Whichever way you look at it, decarbonising the UK’s housing stock is a gargantuan task. To meet the government’s ‘clean growth strategy’ goals to move all housing stock to EPC ‘grade C’ by 2035 will require homes to be upgraded at a rate of one every two. That would be difficult enough if you were mass-producing identical products, but the wide range of housing stock and financing options for retrofit in the UK means a tailored approach to assessing and upgrading homes is needed, and RSLs are finding that the data they hold on their homes needs massive improvement.
Several housing providers who have already invested significant effort in developing energy strategies are seeing the problem at first hand. Lee Revell, innovation lead at Halton Housing, said, “Although we hold high-level asset data, it doesn’t give us a reliable picture of the thermal performance of homes. Without robust data upfront, it can be difficult to identify which homes are in most need and which could be eligible for green funding without individual detailed assessments. So the question is, how do we get quicker and better at that process?”
It’s widely accepted that, despite the best efforts around quality assurance, there are problems with energy performance certificates (only 3 per cent of responses to a recent consultation from BEIS thought that EPCs were reliable). But EPCs (and the SAP that underpins them) are still valuable as an audit of housing stock. They are likely to remain as the main benchmark by which progress is measured, so the pressure is now on to find solutions that enhance EPC and survey data to produce retrofit action plans which deliver reliably.
Measure building performance, don’t model it
Part of the answer lies with better data from the homes themselves. An emerging range of solutions are using data from sources such as smart meters, retrofitted sensors, home monitors or thermostats to record the environment in homes.
Combined, these data streams can produce powerful, accurate measurements of a home’s performance, including a direct measurement of heat-loss from the fabric of the building. The data can be collected as part of a standard survey, retrofit or EPC assessment visit using small suites of sensors which can be deployed in any home and which provides a robust figure for heat-loss, regardless of housing type or occupancy.
Linc Cymru is one housing provider considering the new approach. Linc Cymru’s planned maintenance and compliance manager, Henry Simms, said, “Our ambition is to retrofit the majority of stock to SAP92 by 2030. We see our stock-condition surveys being evolved to include ‘whole house’ assessments by retrofit assessors; our existing approach is too focused on the condition of components and can miss fabric defects.”
Direct measurement enhances SAP ratings by getting around the stubborn problems of hidden defects and defaults to key assumptions that can reduce confidence in the calculation. It also allows comparison of a home’s performance before and after interventions to demonstrate which products have the greatest impact.
An emerging ecosystem
Better, faster measurements like these close the performance gap and go a long way towards making sure that improvements deliver what they promise. It’s also an underpinning technology that fits into a wider ecosystem of tools which promise fast, effective decision-making on energy-efficiency investments.
These tools have been available for several years but are now seeing rapid development as more housing providers establish their strategies for delivering ‘net zero’. They include bottom-up tools, such as digital twins or data-led, on-site assessments, or top-down tools that mine existing data sources to identify segments of the housing stock that could benefit from specific measures.
Top-down or bottom-up?
Bottom-up tools start from a position of deep understanding of each individual home to build action plans to upgrade in line with a housing provider’s strategy. EPCs are just the starting point for an exercise that involves detailed surveys and data-led diagnostics on each building’s performance.
Sero Homes are developing such a toolset, Pathways to Retrofit, to support the mass decarbonisation of homes. Sero’s toolset enables homes to be forecast into future energy-grid scenarios, using a fabric-first approach which allows them to be designed to both support and benefit from significant decarbonisation works at a grid level. The goal is to let the grid decarbonise more effectively while making the true decarbonisation of housing stock easier and cheaper.
Sero’s co-founder, Andy Sutton, said, “Homes need to decarbonise quickly, but over a number of years, so the Pathways to Zero approach allows for coordinated interventions in a series of logical steps. This means upgrades and improvements at the end-of-life, not before, and in sequences that work with the residents and owners.”
In contrast, top-down tools mine the wealth of data already held by housing providers to identify opportunities for groups of homes, providing a rapid way to test-drive a wide range of retrofit options. This is an important first step for turning energy strategies into action.
Parity Projects’ business development manager, Liz Lainé, who provide Portfolio (formerly CROHM), said, “Net-zero goals have put more pressure on housing providers to develop appropriate phased plans for improvement. Using existing data can give a clear picture on what measures should be done first, plus their costs, and it can also identify cases where data is less reliable or the course of action is less clear, so additional assessments can be included as part of the programme of works.”
Halton Housing’s Revell said, “Technology is enabling us to be cleverer about where we spend to have greatest impact. This is a good thing because the money is getting tighter for everyone yet the requirements just get higher and higher.”
Clear pathways for sustainability
A clear pathway is emerging for sustainability strategies among housing providers, with tools to inform energy strategy, prioritise opportunities and fit pathways for improvement to a range of future energy options. Driven by new types of data, such tools will help housing providers find the pathways to zero carbon and to better, warmer homes for tenants.
Hermione Crease is the commercial director for Purrmetrix.
