compliance targets vary according to house type to take advantage of cost-effective savings.

The partial relaxation of targets for homes built off the gas network, the ‘fuel factor’, stays at current levels to assist rural house builders.

House builders continue to be able to meet CO2 targets in a variety of ways but the emphasis of these changes is on building fabric. 



Importance to non-residential sector

The changes a 9% up on the 2010 standards for non-dwellings in terms of meeting CO2 targets.

Despite these steps, it is worth reiterating that the changes suggest that the industry needs to shift gear to championing new technology and alternative forms of construction, including off-site construction to achieve the carbon standards required from 2016 and take off to a zero carbon future.

How can 2014 ‘Part L’ changes can be accommodated?

The 2014 ‘Part L’ Approved Document set is supported by the 2007 set of 'robust' construction details, now known as "Accredited Construction Details (ACDs) for Part L"

They were developed to assist the construction industry achieve the performance standards required to demonstrate compliance with ‘Part L.’


By using them expensive on-site testing can be avoided.

The current details are grouped by generic construction types and available from the Planning Portal.

TER compliance

It is now possible to show TER compliance by building to the ‘elemental recipe,’ described earlier, although SAP calculations still have to be submitted to Building Control departments for approval.

Designing to reduce heat loss through 'thermal bridges’

The updated regulations focus on way of limiting air leakage and thermal bridging in construction, insulation continuity, minimising cold bridging and airtightness. Heat loss through thermal bridges can be reduced by building to the limiting U Values given in the ‘Elemental Recipe’ and increasing airtightness. The ‘backstop’ U values for flexing remain unchanged from the 2010 regulations.

‘Backstop’ U values:

Software models can be used to find the most effective flexing as long as U-values do not go below backstop values and do not exceed the DFEE.

Future Changes to watch out for!

Further review of Part L is possible in 2016 in order to set the requirements necessary to comply with the European Directive for all new buildings to be zero carbon by 2021. 

There are undoubtedly more changes to come and to watch out for that Qualitape will endeavor to keep you informed of.

                                                                                                 - Many thanks to Mary Bon RIBA -