This will affect heavily glazed extensions, major renovations, conversions and change of use developments for all domestic projects which are submitted to Building Control from April 2014 onwards. The biggest story in Part L1B is the proposed changes which HAVEN’T made it into the final Approved Document – namely Consequential Improvements and lower U-Values. In the consultation papers, it was suggested that anyone constructing an extension on their home would need to ringfence 10% of their total budget to be spent on improving the existing building. So that might involve upgrading the heating system, changing to double glazing or installing solar panels. This hit the headlines as a ‘Conservatory Tax’ and following lots of political debates on the issue it was decided not to put Consequential Improvements into Building Regulations (It does apply to large commercial extensions, but this has been in place for several years so shouldn't be a big shock to anyone).
Limiting U-Values remain the same
Elsewhere, limiting U-Values in Part L1B are NOT changing from the current values. There are different sets of U-Values depending on what you are doing – here’s a summary (which applies to England only). Maximum U-Values for extensions are 0.22 for floors, 0.28 for walls, 0.18 for roofs and 1.60 for windows. If you’re renovating a wall the maximum U-Value allowed is usually 0.30, 0.25 for floors and 0.18 for roofs, although there are some exceptions. There was talk that U-Values would be lowered further, but as the limiting U-Values for new builds (under Part L1A) are not as good as these, and given the current set of U-Values are already quite low, it was decided the benefit of making the UK’s extensions that little bit more efficient wouldn't balance against the additional cost in building materials.
So what is changing?
The way we calculate the carbon emission rates for buildings is changing. This is known as the ‘SAP Methodology’ and is the same calculation process which is used under Part L1A. Some of the key changes include more accurate measurements for heating and hot water, as well as localised data covering external temperatures, solar gains and wind speed. So even though you may notice a change in the way L1B reports are presented and calculated, the way that targets are calculated under L1B are not changing. This means, in theory, a specification which works under the current 2010 version of Part L1B should work just as well under the new L1B… although the proof is in the pudding with this claim, so you’ll have to wait until April before we can prove / disprove this! In some cases under L1B, you may receive a brand new report from your assessment company – a recommendations report. This should list cost-effective measures which you could apply to the existing building or heating / lighting systems to save on fuel bills and reduce carbon emissions. There would be no requirement for you to implement any of the details listed on the Recommendations Report – it exists purely to give you advice and some food for thought on how you can make your home more efficient in the future. For more details about Part L and how the changes may impact you, contact Energist UK on 08458 386 387 You can also follow us on Twitter @EnergistUK for regular updates or join the UK Building Regulations Newtork on LinkedIn.