Set in rolling hills overlooking the Tywi Valley in Carmarthenshire, the Great Glasshouse forms the centrepiece of the 230-hectare National Botanic Garden of Wales. The largest single-span glasshouse in the world, containing more than a thousand Mediterranean plant species, it reinvents the glasshouse for the twenty-first century, offering a model for sustainable development.
Elliptical in plan the building swells from the ground like a glassy hillock, echoing the undulations of the surrounding landscape. The aluminium glazing system and its tubular-steel supporting structure are designed to minimise materials and maximise light transmission. The toroidal roof measures 99 by 55 metres, and rests on twenty-four arches, which spring from a concrete ring beam and rise to 15 metres at the apex of the dome. Because the roof curves in two directions, only the central arches rise perpendicular to the base, the outer arches leaning inwards at progressively steep angles. The building's concrete substructure is banked to the north to provide protection from cold northerly winds and is concealed by a covering of turf so that the three entrances appear to be cut discreetly into the hillside. Within this base are a public concourse, a café, educational spaces and service installations.
To optimise energy usage, conditions inside and outside are monitored by a computer-controlled system. This adjusts the supply of heat and opens glazing panels in the roof to achieve desired levels of temperature, humidity and air movement. The principal heat source is a biomass boiler, located in the park's Energy Centre, which burns timber trimmings. This method is remarkably clean when compared with fossil fuels, and because the plants absorb as much carbon dioxide during their lifetime as they release during combustion, the carbon cycle is broadly neutral. Rainwater collected from the roof supplies 'grey water' for irrigation and flushing lavatories while waste from the lavatories is treated in reed beds before release into a watercourse.
Sketches + Drawings
“Glasshouses have captured the imagination of generations of architects and engineers, from Joseph Paxton onwards. Here, the challenge was to find a form that would not only be structurally economical – that would do ‘the most with least’ – but one that would also fit seamlessly into the natural landscape.”
Facts + Figures
- Appointment: 1995
- Completion: 2000
- Area: 5,800m²
- Capacity: 40
- Client: National Botanic Garden of Wales
- Structural Engineer: Anthony Hunt Associates
- Quantity Surveyor: Symonds Ltd
- M+E Engineer: Max Fordham & Partners
- Additional Consultants: Gustafson Porter, Colvin and Moggridge
- The Dewy-Prys Thomas Prize - Great Glass House,
- D&AD Silver Award for Environmental Design & Architecture
- H & V News Awards – Environmental Initiative of the Year Awarded to the
- Civic Trust Award
- The 2000 Leisure Property Awards
- The Concrete Society Building Award (for outstanding merit in the use of concrete)
- RICS (Royal Institute of Chartered Surveyors) Building Efficiency Award for
- Architecture in Wales Eisteddfod - Winner of Gold Medal in Architecture ( Alwyn Lloyd Memorial Medal)
- RIBA Architecture Award
- Structural Steel Awards
- BIAT Open Award for Technical Excellence
The building's internal environment and the weather outside are monitored by a computer-controlled system, which adjusts the supply of heat and opens 4 x1.5 m glazing panels in the roof to achieve desired levels of temperature, humidity and air movement.
Related Press Release: