The latest amendments to the UK Building Regulations Part L came into force on October 1, but what does that mean for you and your business? Richard Evans, sales director at Buderus, reviews the new elements of Part L2B covering non-domestic buildings.
'Most sections of the Building Regulations are usually changed every eight to 10 years. But it seems that in the last decade or so, there has been a flurry of amendments for those sections that concern the heating industry.

Each of these updates represents a step change in the energy efficiency of buildings. These changes are a reflection of improvements in technology, which in turn help to drive further improvements. The intention is that if similar step changes can be made in the coming years, we will eventually get to a situation where new buildings meet zero-carbon standards. The government is aiming to achieve this by 2019 in the case of non-domestic buildings and this is currently the all-important goal.

So, where are we now in relation to that target and what must we do next? One of the biggest changes in the new regulations is a 25 per cent reduction in the maximum emissions allowed for new buildings. U-Value requirements aren't changing, heating efficiencies are staying the same, the only difference is the 25 per cent reduction in the Target Emission Rate, but that is by no means straightforward.

The 25 per cent cut is going to be an average, based on the type of building being assessed - so some commercial developers will only need to reduce their emissions by 20 per cent, others by 30 per cent. It has been known for some time that particular commercial buildings fare better in the SBEM calculation than others. This system is an attempt to iron out this problem, while reducing the limits on emissions at the same time.

The right calculation

Although the approved documents for Part L2B were released at the end of April, full details of the changes to the National Calculation Method have only recently been released by the BRE. The next most significant change in the regulations is the requirement to submit calculations before construction starts using an approved software tool to show how the building 'as designed' will comply with the regulations.
A list of specifications to which the building is to be constructed must also be submitted to Building Control.


On completion, the 'as-built' building will need to be checked against the design specifications. Furthermore, there is a new requirement to report evidence of compliance.

Not just about the new

In recent years, much of the effort to improve building energy performance has focused on new buildings, but in any given year, only a small fraction of the building stock is replaced. It could be argued that relatively modest improvements to the existing building stock would have much greater impact than the move to make new buildings zero-carbon. However, building regulations aren't necessarily the best mechanism with which to push overall improvements to the existing building stock, as they only apply when building work is carried out.

While there are some tweaks, the overall message of both Approved Documents L1B and L2B remains the same: whenever you carry out building work, elements of this work should meet certain minimum standards. For example, when you replace a boiler, it should meet a certain minimum efficiency, and when you put in a new window, it should meet a certain maximum U-value. You don't have to carry out CO₂ emissions calculations, and you don't have to do airtightness testing, although you can choose to use such methods if you feel they will give you greater design flexibility.

What has come as a surprise to some people is that there has been very little expansion in the types of buildings that require consequential improvements. These are energy efficiency improvements that have to be carried out to the existing building as a result of building an extension or increasing the installed capacity of heating or cooling.

These were introduced in 2006 in response to the 2002 Energy Performance of Buildings Directive, and only apply to non-dwellings over 1000 m³. It is proposed that this requirement is extended to dwellings over 1000 m², which equates to a fairly small number of dwellings. Last year's proposals for a recast of the Energy Performance of Buildings Directive included removing this 1000 m² threshold altogether, so it's a bit of a surprise that the government is still retaining it.

Apart from this, everything else is as expected. We must now wait to see how initiatives like the Carbon Reduction Commitment and potentially the Renewable Heat Incentive or its equivalent are delivered before we can make an impact on reducing carbon emissions and improving efficiency within existing buildings.

• Copies of the complete Approved Part L document can be downloaded at www.communities.gov.uk