Eight out of 10 “green” schools - which enjoy an abundance of natural light and ample ventilation - significantly outperform more traditional schools with similar socio-economic features, Professor Brian Edwards of Heriot-Watt University told the conference, which was organised by the Scottish Executive.

Academic results can improve by around 5 per cent and teachers and pupils are happier in their work. Absence rates fall sharply.

Professor Edwards’s startling conclusions about the effects of intelligently built schools on attainment came as the Educational Institute of Scotland in Glasgow claimed many secondary members were suffering in sweltering new schools, built under the public private partnership (PPP) initiative.

Cathy Jamieson, Education Minister, hailed the replacement of 300 schools as a “once in a generation opportunity” but Professor Edwards believes it may already be too late to encompass vital green factors in PPP programmes. “We need to take stock pretty quickly in terms of what is going on with the investment in schools,” he said.

His remarks echo concerns of other Scottish academics that some of the PPP secondaries in Glasgow suffer from inadequate ventilation, student traffic jams and little social space. A wood-burning heating system at Ardnamurchan High in Highland was rejected by PPP financiers because it was an untried and potentially expensive, despite its eco-attraction.

Professor Edwards’s study of schools, particularly in Hampshire, which meet green criteria shows clear links between design and attainment, based on standardised tests and other publicly available statistics. The schools, built between 1984 and 1996, cost 12 per cent more than average but are proving their worth.

Results among primary children are especially striking because they are largely confined to the one space during the school day.

Professor Edwards believes controlled light is crucial, although Government advice south of the border emphasises proper ventilation. High levels of carbon dioxide can make children drowsy.

“Research in America suggests that the more light you put into schools, the better pupils learn, particularly where the light changes a lot so that you have sunlight and cloud. It’s stimulating,” Professor Edwards said.

But he added: “If you have too much light you get glare, computer screens can be affected and buildings can get too hot. What you have to do is design well for light and that is quite difficult.”

Teachers in schools that were built with natural materials displayed less stress, pupils were more relaxed and less intimidated, and parents found the environment more welcoming.