Most UK homes need low-carbon retrofitting, so the government must develop a coherent national programme, says Andrew Mellor
Low-carbon retrofit of the UK’s existing building stock will play a key role in meeting the Climate Change Act’s ambitious targets of 80 per cent reduction in CO2emissions over 1990 levels by 2050, but we do not want to see our housing stock covered in a blanket of insulated render.
The retrofit process could do a lot of damage to the appearance and technical performance of housing stock. Yet if a considered approach is taken, retrofit offers an opportunity to improve streetscapes, dwelling values and internal comfort.
The major challenge facing both the government and the housing sector is to develop a coherent national retrofitting programme and a funding model to finance it. In order to complete the volume of retrofits required within the timescale, a coordinated approach with standardised solutions is needed.
The vast majority of the country’s 26.65 million homes will need low-carbon retrofits, primarily thermal upgrades to the external fabric and more efficient heating systems. Replicable solutions will reduce the capital cost of retrofit, improve the quality of installation and provide a unified aesthetic where needed.
It will also minimise the construction programme which will be especially important when the dwelling is occupied, as the majority will be. Retrofit should be like shopfitting; fast, efficient and with a quality end product.
Standardisation must also allow choice for homeowners and landlords in how and when they fund retrofit and the specific improvements to their homes. Standard approaches can be adopted, but not necessarily identical solutions.
The standardised product may include the same material and systems, incorporating the same detailing, but variation is provided through different finishes, textures and colours. Measures that address climate change adaptation and improve indoor air quality should also be considered.
Existing buildings conceal many issues, and dwelling fabric and maintenance records are not always accurate. Even though sometimes intrusive, complete surveys at an early stage of the project can resolve design and construction issues up front and avoid adverse impacts on costs and programme.
Lessons from our recent Retrofit for the Future projects in Cambridge, Dartford and Sea Palling show that particular attention must be paid to supply lead times and quality control of installations by subcontractors. Some items have taken up to 16 weeks to reach site, particularly non-standard items such as triple-glazed high-performance windows.
On one of the Cambridge projects, the supplier was not initially able to provide the insulation at a depth required for the external wall insulation because it was not the current norm.
Correct installation of roof-mounted solar technologies is most effective if roof coverings are removed and panels installed in the roof plane to avoid structural issues. Where we have specified innovative technologies >> and materials, contractors have experienced problems with installation due to lack of product development for that particular use. Subcontractors have ignored the need to follow construction details which impacts the ultimate thermal performance of the dwelling.
Policy and legislation also need to be addressed. Each Local Authority has its own interpretation of Permitted Development Rights. Sometimes planning permission is required for external wall insulation on one project and not another, even though the only difference is location.
An industry accepted and approved software tool needs to be developed which facilitates input of dwelling survey information and the optimum low-carbon retrofit solution to be formulated. Such a tool would be able to provide technical support for the architect or designer leading to certification and avoid lengthy planning and building regulation applications.
The upcoming Energy Technologies Institute’s two-year ‘Thermal Efficiency’ study, which will establish an implementation plan for the retrofit of all homes in the UK, will capture recent industry experience to develop an implementation plan for low-carbon retrofit. If CO2 emissions reductions are to be achieved, residents must also be briefed on how to live in their retrofitted homes.
Andrew Mellor is environmental director at PRP Architects. Rick Burgess of PRP Architects will speak on standardisation in retrofit at BEST