The 2010 version of the Building Regulations Approved document Part L is due for implementation on 1^st October. There are moves to delay this on the grounds that the national calculation methods (SAP for dwellings and SBEM for non-dwellings) are not sufficiently reliable to enable design for carbon reduction. SPRA recognises these problems but argues that any delay now will have implications for the overall carbon reduction target leading to ‘zero carbon’ (net, from buildings) by 2020.  SPRA believes that problems with the calculation method should be resolved between developers and their designers and the building control bodies but must not be allowed to slow the carbon reduction process because there are likely to be far more serious technical challenges ahead.