PAPER PALACE.

The Japanese pavilion is the biggest paper structure ever built, and one of the boldest attempts to meet the Expo organizers' aims of generating sustainable, humane construction by using advanced technology.

Shigeru Ban and the organizers of the Japanese pavilion have taken the Expo theme of Humankind-Nature-Technology more seriously than most. A very large proportion of the building will be recyclable when the show is struck.

Ban has made a name as a builder in paper, perhaps most notably with his church at Kobe with its structural walls of cardboard tubes, erected very quickly and economically after the earthquake (AR September 1996). At Hanover, the structure is a lattice of comparatively thin (120mm diameter) cardboard tubes, lashed together with white rope at their nodes (a detail wonderfully evocative of Japanese tradition). The largest cardboard structure ever made, the pavilion is 72m long by 35m wide, with a maximum height of 15.5m. Fundamentally rectangular in plan, three domes are fused together to form a generous and lofty space.

Construction is ingeniously innovative, worked out with advice from Frei Otto, and Buro Happold as consultants. The whole basketwork shell was constructed flat, and then gradually jacked into shape over about two weeks in early February. Tubes in the shell are 20m long and weigh 100 kilos each; they can be spigoted together, in some cases to achieve a total length of 68m. Stiffening is provided by thin ladder-like timber trusses, stayed with wires, arcing across the width of the plan. Loads are transmitted down to foundations made of mass sand enclosed above ground within scaffolding boards supported by steel frames. Sand is used because, unlike concrete, it is recyclable, and so of course are the steel, the timber and the tubes -- the tubes made of recycled German paper, now destined to be recycled again (perhaps as cardboard files).

Covering the roof is a specially developed waterproof and fireproof translucent paper (recyclable of course) which is reinforced by being bonded to an inner transparent pvc membrane. The ends of the dome are closed with the same material, carried on diagonal grids of cardboard stiffened with timber and connected by tubular steel nodes.

You enter at the east end, one storey up (having walked up steps to a little porch carried on cardboard columns). You pass the offices (made of standard reusable transport containers), and come to the top of Ban's ramp, which leads down through the space to ground level at the other end. From the top of the ramp, you should be able to appreciate the big volume, full of light and patterned by the diagonal Japanese grid. But all is disastrously compromised. The exhibition designer has chosen to insert a horizontal white fabric plane which in effect cuts the volume almost in half.

Only in part of the plan is the plane omitted and only there can Ban's space be partly appreciated. The white plane is all the more bizarre in that it seems to serve no function. Five 'islands', tepee-like structures housing exhibitions like 'Reducing [CO.sub.2] emissions' and 'Nature's wisdom', are the main objects in the space, and their pointed tops poke through the horizontal white sheets. The islands seem at first to be very big examples of Japanese origami, but rather than being made of folded paper, they are of ordinary building board. The exhibition designers' only positive gesture seems to be the 'Terra dome', an 8m green sphere of artificial plants on the landing halfway up Ban's ramp.

Apart from this, it is difficult to avoid the impression that they were trying to subvert the architect's intentions: a state of affairs clear in many of the other pavilions, but particularly sad here, where the shell is so elegant, appropriate and innovative.