Nearly 900,000 families relying on heat networks face an “impending energy crisis” as bills surge by up to 700%, warns a report by the think tank Social Market Foundation (SMF).

These networks, which supply energy from a shared source to one in 25 houses, are prevalent in social housing, where one in 12 households is connected.

The analysis reveals that the government’s estimate of 480,000 households served by heat networks is outdated, with the actual number potentially reaching 900,000.

Key challenges identified include poor energy efficiency, high maintenance costs, a lack of metering leading to excessive energy use and costs and inadequate regulatory protection.

The ongoing energy crisis has exacerbated these issues, as heat network consumers were not eligible for the government’s Energy Price Guarantee.

As fixed-rate energy deals expire, households are now facing bills doubling or increasing by 500-700%, the SMF has estimated.

The report recommends improving the bill support scheme, accelerating the transition to metered networks, regulating heat networks by April 2024 and dismantling inefficient networks.