Winner: Saint Bede's Catholic High, Lytham St Annes, Lancashire
This category attracted one of the highest numbers of entries, with schools across the UK eager to promote their schemes for conserving energy and recycling.
But Saint Bede's went much, much further. As well as installing a ground-source heat pump and no fewer than 99 solar panels, it transformed an energy-inefficient 1960s block into a model of eco-refurbishment.
The school has redeveloped its grounds into an educational resource to teach pupils about climate, agriculture, biodiversity, creating allotments, planting an orchard and introducing composting bins and water butts. This summer it will even begin to construct a geodesic "Solardome", on which it is working in partnership with the team behind the Eden Project.
Its work has, rightly, attracted other awards, and been praised by figures including Prime Minister David Cameron and Ed Miliband, former energy and climate change secretary.
Judges' verdict: This school had it all - lots of innovative renewable energy kit, a fantastic organic garden and a wide range of green events. The judges liked the fact that the approach fed into lots of the school's activities, and was embedded in everything it did. They also praised the way the eco work rippled beyond the school to involve parents and families, and the colossal overall reduction in CO2 it was achieving as a result.
The King Edward VI School, Morpeth, Northumberland
Students led much of the work here on sustainability, with a typical example being a debate they launched in the UK Youth Parliament on green issues.