CASE STUDY | TOTTENHAM HOTSPUR STADIUM To cope with the huge variations in domestic hot water demand leading up to, and during, a match, the calorifiers are heated by low temperature hot water (LTHW) with electric backup. Owen quotes a domestic water demand figure of 4L.s-1 at three hours before kick-off, rising to 11L.s-1 20 minutes before kick-off. This pales into insignificance, however, when compared with the 55L.s-1 to satisfy the half-time rush. In contrast to the hospitality floors, main concourses on level one and level five are classed as outside spaces, because they incorporate openings to the spectator THE STADIUM STANDS, LEVEL BY LEVEL Starting at the basement, the levels in the North, East and West stands are: Basement: car park Level 0: pitch level, where the changing rooms and match-day facilities are located Level 1: main concourse, where the public enters, It is also where many of the bars and food outlets are located Levels 2, 3 and 4: hospitality floors Level 5: high-level concourse Levels 6 and 7: mechanical plant spaces Levels 8 and 9: additional hospitality, including the level nine Sky Lounges on top of the East and West stands, joined by a glass bridge incorporated into the roof structure to give spectators panoramic views of the pitch. seating pitch side and feature perforated sections of the faade on the exterior. As a result, piped services in these areas incorporate trace heating. The area beneath the South Stand is also classed as an external space, although Owen says the large area of glazing means it will remain comfortable, even in winter. Pitch perfect The South Stand accommodates the pitch pocket a basement recess into which the grass pitch can be retracted in three sections, each weighing more than 3,000 tonnes, by 68 electric motors in 25 minutes. Being able to roll the pitch into a purpose-designed repository is fundamental to maximising the buildings functionality. As well as allowing American football to be played there, it enables the stadium bowl to be easily converted into a venue for concerts and other events. Environmental conditions are critical to ensure the grass on the pitch is maintained in perfect health while it is stored. Lighting that mimics sunlight and irrigation systems keep it green and watered. The grass has to be kept healthy, but they dont want it to grow too much, because it cannot be cut when stored in the pocket, says Owen. The key is to keep the temperature in the pitch pocket cool while blowing air to agitate the grass. In agitation mode, we ramp up the fan speed to blast air out of nozzles so that it ruffles the grass, adds Owen. The pitch pocket has two bespoke environmental systems: one humidifies and dehumidifies the space; the other provides heat and cooling. Owen says the cooling load is massive, and when the pitch is in storage, energy is diverted from stadium systems to serve the pitch-pocket environmental plant. Its a trade-off, he explains. Pre-event, while the stadium is still in The stadium incorporates a huge amount of IT, from security to pitch lighting 36 November 2019 www.cibsejournal.com CIBSE Nov19 pp34-38 Tottenham ground.indd 36 25/10/2019 14:48