The UK’s Green Deal: a modelled case study impact review

Panel: 5B. Cutting the energy use of buildings: Policy and programmes

This is a peer-reviewed paper.

Authors:
Vicky Ingram, Heriot Watt University, United Kingdom
David Jenkins, Heriot Watt University, United Kingdom

Abstract

The UK Government’s most recent policy to combat rising carbon emissions is the Green Deal: aiming to reduce emissions from the existing building stock by providing loans to homeowners for energy efficiency improvements. The cost of the loan is paid back through electricity bills, and is related to the savings predicted for the chosen measure(s). The loan stays with the home, rather than the owner, so measures with a long payback are not prohibited providing they comply with the ‘Golden Rule’: payback must be less than the modelled savings. The savings are calculated using the Reduced data Standard Assessment Procedure (RdSAP), the accredited tool for Green Deal assessments and Energy Performance Certificate calculations. While an updated version of the RdSAP tool will be used for Green Deal calculations (using occupancy-related “in-use” factors to adjust estimated bill savings), there are still serious concerns around the ability of such a method to predict savings with enough accuracy to approximate regular monthly loan repayments that are less than real savings.

This paper applies Green Deal assessments to a number of case study dwellings that each has unique challenges to overcome in an effort to improve their energy performance. These challenges include the presence of solid walls and listed building status (restricting what work can be undertaken), though some case studies will be less hard-to-treat. The sensitivity of the calculation method is investigated to gain further understanding into the likely impact of the policy, and the validity of using the RdSAP method to estimate the savings will be assessed. Additionally, based on the findings, the problem of making the scheme attractive to both householder and loan provider will be discussed.

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