Most social homes may be technically capable of decarbonisation, but the difficult cases matter because they absorb disproportionate time, money and professional attention. The challenge is concentrated in older, heritage-sensitive or complex properties where standard retrofit pathways do not fit cleanly.
Cost is only one barrier. Planning restrictions, conservation requirements, resident disruption, contractor availability and uncertainty over acceptable solutions can all slow progress.
This creates a risk of two-tier improvement. Easier homes move forward, while harder stock is delayed until later. But delaying the hardest homes can make the eventual programme more expensive and politically exposed.
Housing providers need a more granular approach. Not every home requires the same pathway. Some assets may suit fabric upgrades first, others heating-system changes, and others a phased plan tied to wider estate renewal.
For policymakers, the message is that funding alone is not enough. Planning guidance, technical standards and supply-chain capacity must support delivery.
Hard-to-decarbonise stock should not be treated as an exception at the end of the programme. It should be identified early, because it is where the real delivery risk sits.