Dave Dobbin - the technology teacher, mind you, not the musician - has earned a reputation among his students as a bit of an inventor.
Seven years ago he walked into his classroom and switched off all the lights, which were mostly on - as was the heater.
It was on for 24 hours a day, by accident.
Dave took a look at his school's power bill and found it was rather large - 450,000 kilowatt hours and $120,000 per annum.
