The Serpentine Gallery Pavilion, West London

WHAT: This year鈥檚 temporary pavilion is a walled enclosure with a floating roof resembling an air-balloon.

WHERE: The Serpentine Gallery in Kensington Gardens, West London.

WHO: The pavilion was designed by celebrity architect Rem Koolhaas and structural engineer Cecil Balmond of Arup. QS: Davis Langdon, contractor: Bovis Lend Lease.

HOW: The roof is kept aloft by helium. It can be inflated and deflated to accommodate whatever activity the pavilion is hosting. The 鈥渂alloon鈥 is made of semi-clear PVC coated polyester.

HOW MUCH: 拢750,000

WHY: The pavilion will host a programme of talks, films and lectures from July 6 to October 5. It features a caf茅 and facilities for broadcasting televised events.

HOW BIG: Overall site area: 650m2, pavilion footprint: 346m2, maximum height of inflated membrane: 24m

DESIGNER鈥橲 VIEW: 鈥淭hese pavilions have evolved with various structural typologies and materials, provoking debate on architecture. This year the exploration continues not only with typology and material but with the very definition of pavilion鈥 鈥 Cecil Balmond, Arup vice chairman