On Tue, 04 Jan 2011 23:08:39 +0000 David J wrote :
I cannot imagine one of those accredited assessors working their way
through all that detail/tables of the house construction, although
their s/w obviously reduces this to a manageable level...

SAP proper is used for new builds. For EPCs on existing homes, RD
[reduced data] SAP is used, with certain broad-brush assumptions made
which are appropriate for (say) 90% of homes. You can find these in
SAP2005 http://www.bre.co.uk/sap2005 Appendix S. The way in which the
actual rating number translates to a band A-G is in Table 15

--
Tony Bryer, Greentram: 'Software to build on' Melbourne, Australia
www.superbeam.co.uk www.eurobeam.co.uk www.greentram.com