The UK Green Building Council has claimed that construction firms installing energy efficiency measures through the Energy Company Obligation (ECO) and manufacturers that make products such as solid wall insulation fear more than 10,000 jobs could be lost if ECO is scrapped or scaled back.
They expressed caution after prime minister David Cameron signalled his desire to roll back green levies following the public debate on the cost they add to household energy bills.
The chancellor George Osborne was expected to announce an easing of the taxes which were designed to encourage investment in and production of sustainable energy and efficiency while penalising dirty fossil fuels.
But Paul King, chief executive of the UK Green Building Council, said the government's proposal could lose thousands of jobs.
"The prime minister needs to realise that going after ECO in a bid to cut household energy bills could end up costing 10,000 construction and insulation jobs," said King.
"That will decimate the very industry that is helping people - including some of the most vulnerable in society - reduce their bills in the long-term."
The Association of the Conservation of Energy estimated that up to 33,000 people are employed delivering ECO and the Green Deal.
This should have risen to 60,000 jobs in 2015, according to government's own projections.
Rob Lambe, managing director of Willmott Dixon Energy Services, added: "We have invested heavily in establishing a business to respond to the projected market opportunities of energy efficiency under ECO.
"Over the next year we anticipated employing more than 400 tradesmen installing insulation to solid walled properties.
"But if ECO funding is cut, this work will simply come to a grinding halt and these jobs will be lost, with thousands more at risk in the wider industry."
The government is expected to announce its intentions in the autumn statement in December.