Jonathan Atkinson reports on the positive results of a deep retrofit programme that might inform future government energy efficiency policy.
At the 2015 AECB Conference in Sheffield, Jonathan Atkinson of Carbon Co-op and Marianne Heaslip of URBED reported on interim findings from our deep retrofit programme, Community Green Deal. A couple of years later we have collected sufficient data to make some conclusions and outline key learning from the programme.
The project set out to achieve high quality, deep retrofit, at scale and at a relatively affordable price. It was funded by DECC and the Greater Manchester Authority with the intention of testing key elements of a ‘Green Deal-like’ Pay-As-You-Save model which could inform future government programmes (should there be any!).
A target for us was to deliver packages of improvements that take homes as close as possible to Carbon Co-op’s proposed 2050 carbon reduction target of 17 kgCO2/m2.a. The target fabric space heat demand was to be no more than 60kWh/m2.a or less, aiming for 40kWh/m2.a (AECB Silver standard) as the ideal.
How it worked
We are a Greater Manchester-based community benefit society and acted as contractor and intermediary, aggregating demand and signing back to back contracts with 12 owner occupier householders and then with a single lead contractor.
Householders benefitted from bespoke whole house assessments (using an augmented version of full SAP), 0% interest loans (funded by DECC and repaid over 20 years) and where available ECO –a rate that at the time was actually useful! The success of the project though was in no small part due to the work of URBED, who as well as delivering assessments provided the architectural design work on the project, acted as contract administrator and generally helped Carbon Co-op navigate the frightening world of construction!
Whole house – top to bottom
Our approach in designing the retrofits was firmly whole house, fabric first with a wider view on sustainability, for example specifying wood fibre external wall insulation and timber framed triple glazed windows (courtesy of AECB stalwarts Green Building Store).
Householders spent between £20,000 and £60,000 each (average £40,000) on the retrofit, PV panels and associated fees – depending on the size of the house and the number of basic energy efficiency measures already in place.
Varying combinations of 15-20 measures were specified depending on the individual household requirements and priorities of householders, the following were widely installed:
- External wall insulation as appropriate; mostly woodfibre (for vapour permeability and all round sustainability)
- Internal wall insulation (as appropriate, often on front elevation), also vapour open
- Triple-glazed timber replacement windows
- New insulated doors
- Humidity controlled passive stack ventilation systems
- Loft insulation top up
- Floor insulation
- Air tightness works
- High-efficiency solar photovoltaic panels
- Low flow hot water fittings
- New efficient boilers were installed in the three homes that did not already have them.
Data collection from the University of Salford and Carbon Co-op member Dominic McCann demonstrated the project succeeded in its main aims. There was an average of 47% reduction in gas use and for the majority of the houses the PV panels generate approximately as much electricity as the household uses (though in practice self-consumption is lower).
Before retrofit, households had energy bills ranging from around £500 to £2,000 a year. After retrofit, these fell decisively, with households saving from £200 (off an already small bill) up to £650 per year. Adding in the income from the Feed-in Tariff from solar generation, savings effectively rose to between £800 and £1,100 per year for these homes.
Householders reported improvements in comfort and indoor conditions post retrofit, including:
- Homes are warmer, including first thing in the morning.
- They feel less damp and the air feels fresher.
- Homes are less draughty.
- Homes are cooler in summer when it’s hot
Retrofitting the UK’s homes will be an essential part of our progress towards meeting our climate change commitments and a whole house approach like the one used here should enable people to keep warmer and healthier while saving money on bills.
Community Green Deal indicated that the UK construction workforce is readily able to develop and deploy the specialist skills required to carry out this type of high-performance retrofit. However, the funding and administration of current government support for retrofit stands in the way of scaling this kind of intervention.
Whilst policy remains in stasis, Carbon Co-op continues to press ahead and is now offering householders retrofit training, ‘buddying’ opportunities and chances to network with contractors. This support has contributed to up to 50 more retrofits being independently procured by members. As a result the co-op is now building up a local supply chain of trusted contractors.
There is a huge amount of learning from the Community Green Deal project and we encourage AECB members to read more here.
Jonathan Atkinson, Carbon Co-op
Jonathan Atkinson is a board member and co-founder of Carbon Co-op, an innovative community energy enterprise based in Greater Manchester, focussed on energy efficiency, low carbon technologies and whole house retrofit. Since completing a degree in Environmental Science, his career has crossed boundaries and disciplines. He worked at two research co-ops, Ethical Consumer and Corporate Watch, and in 2002 co-founded UHC Collective, a multidisciplinary art and design project based in Manchester. In 2008, collaborating closely with technical partners URBED, he oversaw the development and establishment of Carbon Co-op and has since delivered much of its work as project manager. These have included Community Green Deal, a project delivering deep retrofit to owner occupiers at scale and an affordable prices and Nobel Grid, a European-wide smart grids projects to enable co-operatives and communities to take control of their energy systems.
© 2017: Jonathan Atkinson and the AECB (for Terms and Conditions click here)
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