The client brief required an iconic building inspired by nature and built, as far as practicable, with sustainable building materials. The roof has therefore been developed in timber, obtained from managed, sustainable sources (FSC certified). The use of concrete has been minimised due to the amount of embodied energy in the production of the cement.
The basic roof geometry is derived from a geometric pattern found in nature. In most plant species new growth propagates from central regions called shoot apical meristems. The meristems create primordia which develop into various plant organs (seeds, leaves, petals etc.) and collections of primordia form into patterns which are retained as the plant develops. The study of these patterns is known as phyllotaxis, in the case of the Core roof, the particular pattern is based on spiral phyllotaxis and is commonly seen in nature, for instance, the seed head of a sunflower or a pine cone.
The roof is symbolic of a tree canopy, with the columns being representative of the plant stem or trunk and the foundations of the root system. Each node within the roof structure represents the mathematically idealised position of a seed on a seed head, superimposed on a toroidal form generated by rotating a 26m radius curve around the centre of the structure. The roof covers a plan area of approximately 2360 m2 constructed with an interlocking series of beams in glued laminated timber. Each beam spans two roof bays, with individual beams working primarily in bending carrying the perpendicular span at its mid point. The roof as a whole utilises some shell action and consequently introduces a significant degree of axial load in the individual components. Overall spans of the roof, from the central ring beam to the perimeter, vary from approx. 14m to 28m.
Foundations are on the softer grade III & IV granites or fill material won from elsewhere on the site during the Phase 1 works. Vertical loads are carried on simple pads or strip footings, perimeter props that carry significant horizontal reactions require ground anchors to resist sliding.
Completion 2006
Cost: £35m total phase 4 works, including £12m for The Core building.
Architects: Grimshaw
Contractors: McAlpine Joint Venture