Teachers in Wales avoid giving lessons on reducing carbon footprints because of the appalling state of their school buildings, an environmental specialist has said.
Former primary teacher Julie Bromilow, who is now an education officer at the Centre for Alternative Technology near Machynlleth in Powys, said staff felt so let down by the eco-unfriendliness of their classrooms that they did not feel able to discuss such issues with pupils.
"They feel they can't discuss it because their buildings are so inefficient," she said.
But staff must change their attitudes to teaching sustainability so that young people learn the practical everyday steps they can take to halt climate change, she said.
According to Assembly government figures, local authorities in Wales spend less on school maintenance and upkeep than any other council service.
Ms Bromilow said many "misconceptions" about environmental issues were being taught. She challenged staff to make teaching practical measures, such as draught-proofing, more "sexy" to pupils, instead of planning lessons around "more exciting" alternative forms of energy, such as wind farms, which often generate a lot of interest.
She is also sceptical about the merits of newly built eco-schools because attending these does not teach pupils the simple steps they can take to help save the planet.
Often, she said, schools' sustainability lessons do not go far enough.
"All children hear about is switching lights off and recycling in school, but they really don't have much effect," she said. "Recycling, for example, is actually very energy intensive. Consuming less is the only real way forward."
Part of the battle, she said, is to convince teachers of the importance of education for sustainable development and global citizenship in the school curriculum.
"We've had environmental education for decades, but it hasn't really made a big impact because it has been taught separately," she said. "At our centre we have six education officers - all trained teachers - and we know what it's like to be bombarded with stuff and just think this is the next big thing. But it is so important."
Sustainable development and global citizenship are taught as part of personal and social education in Wales's schools. There is no set curriculum, but schools are expected to weave it through different subjects.
But Ms Bromilow said: "Schools tend to forget about environmental issues. It is still seen as a dumbed-down science and a bit fluffy. But we are trying to change that."
The centre holds training sessions for teachers, giving them a rigorous scientific background to the problems of climate change.
"They are not expected to teach pupils in that much depth - we hardly speak about climate change with students," she said. "However, it is important for teachers to have an understanding of where all this is coming from. Some teachers are very surprised that the situation is as serious as it is."
Food, transport and buildings are three of the biggest concerns for the future, she said.
"Food is not usually seen in a sustainable light in schools," she said. "It's all about healthy eating in schools, but if freshly cooked and locally produced food is also thrown in then healthy eating schemes can suddenly become brilliant."
Teachers could even have a positive impact on their school building by buying monitoring equipment so pupils could measure how much energy is being used, she added.