Flaws in the government’s Green Deal assessment model have been highlighted in a new retrofit report from Affinity Sutton Housing Group.
FutureFit, which follows on from a 2011 report, monitored households where retrofitting work and/or energy advice had been given in order to understand the actual impact on residents’ bills.
But in 75% of cases, the Standard Assessment Procedure (SAP) overestimated the savings – on average by 77%. The SAP software tool is central to the Green Deal assessment process.
The report found that 61% of homes did save energy as a result of retrofit works, but only 25% of homes had results consistent with the SAP modelling.
"Until a clear and transparent method is implemented for customers to identify and understand their energy use, the success of a scheme like the Green Deal will be hard to measure."
Jeremy Kape, Affinity Sutton
Commenting on the findings, Affinity Group chief executive Keith Exford said: “The report highlights the unpredictability of an individual household’s energy consumption and the challenge in tracking how much energy anyone actually uses from one year to the next. It also flags the potentially serious consequences of using the Standard Assessment Procedure as a modelling tool for retrofit in existing homes.
“Crucially though, it shows that retrofit does work and that taking a fabric first approach can have a real impact on a household’s gas bills. The results also start to support the use of lifestyle advice around reducing energy use in the home.”
Affinity director Jeremy Kape added: “The second stage of the project explains our decision not to support the Green Deal, as we believe that debts being built up by residents for energy improvement work would not necessarily be matched by equivalent savings in their bills.
“FutureFit has found that SAP is not an accurate modelling tool for existing homes. Some steps have been taken to combat this inaccuracy in the Green Deal assessment process, but these are unlikely to fully resolve the issue. This makes the Green Deal a lottery for our residents. A few may benefit, and even fewer may do better than expected, but the majority are likely to lose out with energy savings less than the annual Green Deal payments.
“Customers of a scheme such as the Green Deal would expect to see either savings on their bills or for their bills to stay the same once a charge has been added. Tracking the actual impact of any works in reality is very difficult. This means that people may end up feeling worse off after any works, even if they have in fact made savings. Until a clear and transparent method is implemented for customers to identify and understand their energy use, the success of a scheme like the Green Deal will be hard to measure.”
Affinity Sutton says it will continue to work with the government on developing a Pay as You Save mechanism that works in social housing.
“We also recognise the key role that the Green Deal has to play in funding retrofit in the future and, despite our current concerns, we remain open to working with the policy in the future,” said Kape.
