Sheffield Winter Garden

The Winter Garden is a centrepiece of Heart of the City, a regeneration programme for central Sheffield costed at £120 million (£130 million according to the architects) that also produced the Peace Gardens and the Millennium Galleries. The scheme was funded by the Millennium Commission, the city council and English Partnerships.

Pringle Richards Sharratt, now Hart McGregor, won the design competition in 1995. Design work began in 1996, with Buro Happold as structural and services engineers and Weddle Landscape Design as landscape consultant. The neighbouring Millennium Galleries were completed in 2001 and the glasshouse in 2002, on a budget of about £5.5 million; according to the architects, 130,000 people visited in its first month.

Queen Elizabeth II and the Duke of Edinburgh formally opened it on 22 May 2003. The building has since collected a string of awards, including a RIBA Award shared with the Millennium Galleries, a Civic Trust Award, a RICS award for design and innovation, the Landscape Institute President's Award and a Green Flag Award. It also played a part in Sheffield's Entente Florale win in 2005.

The glasshouse is 70 metres long and 21 metres high, rising to 22 metres at its peak, enclosing about 1,570 square metres. It is one of the largest glue-laminated timber buildings in the UK. Its frame is formed by twenty-one European larch arches set 3.75 metres apart; Buro Happold describes them as following an inverted catenary, while the architects call them parabolic. The largest timber members are up to 24 metres long and 900 mm deep. Left untreated for its natural durability, the larch weathers to a silvery grey.

The main arches rest on sculpted steel cradles and the intermediate ones on raking timber struts, while the end arches lean outwards to form entrance canopies. Slender purlins and glazing bars carry more than 2,000 square metres of glass. The architects describe it as naked architecture, drawing on Victorian engineering and in particular on the train shed at St Pancras.

The climate is kept frost-free at a minimum of 4 °C, regulated by automated vents and fans, with heat supplied from the city-centre district heating network.

The glasshouse holds more than 2,000 plants from around the world, grown in a temperate atmosphere kept just above freezing. The tall central space was designed so that large specimens could reach their mature height: Norfolk Island pines, eucalyptus and Chusan palms give the planting its framework.

Beneath them, the flower beds are changed five times a year, giving each season a different character. The displays have earned three gold awards from the European Federation of Interior Landscaping Groups.

The Winter Garden stands at the eastern end of the city centre, near the Town Hall, between the Peace Gardens and the Millennium Galleries, with which it forms a continuous route through to Tudor Square. Its street-facing ends also make it a natural short cut.

Half an hour is enough to walk around it, but it pairs easily with the neighbouring galleries and the Peace Gardens. Because the beds are replanted several times a year, it rewards return visits in different seasons.