TwentyCi has today warned energy-efficient homes across the UK may be more vulnerable to long-term climate risks than their less energy-efficient counterparts, according to new analysis.
Its findings show that energy-efficient homes (EPC A–C) are collectively more likely to face high flood and subsidence risk than less efficient properties (D–G). In addition, nearly 9.5 million energy-efficient homes (EPC B rated) are projected to face significant exposure to either flooding or subsidence by 2055, highlighting a major and often overlooked risk within the UK housing market.
Energy efficiency ≠ physical resilience
The UK housing stock is heavily concentrated in the middle of the EPC scale, with 37% of properties rated D and 35% rated C. However, when this distribution is compared against physical risk indicators, a more complex and potentially concerning picture emerges.
EPC G-rated homes are currently the most exposed to flood risk, with 5.65% already classified as high risk, rising to 6.94% by 2055. Yet unexpectedly, B-rated homes - considered relatively energy efficient - have the second-highest flood exposure, with 5.27% currently at high risk, increasing to 6.52% by 2055. When extrapolated nationally, this equates to more than two million properties.
More broadly, energy-efficient homes (EPC A–C) are collectively more likely to face high flood risk than less efficient properties (D–G).
When it comes to subsidence, B-rated properties rank as the most exposed, with 6.74% currently at risk of subsidence. This figure is projected to rise sharply to 23.29% by 2055, impacting an estimated 7.4 million homes.
As with flooding, higher EPC-rated properties (A–C) show greater overall exposure to subsidence risk compared to their less energy-efficient counterparts.
Coastal erosion risk more closely follows EPC distribution, with G-rated homes most exposed (0.09%), followed by F-rated properties (0.04%). However, although smaller in scale, these risks can be catastrophic, often resulting in total property loss.
“While Energy Performance Certificate (EPC) ratings remain a critical tool in assessing mortgage suitability, analysis of UK residential property data shows they do not reliably indicate exposure to key environmental risks such as flooding and ground instability,” says Colin Bradshaw, CEO at TwentyCi.
“In fact, some of the UK’s most energy-efficient homes are also among the most vulnerable to flooding and subsidence. For lenders, that creates a potential blind spot in portfolio risk. To build truly resilient mortgage books, lenders need to assess energy efficiency alongside a broader range of environmental risk factors.
“As climate pressures intensify, the data underscores the need for a more holistic approach to mortgage underwriting. Relying solely on EPC ratings could leave lenders exposed to hidden risks, particularly within segments of the housing market traditionally considered ‘safe’.”
