West Exe Technology College opened 18 months ago and is one of five Exeter secondary schools and one primary school which has experienced problems.
Devon County Council and contractor Carillion are still negotiating over the issues raised by the schools, with Carillion undertaking some remedial work in the past year.
But West Exe College was so concerned about the potential impact of overheating this summer it has set aside extra money to pay for work to improve natural and mechanical ventilation in 12 classrooms.
Governor Paul Smith said: “Last summer we had a lot of staff and students off sick because they simply could not stand working in a glass house.
“Things have improved, but they are still not right. It is incredibly difficult to stop overheating in these classrooms because there is no throughput of air.
“We have always had a good attendance record among staff and students, but last summer there was a noticeable increase in sickness.
“This is a brand new school and most of the building is fine, but we have still got these issues.”
Ongoing problems at St Peter’s CE School, which also opened 18 months ago, have led the county council to send researchers from Exeter University back in to analyse conditions.
Heather Morgan, chairman of governors at St Peter’s, held a meeting with the county council on Monday. She said: “We are very grateful for the support from the local education authority and I am very optimistic we will be able to make progress on this.
“We want our school to be healthy. At the moment there are a number of classrooms which are particularly bad, but there is a general problem of ventilation and air quality throughout.
“I think the fact this was a PFI slowed down sorting this out. Everything has to be done in relation to the contract and not what is needed.
“All the time we have had to go through the county council rather than negotiate directly with the contractor.”
The school projects were taken on by Carillion when it took over Mowlem. Carillion is now the main contractor within the special purpose vehicle Modern Schools Exeter, which runs the school.
The company has told the county council the original designs were in line with the Building Bulletin 87 (BB87), the guide for environmental design for schools set down by the Department for Children, Schools and Families. The designs emphasised natural ventilation, but both natural and mechanical ventilation were used.
A Carillion spokesman said: “Carillion and Modern Schools Exeter have been working with each individual Exeter PFI school in order to identify suitable measures which can be implemented in the small number of rooms which have suffered with temperature and ventilation problems.”
A county council spokesman said: “West Exe and St Peter’s are the most affected. There were problems when the schools opened and there are still issues in some classrooms.
“It was West Exe’s decision to spend this money on work which was not covered by the contract with Carillion.
“We are still in discussions with Carillion over whether other additional work in
the schools is part of our contract.”