KJ Tait

Building Regulations Challenges

15 May 2024

With the Building Regulations being updated in England (Part L 2021), Wales (Part L 2022) and Scotland (Section 6 2022) over the last few years, it has become difficult to pass the compliance assessment for all building types.  The introduction of these regulations has also meant that the traditional methods of complying with these regulations has become a lot harder. 


It is essential that Best Practice is achieved on building fabric as there has been a significant strengthening of the U-values for the Notional Building.   When investigating methods to achieve compliance for a building, modellers will always look for ‘wins’ that could be made against the Notional Building, for example ensuring that the U-values for fabric are better than.   


Thermal Element  Part L  Section 6 
Walls (W/m2K)  0.18  0.15 
Floors (W/m2K)  0.15  0.13 
Roofs (W/m2K)  0.15  0.11 
Windows (W/m2K)  1.40  1.20 


However, in reality, the U-values above are hard to achieve.  Another aspect of the new regulations centres around non-repeating thermal bridges.  These should be calculated and if not, then 25% of the U-value of each thermal element is added back on.  For the Notional Building, the thermal bridges are set at 10%.  Therefore, even if we can achieve say 0.15 for an external wall, the Notional Building U-value will be 0.165W/m2K and the actual building 0.187W/m2K if we do not calculate the thermal bridges.


One building type where this has become a big issue is student residences where bedrooms are normally heated via electric panel heaters.  If the thermal bridges are not calculated then there is no ‘win’ to be had on the fabric, no ‘win’ to be had on the heating system and PV would be included on the Notional Building making compliance with the regulations extremely difficult. 


What is the answer?  On each project the Energy Engineer should be engaged as early as possible so the building can be modelled, and the correct advice given.  There are many different aspects to building design that are all interlinked such as complying with regulations, overheating and daylighting therefore ensuring you get the appropriate advice at the start of a project can save a lot of time, money and effort later on.