|The aim of the project is to validate the cost, time and energy effectiveness of domestic retrofit across different house types, using an approach that could be employed to improve the energy efficiency of the vast majority of the existing 26 million homes in the UK which will still be in existence by 2050. The novel, mass-scale retrofit approach being tested was first developed in a deskbased ETI project (“Optimising Thermal Efficiency of Existing Housing”) completed in 2012, as part of the ETI Buildings programme. The 20-month long, £475,000 project will retrofit five types of domestic property, identified and prioritised in the earlier ETI project.
This report is Part 1 of the two-part summative report for the Energy Technology Institute’s “Domestic Retrofit Demonstration Project”, part of the “Smart Systems and Heat (SSH)” programme. The underpinning hypothesis for this project was that the Retrofit Approach can be developed to meet the targets set in the ETI’s “Optimising Thermal Efficiency of Existing Housing” project and viably deliver domestic retrofit to large numbers of dwellings.
The project identified the top 10 house typologies in the UK based on the typical total carbon dioxide emissions from each typology and the total number of that typology in the UK, i.e. the groups of houses by type which emit the most carbon dioxide emissions. Through modelling of the associated energy consumption reductions and quantification of the corresponding carbon dioxide emission savings, packages of retrofit measures where developed for each of the 10 housing groups.
A top-to-bottom retrofit installation process was developed, by analysing the most cost-effective package of retrofit measures suitable for a particular property; through to installation with the minimum disruption to the householder. The skills required of the workers in the installation team were identified as well as the optimum material distribution networks to supply them with exactly what is required and when. It was determined that time and cost is wasted due to the multiple trades visiting a house to undertake retrofit work, often in sequence over many weeks. Besides the impact this has on increasing costs, and lengthening installation programmes, it has a disruption impact on householders. It was therefore proposed that a multi-skilled team of 4 people should be used to complete work on individual homes. That team would not rely on external trades to complete the work and would undertake the whole work to each home before moving to another home.
The Performance Targets proposed by the team were:
The package of retrofit measures along with the supply chain delivery plans plus the multi-skilled installation team solution developed in the project are referred to as the ‘Retrofit Approach’ in thesereports. Building on the mass-scale whole house retrofit approach that was developed in the desk-based OTEoEH study, ETI decided to run a demonstrator project to trial the developed Retrofit Approach on five occupied houses. The demonstration project aimed to validate the approach in relation to the cost, time and energy effectiveness of the RetroFixTM and RetroPlusTM packages. PRP led the project with partner Peabody, supported by subcontractor Total Flow, an insulation manufacturer and a national construction contractor for the retrofit of four houses in London and a regional construction contractor for one home in the North of England. The ETI selected five house types, which were representative of the top fivetypology groups of the ten identified in the OTEoEH project. The consortium undertook analysis of the survey, design and installation processes as well as the resulting performance of the retrofit installations including the gathering of quantitative data from each house and qualitative feedback from the installation team and householders.
- RetroFix™: Installation period - maximum two weeks; capital cost of £10,000; primary energy consumption reduction of 25% - 40%
- RetroPlus™: Installation period - maximum three weeks; capital cost of £15,000 - £20,000; primary energy consumption reduction of 40% - 60%
The demonstration project also trialled a test developed by Loughborough University which analyses the amount of heat energy usedby a home prior to and after retrofit.