the year of change


The Year of Change: Revisions to Parts F, J & L


Fast becoming known as the year of change, 2010 has also brought with it a raft of new updates to building regulations. With significant revisions to parts F, J and L coming into force Colin Blatchford-Brown, Building Control Manager at NHBC explains the implications this will have on house-building and the new measures that must be taken into consideration.


Part L – Making homes more energy efficient With just five months to go before the new requirements of Part L come into force, it is important that home builders understand how to meet the new requirements and help


make homes more airtight and, therefore, more energy efficient.


One of the main changes to Part L is the need for almost double the amount of on-site air permeability and pressure testing – under the new Part L, either three units or 50 per cent of each dwelling type per


site (whichever is the lower figure) will need to be tested. Untested units will also have to declare the average results of tested units +2.0 m3/(h.m2), effectively meaning that designs will have to be based on a value of 8.0 m3/(h.m2) to achieve compliance. Under regulation 20D, TER and DER information, together with calculations and specifications used to achieve the design CO2 emissions, will have to be submitted to building control before work starts on- site, and as built information will have to be submitted within five days of completion.


14 British Builder & Developer


New limiting U-values for building fabrics have also been introduced as part of the revisions. For the first time this also includes U- values for party walls, however as the TER calculation assumes a U-value of 0.0 W/m2.K, to attain full compliance additional fabric insulation will need to be provided elsewhere. It will also be necessary to consider party wall detailing in relation to acoustic and fire safety provision. Under the new Part L,


effective U-values for thermal bridges should be based on the length of each junction


and the relevant psi values from SAP 2009. New requirements for energy efficient light bulbs will also be coming into force, as well as the removal of the secondary heating penalty from SAP. Finally, it will be necessary to demonstrate how a building can meet energy efficiency requirements for shell and core units. TER / BER calculations will be based on efficiency assumptions for services to be installed, and will have to be submitted to building control before work starts


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