British Gas is to cut 500 jobs as part of a company-wide efficiency programme.
The energy firm said the changes were necessary in order to stay competitive in a fast-changing market.
The jobs will go in its loft and cavity floor insulation business, affecting staff in Leeds, Oxford and Leicester, according to Press Association reports.
Mark Hodges, British Gas chief executive for energy supply and services, said the company was well-positioned to grow but had to make sure its costs allowed it to stay competitive for consumers.
“I recognise that this will be difficult news for the employees who may be affected," he said.
"However I believe today’s announcement is in the best long-term interests of the business.
"Our priority is to support all those potentially impacted, and to ensure a fair and transparent consultation process.”
British Gas owner Centrica last July revealed plans to cut 6,000 jobs.
It planned to create 2,000 new roles elsewhere leading to a net loss of 4,000.
Centrica will reveal preliminary full-year results on 18 February.
Trade union GMB described the cuts in the loft and cavity wall division as a "real sickener".
"At the end of last year we went through a reorganisation which we were told was to make that business competitive and everyone thought that was behind us," GMB national secretary Brian Strutton said.
"But it seems while we were doing that the company was hatching secret plans to shut the whole operation down.
"Staff will feel gutted and we will think twice about believing anything the company says now."