The Government has attempted to boost its environmental credentials by saying plans to rebuild all secondary schools will produce a new breed of "sustainable schools".
But schools can pass the "green" tests needed to secure funding from the Department for Education and Skills without addressing their energy output.
Roderic Bunn, who was commissioned by the department to investigate early examples of sustainable schools, said environmental assessments were failing to reduce schools' energy use.
"Electricity consumption is going through the roof, even in the newest schools," he said. "The tragedy is that it is possible to get a high environmental rating without fulfilling any requirements relating to CO2 emissions, and they are the biggest problem."
Schools are assessed at the design stage on green issues, including building materials, water usage and whether they encourage pupils to cycle to school.
The DfES asked the Building Research Establishment, a charitable trust that advises on building methods, to draw up test areas for new schools, known as the Breeam tests (see box, right). Of these, one is devoted to energy consumption. However, it is possible to achieve the highest ratings without scoring any points in this section - as long as the design does well in other parts of the assessment.
"It is relatively easy to get the top two ratings without ticking any of the CO2 reduction boxes," said Mr Bunn. "If you have an excellent rating you will have dealt with a range of issues but not necessarily your carbon footprint."
New schools planned under the pound;45billion Building Schools for the Future programme must achieve one of the top two environmental ratings to receive funding.
But assessments are carried out while the buildings are still being designed. There is no follow-up to ensure environmental standards remain high. Mr Bunn said: "The test is an aspiration. Buildings do not lose their ratings no matter how they actually perform." Early examples of supposedly green and sustainable schools have not fared well. In a DfES book of case studies, schools were found to be consuming far higher energy levels than had been predicted.
The Academy of St Francis of Assisi in Liverpool produced almost five times more CO2 in its first six months than was forecast at the tender stage.
Oakgrove secondary in Milton Keynes has achieved some of the lowest levels of energy consumption of any school in England, yet still produces more than double the amount of CO2 predicted.
Anna Surgenor, schools manager at the Building Research Establishment, said the assessmentscovered a wide range of environmental areas, not just carbon use.
"Carbon is a key factor but we do not want to forget about the other critical issues such as pollution and water," she said. "Carbon can be minimised through addressing transport emissions and introducing good daylight to the building design. The Breeam schools benchmarks are higher than current industry best practice."
A spokesman for the DfES said schools could not get high ratings without addressing energy consumption. "A school design that simply meets statutory minimum standards for energy and water efficiency will not get a high rating," he said. "Energy use in school buildings has already been slashed by 40 per cent over the last five years thanks to stricter statutory regulations."
Blue turned green, page 28
Switch those computers off
All new school buildings have to score at least a "very good" rating under Breeam - the Building Research Establishment Environmental Assessment Method.
Breeam rates school design in eight areas: building management, health and well-being, energy, transport, water, material and waste, land use and ecology, and pollution.
According to Roderic Bunn, who evaluated the success of sustainable schools for the DfES, designs need to be kept simple if energy use is to be minimised.
Simple controls for lighting, heating and cooling need to be installed so teachers can easily make adjustments, he says. More effective metering of energy use in different parts of the school buildings will help schools to monitor and reduce consumption.
A school in Stockport has saved pound;16,000 a year by turning off its computers and photocopiers when they are not in use. Hazel Grove high school was paying more than pound;100,000 annually in energy and water bills but, since being assessed by environmental experts, has introduced measures, including turning off computers and putting recycling bins in all classrooms. It has also installed a new system in the boys' toilets to save water - automatic flushing is switched off overnight and at weekends when not in use.