And these figures only cover the financial costs. Who can put a figure on the cost of the disruption to children's education, the destruction of pupils' and teachers' work or the heartache caused by each of these incidents?
Spurred on by the devastating effect of arson in schools, agencies in Nottingham - the city council, the fire and rescue service and the police - joined with the Arson Prevention Bureau to pilot a scheme to tackle the problem. Around 96 per cent of cautions for arson are issued to youths between the ages of 10 and 19 - but the culprits are rarely aware of the consequences of their actions.
Participating schools have been provided with a curriculum pack, designed by consultants dbda - specialists in this kin of education material - to raise awareness among pupils of the consequences of arson.
The project begins with a specially commissioned theatre in education performance, using young actors to demonstrate the damage that arson can do. The performance is followed by a workshop, picking up themes raised in the play and developing them in a way that is relevant to the children's lives.
Next, schools can draw on the education materials - there are separate sets for key stages 2 and 3 - to build awareness-raising messages into lessons ranging from English and maths, through science and citizenship to art and drama. Supporting information, data and photocopiable resource sheets make the materials as classroom-ready as possible.
The scheme is now being evaluated and organisers hope the project can be offered to other local education authorities.
Larry Stokes is an underwriting manager at school insurer Zurich Municipal, which funded the Nottingham scheme. He also chairs the Arson Prevention Bureau's schools working group