World’s first fully transparent Sky Pool spanning two buildings ten floors up opens in London.
The world’s first transparent Sky Pool, spanning 15 metres at high-level between two residential buildings has opened at EcoWorld Ballymore’s prestigious Embassy Gardens development in Nine Elms, south London. Embassy Gardens residents can enjoy a swim like no other, with a panorama of the UK capital viewable through every surface of the pool.
Sky Pool has been designed by London-based HAL Architects and award-winning structural engineering consultant Eckersley O’Callaghan [EOC] and fabricated in acrylic by Reynolds Polymer Technology in Colorado.
Sky Pool has been six years in the making. Initially conceived as a swimmable aqueduct, the design process evolved to make the most of unparalleled views across London. Project client Sean Mulryan, Chairman and chief executive of Ballymore insisted that the pool had to be fully transparent.
Initial designs explored the use of glass, though it quickly became apparent that the necessary joints and thicknesses of glass to retain strength and stability would undermine the transparent vision. Taking inspiration from some of the world’s most impressive giant aquaria, EOC engineered an acrylic structure, and working with HAL and Reynolds, refined the design to create the striking clarity of the final structure.
Hal Currey, Director of HAL Architects explains: “The intention was to keep the design simple. It had to appear as transparent and effortless as possible. Acrylic offered aesthetic benefits as it appears colourless, its refractive index would give the impression of it blending with the water and joints in the structure would not be visible. We faced a combination of challenges: the transparency, the acrylic and spanning the two buildings.”
The undertaking was considerable – Reynolds had to build an outdoor facility to accommodate the size and complexity of the project. The side walls of the pool are 180mm thick and 3m deep. Its bottom slab is 360mm thick and the whole pool weighs 50-tonnes. Because of its size, Sky Pool has been constructed in separate sections with transparent joints cleverly designed to maximise the bond area and avoid areas of high stress.
The 15-metre acrylic section of the pool is slotted into specially designed housings on stainless steel ‘tubs’ 5m long on the building roofs at either end. These carefully conceal Sky Pool’s water filtration and plant equipment. Two 38mm diameter high-strength cables tensioned between the tubs act to bring the tubs and acrylic together to create a stable 25m long unit. To ensure the two buildings can move independently of one another, Sky Pool is supported at either end on bridge bearings, so that the two buildings are not rigidly connected.
Sky Pool has been hydrostatically tested both at Reynold’s facility and numerous times on site after it was lifted into in September 2020, following an epic journey to Nine Elms which included a 1000 mile road journey from Colorado to Galveston Texas, trans-Atlantic ferry to Antwerp and Thames boat from the Port of Tilbury.
The delicate lifting operation was carried out with a 500-tonne mobile crane situated on the northwest side of the buildings in just 2 hours. Tolerances for the lift were extremely tight with less than 25mm of adjustment allowed.
Eckersley O’Callaghan Founding Director Brian Eckersley said:
“We are really proud of what we’ve achieved with Sky Pool. From an initial concept which people thought couldn’t be done, to seeing it designed, fabricated, installed, and now opened is a fantastic engineering feat and we hope it will act as an inspiration to all.”
Co-Founding Director James O’Callaghan said:
“The Sky Pool is a true testament of our commitment to innovation and pushing the boundaries of what is possible in engineering. What has been achieved by the whole team is nothing short of incredible. It’s a structure of remarkable transparency and we are looking forward to seeing people’s reactions as they swim across.”
Sky Pool – Credits
Client: EcoWorld Ballymore
HAL are architects based in London. HAL’s residential and urban regeneration projects are centred on the discovery and exploration of a site’s heritage to generate an approach to place-making and to the architecture of its new buildings and spaces. If the design lives up to the story, then the new place and its buildings are better for it.
The practice, founded in 2015, is led by Hal Currey, who spent his formative years at the Richard Rogers Partnership, before establishing FLACQ Architects. FLACQ merged with Arup Associates in 2010.
Recent projects include large-scale residential schemes The Modern, Embassy Gardens for EcoWorld Ballymore in Nine Elms, South London and marketing led schemes at Goodluck Hope, City Island and the Brentford Project (all for Ballymore); East Ridge in Walthamstow for Provident Capital and Rubric in Whetstone for GM Developments. The Sky Pool, the world’s first fully transparent swimming pool built ten stories up between two residential buildings in Embassy Gardens, designed by HAL and engineered by Eckersley O’Callaghan for EcoWorld Ballymore, opened in June 2021.
Engineer: Eckersley O’Callaghan
Eckersley O’Callaghan has established an international reputation for its creative and innovative yet rigorous, approach to engineering structures. Its engagement with architecture and industry underpins its pioneering use of materials to realise projects of exceptional quality, efficiency, and elegance.
Since forming in 2004, Eckersley O’Callaghan has grown to over 110 strong with offices in London, Manchester, New York, San Francisco, Los Angeles, Paris, Hong Kong, Shanghai and Sydney. EOC works on a range of extraordinary building projects in the UK and across the world, from conventional structures in timber, steel and concrete, through facades and bespoke glass structures to specialist marine design.
It is well known for collaborating with Apple on all of their flagship projects around the world. EOC’s innovative use of glass, acrylic and carbon fibre reinforced polymers, as well as sensitive adaptations of historic buildings and sustainable design have become signature features of the brand.
Fabrication/Engineering: Reynolds Polymer Technology