Best travel organisation: Youth Hostels Association

"Thanks, i'll have an orange juice." I gave this innocuous response when invited to have a drink at the opening ceremony for the Earl's Court youth hostel in London. Little did I know I would come up against a refreshingly direct example of sustainability in tourism. "I'm afraid you can't have one," the hostel manager explained. "Rather than using stuff imported from the tropics, we only serve juices made from British fruit. We've got some lovely organic apple juice from Kent, though." Not many food miles there, then.

The Youth Hostels Association has been at the forefront of environmentally sensitive tourism since its inception 80 years ago. While the typical hosteller has changed dramatically, the YHA's focus on celebrating the great outdoors remains. Many youth hostels intelligently revive existing buildings – such as Idwal Cottage in Snowdonia, which was originally built for the manager of a slate mine but now caters to hikers. At the other end of Wales, Port Eynon in the Gower Peninsula is a former lifeboat station with a shoreline location that the finest hotel would crave.

The YHA has established a string of "Green Beacon" hostels that deploy 21st-century technology to environmental effect – including the former village school in Lockton in the North York Moors, which has everything from solar panels to composting toilets. And the greatest of them all? The monks' quarters adjacent to the ruins of Whitby Abbey, perhaps the only place you will ever stay that boasts original wattle-and-daub features. All yours for £19.95 a night – and so special that the hostel runs tours of the interior for anyone unfortunate enough not to be staying there.

Simon Calder is travel editor of The Independent