Further to Friday's controversial claims by the Royal Institute of Chartered Surveyors about long payback times for home energy efficiency measures, a commenter to the The Times' coverage ( http://www.timesonline.co.uk/tol/news/uk/science/article2648540.ece) has uncovered:

Spreadsheet of calculations:  http://www.rics.org/NR/rdonlyres/80F3366F-13A9-4B72-B20A-257830F8C642/0/BCISResearchonPaybackTimesforEPCs.xls

Press release:  http://www.rics.org/Property/Residentialproperty/Acquisitionanddisposalofresidentialproperty/Homebuyingreform/EPC_payback_times_121007.html

Incidentally the RICS have much more optimistic assessments in a past report,  http://www.rics.org/NR/rdonlyres/454DA30B-010E-4310-BF3B-99D32A879E29/0/Energy_Efficiency_RICSEU.pdf (April 2007) which notes:

"The quickest pay back times are associated with cavity wall and loft
insulation and energy efficient lighting.
• Loft insulation: - payback period 1 year
• Wall insulation: - payback period less than 2 years
• Wall insulation (attached to wall): - payback period 5-6 months
• Energy efficient lighting: - payback period 3 - 10 years"

whereas the EPC payback spreadsheet gives loft insulation payback time as 13 years (11 excluding VAT) and cavity wall insulation as 5 years (4 excluding VAT).

The RICS is right that not everyone can DIY such jobs or 'knows someone' to do them on the cheap, and it is absurd that VAT is levied on either the cost of materials or contractors' labour for such steps.

However their failure to put this nuance into their presentation led to its absence from several media reports, meaning many people got the wrong end of the stick.