Reinventing Retrofit was published yesterday by Green Alliance, with support from the Zero Energy Buildings Catalyst (ZEBCat) programme, supported by the European Regional Development Fund.
This blog was first posted by Business Green.
In 2017, buildings were responsible for 22 per cent of the UK’s total carbon emissions, compared to just 19 per cent from electricity supply. With declining coal power generation and the rise in electric vehicles, the climate impact of buildings is becoming increasingly important in the effort to cut carbon emissions. The current housing stock represents 80 per cent of the houses that will be standing in 2050 and retrofitting them to be low carbon will be a major challenge for the future.
The two main alternative heat sources, electrification and hydrogen, face numerous barriers to uptake. To completely electrify home heating without changing the heat demand would require large amounts of electricity generation capacity (between 275GW and 463GW) at colder times of the year, and hydrogen is not expected to be viable until the 2030s. Also the cost of switching systems en masse is estimated to be in the range of £120-300bn. Consequently, in the shorter term, reducing emissions from buildings at any scale will have to be done by cutting heat demand.
Past UK domestic energy efficiency programmes have led to emission reductions, from 78MtCO2 in 1990 to 64MtCO2 in 2017, by targeting the easy-to-treat properties and lower cost options. The Carbon Emissions Reduction Target scheme (CERT) cost £34 per tonne of avoided CO2. But, as the easy wins have been won, with over 60 per cent of cavity walls and lofts now insulated, we need to move on to harder to treat, solid wall homes, which will cost a lot more. The current Energy Company Obligation efficiency scheme is costing £94 per tonne of CO2 saved. There’s no sign of any big ideas from the UK industry to improve this either, with innovation slowing down in the construction sector and productivity flat lining since 1994.
The cost-effective efficiency measures being employed now are expected to reduce building energy demand by an additional 25 per cent by 2035 (relative to 2015). Previous policies to encourage energy efficiency retrofits have focused on bringing bills down. Although this is a leading motivation, householders also care about aesthetics and want to avoid the hassle of building works. So any new approach to improving home energy efficiency will have to be more appealing to people as well as reduce emissions.
The Energiesprong – or ‘energy leap’ – technique being rolled out in the Netherlands is one possible solution. This new way of dealing with the problem of home energy efficiency at scale could be transformational for the UK, which has one of the least efficient housing stocks in Europe.
It is a one-step approach to improving energy efficiency in the home that involves attaching a highly thermally efficient façade to the walls and roof. The façade is manufactured offsite, speeding up installation, and an electric heat pump and roof solar panels are fitted at the same time, resulting in a drop of up to 90 per cent in heat demand and a house that produces as much electricity as it consumes. Over 1,300 successful net zero energy refurbishments have so far been carried out in the Netherlands, with over 14,000 more in the pipeline.
At least 11 million UK homes are estimated to be Energiesprong compatible, which is just over 40 per cent of the total housing stock. While the emissions reduced per house will vary, converting all of these homes would cut CO2 by around 37Mt, equivalent to taking 17 million cars off the UK’s roads.
It is estimated that upgrading 2.3 million compatible social homes would save 7MtC02e, which is over half the amount the Committee on Climate Change says is necessary to meet carbon reduction targets from 2028-32 (the fifth carbon budget period).
Integrating components, constructing materials offsite and mass production, mean that waste in the construction process is reduced by 90 per cent and labour productivity is increased by 75 per cent. A large scale revival in the retrofit industry by the Energiesprong method would also be a huge boost to the UK’s flagging construction sector.
Green Alliance suggests that the government allocates £120m in innovation support, on a ‘commit and review’ basis, to create a pipeline of 5,000 net zero energy homes. This should be dependent on industry bringing down costs from £75,000 per home (the current average) to the more affordable £35,000 per home, which could then be paid for via service contracts, without the need for further subsidy.
What is clear is that we can’t reduce the climate impact of our homes without some radical new steps being taken. Energiesprong is one potential answer. It could give many more people warmer, more comfortable homes, which, on a cold day in February, sounds like a very appealing plan.