Vast numbers of windows and many roofs need replacing in East Riding schools to cut rising carbon emissions bills.
A review which examined the state of repair of 145 schools in the county warned secondary and special schools were in need of “substantial” investment, with some “reaching crisis point”.
A number had flat roofs and many were constantly leaking, while “significant” numbers still has single pane windows which leak heat.
A review panel, made up of East Riding councillors, was set up in the wake of the Government axing the Building Schools for the Future programme, which saw £380m invested into schools in Hull, and which the East Riding missed out on.
There is now concern that after years of pupils from Hull seeking places in East Riding schools, the trend could be reversed.
East Riding Council is already spending £237,000 on allowances for carbon emissions, with the figure set to rise further. Schools are responsible for over half of the council’s emissions.
But the panel was unable to find cast-iron sources of funding to meet the cost of improvements - £13m just for upgrading roofs, windows, doors and cladding.
One possibility was using capital receipts from the sale of surplus school land - but that could be problematic with Sport England likely to object.
In its conclusion the panel said they couldn’t find a link between poor condition of buildings and pupils’ attainment, although better facilities were thought to be better for morale.
It said the impact of new academies in Hull on pupil numbers in the East Riding “is still unknown but must be carefully monitored.”
It added: “Schools face an onerous carbon emission reduction target of 42 per cent by 2020 and will face financial penalties if targets are not met.
“The Panel was concerned that as the condition of school buildings continues to deteriorate, it will only impact further, with schools becoming even less energy efficient.”