CASE STUDY ROYAL ARTILLERY BARRACKS
Detailed design stage BIM workflow
the natural ventilation system would work under Games conditions. The modelling was based on a peak external air temperature of 29°C. Modelling showed that the dry bulb temperature at the firing line was approximately equal to the external temperature. It also showed the temperature in the seating zone would be between 30-31°C dry bulb. The comfort of the spectators was helped by the building’s inner lining, which reduced the radiant effect of the buildings’ outer skin. ‘It makes a 1 or 2 degree difference,’ says Higgins. In addition to air temperatures, Mott
DRAINAGE
All drainage is recyclable PVC, including manholes and soakaway crates, no concrete is used. The buildings are not connected to the local drainage infrastructure, which eliminated the needed to dig long connection trenches. Instead numerous soakaways are buried in the surrounding playing field. ‘There is a lot of attenuation on the site because the ranges are such a big area,’ says James Middling, associate director at Mott MacDonald. The drainage is set to be exhumed and reused or recycled.
42 CIBSE Journal November 2012
MacDonald also modelled the air velocity inside the venues. The only specified design criteria was that the air speed had to be maintained below 0.2m/s for when shooters were firing air pistols and air rifles on the 10m range. There was no maximum air velocity criterion for the 50m and 25m ranges. A study was undertaken to demonstrate conditions at the firing line for average and peak wind conditions using 2005 CIBSE Design Summer Year Weather Data for the most frequent occurring wind directions and corresponding wind speeds during the event’s opening hours. ‘The modeling showed that we couldn’t naturally ventilate the combined range when it was being used for 10m air pistol and rifle shooting because the stack ventilation will fluctuate, causing excessive air movement if the wind
is gusty,’ explains Middling. To keep air velocities in the combined 50m/10m range within acceptable limits, the design of the range was tweaked so that when used in the 10m mode, it could be isolated from outside using a sliding partition. ‘To achieve the level of control required we had to close the building to the outside and use a mechanical ventilation system,’ explains Leon Higgins. The simple mechanical ventilation system developed for the 10m range uses axial fans mounted behind some of the low-level protrusions. These pull air through the structure and into the fabric plenum and the void beneath the seating. Inside the venue, the warmed air will rise upwards to exit through the rooftop protrusions. Interestingly, mechanical ventilation was not deemed to be necessary for the Finals range. ‘The Finals range was such a huge volume that we didn’t need to mechanically ventilate during the 10m finals, the event only lasted for about 45 minutes,’ says Higgins. BIM modelling was also used to show
how the venue could be built. The structure’s rock music pedigree meant that the suppliers were confident it could be erected in a matter of months and the building completed and fitted out in less than four months. The ODA was unconvinced; it wanted the venue completed 12-18 months before it was needed. To reassure the Authority, Mott
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