Schools could be forced to cut teaching staff, increase class sizes and axe school trips because energy bills are expected to rise by 300 per cent, it has been warned.
The energy price cap does not cover schools and businesses, and will rise to £3,549 a year for those on default tariffs in October.
As a result, some schools will have to consider reducing the number of teaching assistants, scrapping building projects and school trips, as well as increasing the size of lessons and introducing restrictions on heating, it is claimed.
Geoff Barton, general secretary of the Association of School and College Leaders (ASCL), told MailOnline: "It is likely that we will see cuts to curriculum options, larger class sizes and reductions in extra-curriculars such as school trips and the number of teaching assistants."
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Rachael Warwick, executive head teacher of the Ridgeway Education Trust, which oversees three schools in south Oxfordshire, said its gas bills were due to rise by 525 per cent next month and its electricity bills by 354 per cent.
The trust currently spends £250,000 on gas and electricity each year, which is set to increase to £1.1m.
She said that the trust had "healthy" reserves of about £1m, but they would be "wiped out" in the next year if the government did not provide further financial support.
She added that the schools would do "sensible things" to cut energy use, but warned that if changes were not made it could lead to redundancies, fewer extra-curricular activities and some subjects being removed.
Speaking to Radio 4's Today programme, Ms Warwick said: "If you fast-forward 18 months... we simply cannot manage ongoing increases of nearly £1m a year for our utilities costs."
Nick Hudson, chief executive of Ormiston Academies Trust, which has 43 academies nationwide, told the programme that energy costs had risen by 250 per cent since March.
He said the trust was expecting an energy bill next year of £14.3m - £9.2m more than in 2021/22.
The National Association of Head Teachers (NAHT) said many schools were anticipating that they would go into deficit this year unless the government increased its help for schools.
Robert Halfon, chairman of the Commons education committee, said the government should introduce three different subsidised tariffs - for struggling households, essential services, such as schools, and small businesses.
A Department for Education spokesman said: "To support schools we are increasing core funding by £4bn this year alone."
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