Report comment

This article highlights the importance of human factors in the realisation of Green Deal savings. We agree, however, with the other comments above that it is very misleading as it relies on what is a flawed study.
The Verco study is based on use of SAP 2005 which is not used in the Green Deal. It ignores the existence of an Occupancy Assessment methodology which was specifically developed to adapt SAP 2009 for Green Deal purposes, and highlight to home owners the importance of specific usage patterns on the potential savings that can be achieved.
It also fails to apply in-use factors which significantly reduce SAP-predicted savings and uses bill data where only 41% is based on actual meter readings, with the rest based on energy company estimates, thereby rendering any conclusions based on the study highly dubious. In summary the Verco study uses a calculation that is significantly different to that which is embedded in the Green Deal system.
There are also a number of points of accuracy to make on the related article by Rick Wheal of Arup on the calculations required for a Green Deal assessment. The algorithms in SAP have evolved considerably over time and they certainly do not rely on data from the 1980s as stated. For example the occupancy, lights and appliances and water heating procedures have all been thoroughly reviewed and updated in the past few years.
Of course, SAP uses the same basic approach now as it always has done, and this is to be expected. The same would be true of any model with a similar purpose, including detailed building dynamic simulation models. Whilst human factors and lifestyle patterns may change over a period of time, the laws of physics do not change quite so often!