Staff and pupils at schools across Northern Ireland have been told to "wear more clothes" if it is cold in order to cut heating bills.
Schools have been told by the Education Authority (EA) that increasing costs will affect school energy bills and to reduce heating and lighting "wherever possible".
The authority has said that school gas and electricity bills are set to rise by about £8m by March 2027.
But principals have told BBC News NI it is not straightforward to cut heating costs, with one describing her school's energy bills as "ferocious".
Rising energy costs are already affecting households across Northern Ireland.
The impact of the US-Israel war with Iran is one of the factors behind the increase.
The letter from the EA to head teachers said that "recent geopolitical events are expected to have a substantial impact on energy costs... during the 2026/27 financial year".
It said that total school gas bills were expected to go up by 60% from £10.7m to £17m by March 2027.
Meanwhile, total school electricity bills are expected to rise from £23.8m to £25.1m in the same time period.
"Given the scale of the anticipated cost increases, we are asking all schools to review their energy usage and identify opportunities to reduce consumption wherever possible," the EA said.
Among the measures suggested to schools are cutting heating use by an hour a day and switching off classroom lights to use natural daylight instead.
Staff and pupils have also been advised to "wear more clothes" rather than turn the heating thermostat up if it is cold.
Brian Guthrie, principal of Ebrington Primary School in Londonderry said asking children to sit in a class wearing extra clothes is "ridiculous".
"I'm not going be asking children and staff to put coats and hats on during the winter time.
"We will be running the heat as we need it but we do look at all other energy saving costs as we can," he told BBC Radio Foyle's North West Today programme.
Guthrie said his school building is around ten years old and is, at present "very energy efficient".
The installation of 100 solar panels last year, he added, should "have paid itself back" over the next five years.
Children need to be taught in "an ambient classroom", he said. Adding the EA should "look at other ways of saving in schools".
Meanwhile, Emma Quinn from Rathcoole Primary told BBC Good Morning Ulster that the "lack of maintenance" has an impact on schools, adding that pupils have a right to come into a warm school after being outside.
"Putting this pressure onto us at the minute is ridiculous, when we are eco schools, we are doing all of these, we are turning off lights, but yet this lands in on our doorstep.
"We're suddenly expected to jump and to fix a problem that is so systemic, it's just not good enough."
Extracted and lightly reformatted for readability. · Source: en