So, Wales have released the details of their own version of Part L – The Conservation of Fuel and Power. No longer will Buildings in Wales sing to the tune of the English regulations. They can now strike a different chord in their quest to reduce CO2 emissions, fuel bills and global warming.

So how different will it be across the Welsh border?

For a start they have decided not to adopt the Fabric Energy Efficiency Standard (FEES) favoured in England. No messing about with two targets in SAP – the traditional single CO2 TER remains and fabric is taken care of by a set of mandatory limiting fabric U-values:

  • Wall 0.21
  • Floor 0.18
  • Roof 0.15

Well, I say taken care, actually the document states that even these values should only be considered as a starting point towards compliance.

The new Notional Building parameters are published in the document as they are in England, however, unlike England, the tighter mandatory limiting fabric values will limit the variations possible when a designer looks to fine tune the Welsh building envelope.

If you are an existing building and fancy stretching yourself with a little extension – beware as there are now consequences. In England Consequential Improvements were proposed, and kicked out of Part L, for the third time in a row. Not in Wales. At the first time of asking they are required if a dwelling is extended or converted by no more than 10m2.

Consequential Improvements measures include:

  • Loft Insulation to a level of 250mm
  • Installation of cavity wall insulation where possible
  • Upgrading the hot water cylinder insulation

So, a sensible set of measures and triggers from Wales – not the 10% cost of doing the extension work proposed in England that looked more like a tax and also looked more than a little tricky to implement.

Consequential Improvements…

…will also be more widely applied to Non-domestic buildings. Clearly, the value of taking to chance to improve the fabric of the existing structure whilst work is being done on an extension is a principle that Wales seem keen to adopt across the built environment.

When adding new thermal elements to non-domestic buildings the type of building needs to be considered. Those buildings which are ‘essentially domestic in character’ will have more stringent U-value requirements. So, for example, a care home where warmth and comfort will be higher up the agenda than a warehouse, will require an improved U-value of 0.21 rather than the usual 0.26 in the wall.

Generally then, the Welsh seem to have gone for a sensible Regulatory Part L song. Not as loud as first suggested when the original 40% CO2 reduction proposal was announced. It’s more acoustic now, perhaps an unplugged version of ‘The Road to L’……

2016 Zero Carbon Targets

With Zero Carbon looming in 2016 it remains to be seen if England, Scotland or Wales are truly in tune with the need to reduce CO2 and use less energy.

Ultimately the UK as a whole needs to sing from the same carbon reduction hymn sheet if it is to get close to hitting the CO2 reduction targets. We have to hope they take it seriously. This is no time to mime.

The Wales Part L Guide will be available to download soon. In the mean time, for more information on the UK Building Regulations and to follow the bus on the #InsulatingBritain roadshow visit

Or join in the conversation on Twitter by using the hashtag #InsulatingBritain!

Here is an infographic on the quick facts and figures for Part L 2014 Wales:

Part L 2014 Wales FINAL