Cologne  - Sofas made of recyclable material, garden furniture crafted from local wood and wine glasses from old bottles - manufacturers are falling over each other to bring out products stamped "sustainable."

Only a few months ago it was the preserve of upmarket designer labels to emphasize the ecological soundness of their products, but now it is the turn of the lower-priced makers to slot green products into their range.

"Sustainability has just been hyped out of all proportion," say the organisers of Cologne's renowned imm furniture show. An increasing number of consumers are looking for lifestyle products with natural input although this is not restricted to the objects themselves being made from recyclable materials. The buzzword is systems, namely the process by which a product is generated from start to finish.

This enhanced level of sustainability has already been reached, according to Ioanna Paraskeva who represents the Cologne-based online platform designspotter. com. "It has a lot to do with a feeling of responsibility," she explained. Designers are concerned with the effect of today's products on future generations and in the nitty-gritty of how they are put together. The question being asked these days is "who made this product and where does it come from," said Paraskeva.

Trend expert Eva Barth-Gillhaus from Meerbusch in North Rhine-Westphalia believes the greater attention being paid to sustainability has already changed people's perceptions.

Like Paraskeva she detects a return to traditional values of longevity and durability in the field of eco-products. These days the quality of workmanship is just as important as the use of environmentally-friendly materials and cutting-edge design. Until lately the former was often absent in this segment, in contrast to the new generation of green furniture which is being driven by high-tech and sophisticated forms.

Hand-finished furniture made of massive wood is enjoying a boom too but various materials are now regarded as being sustainable, including plastic. "Over the last ten years plastic was practically under house-arrest, now it's enjoying a renaissance," said Professor Peter Wippermann of Hamburg-based trend observing agency Trendbuero.

This about-face has been made possible by technological advances. Plastic chairs such as Konstantin Grcic's "Myto" cantilever creation are a good example. His chair has no back legs and is supported by its own structure. It was designed on a desktop PC and can be mass-produced using computer-operated machinery. The manufacturing process produces a bare minimum of waste and is therefore kinder to the environment.

For furniture to be genuinely ecological it must be made for a long lifecycle, say the experts. This means designers should opt for timeless forms which will remain attractive to the eye for years on end. Furniture for children must also be flexible enough to adapt to a child's needs as it grows older.

A good example of this philosophy is the "Growing Table," which designer Olaf Schroeder from Stuttgart has created for his own label Pure Position. Both table and chair are suitable for toddlers but can be made gradually taller in increments of 10 centimetres by inserting the extra leg elements available. "This extends the lifecycle of the product by up to eight or ten years," Schroeder says. (dpa)