Part L Building Regulations – Target emission rate
In a move to drive towards new government targets of zero carbon buildings by 2019, the revised Part L Building Regulations were released in October last year. The 2010 revision of this document requires an overall 25% reduction in building CO2 emissions compared with 2006.
Further revisions with associated reductions in CO2 emissions are expected in 2013, 2016 and 2019. One of the most fundamental changes to be introduced in the 2010 revision is the target emission rate.
How is the target emission rate for the building calculated?
The target emission rate (TER) is now calculated by applying a set of defined 2010 building envelope and service specifications to a building having identical dimensions and operations (as defined in the National Calculation Method). T
his set of specifications is known as the 2010 notional building and is embedded within the SBEM calculation and compliance methodology. The building designer has to then specify the actual building envelope and services such that the actual building CO2 emission rate is less than or equal to the target.
There is no relationship between the TER for a 2010 building and the TER for a 2006, however the 2010 Notional building specification was derived so that the average performance of the 2010 compliant buildings will be 25% better than 2006.
Do I have to specify or construct to the 2010 notional building values for my actual building?
No. The notional building specification is only for calculating the target emission rate. Approved document L specifies the worst allowable or back stop values, which the building designer can use.
The notional building specification can be used as a good starting point for the actual specification, however it has not been optimised for any building type and will almost certainly not be the most cost effective solution.
For larger buildings, specifying a higher level of air tightness, will allow the designer to reduce the U value requirements, which can result in significant cost savings. Achieving higher levels of air tightness, requires a well designed system and interface details from a reputable cladding system manufacturer, along with good site workmanship and attention to detail by the cladding installation contractor.
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