Rachael Warwick, who oversees three schools in southeast England, has had to sign a new contract to heat and light their buildings at tariffs that she describes as "eye-watering".
The executive head teacher of Ridgeway Education Trust in Oxfordshire calculates that if the schools she runs use the same amount of energy as before, their annual bill will go up from £250,000 to £1.1 million ($290,00 to $1.3 million).
"It's massive... We are looking for £900,000 pounds additional, unbudgeted money," she told AFP, saying that paying this would exhaust financial reserves within a year.
The schools in the trust will do "sensible things" to cut energy use but raising such a large amount would require firing 30 teachers, she added.
Publicly funded schools in England are sounding the alarm as soaring energy prices hit their already tightly constrained budgets. This comes as schools are expanding activities after pandemic curbs.
UK households and businesses are also facing severe financial hits from energy bills that have soared in the post-pandemic era, exacerbated by Russia's war on Ukraine.
A spokesperson for the government's education department told AFP: "We are aware of the inflationary pressures facing schools and know that rising costs will impact schools differently."
The department pointed to a £4-billion rise in funding for schools announced last year and said it was recommending energy deals.
England's commissioner for children, Rachel De Souza, vowed "schools must absolutely not close" in an interview with The Telegraph late Friday.
Forgotten
In the campaign to become the next Conservative party leader and UK prime minister, neither Liz Truss nor her rival Rishi Sunak, made firm commitments to help schools cover huge additional costs.
"I really hope that when we have a new PM, things will be done with the urgency it requires," said Warwick, stressing that while the energy crisis affects all sectors including health, "schools can't be forgotten. It's an essential public service."
She called on the government to set an energy price cap for schools, similar to that for domestic users.
"I think Liz Truss has been quite clear about what her priorities are -- a lot of stuff about tax cuts -- but there hasn't been any mention of bailing out public sector bodies," said John Dickens, editor of the Schools Week newspaper.
"The public sector -- schools and other institutions -- they seem to have been forgotten about a little bit."
Head teachers and unions are urging the government to do more.
"We will be making representations to the new government ministers when they are in post next week to put this at the top of their priority list," said Julian Gravatt, deputy chief executive of the Association of Colleges, which includes institutions teaching children aged 16 to 18.
"We need to do something. It is a national problem and I think we should view it like that," said Paul Gosling, headteacher of Exeter Road Community Primary School in Exmouth, southwest England, who is president of the NAHT headteachers' union.
Deficit
From next month, Gosling's small school of several hundred pupils will have to switch to a new energy contract at current market prices.
He fears that will cost up to £60,000 -- three times more the current sum.
"If the government doesn't step in to help, many schools are predicting that they will be plunged into deficit this year," NAHT general secretary Paul Whiteman said.
Education is a devolved issue, with schools and policy the responsibility of the devolved governments in Scotland, Wales and Northern Ireland.
The UK government in London is in charge in England, where state schools are either funded directly by local authorities or classed as "academies" with greater autonomy on budgeting, a reform introduced by former premier Tony Blair.
While schools are not profit-making businesses, the UK government has not committed to further help with energy bills.
Schools are going to have to "fire staff, stop doing extra-curricular activities, all these things that would have driven a recovery in our schools," said Dickens.
"These things are going to have to be cut just so schools can keep heating and lights on."
Schools have been "cash-starved" since 2010 when Conservative PM David Cameron's government brought in "austerity policies" after the 2008 global financial crash, Dickens said.
Recently, the government has boosted money available but the newspaper editor said this will be "wiped out" by "new unforeseen costs" including energy.
(AFP)
Bob Blackman MP speaks during the event