;THE ARUP JOURNAL

1/1997 Front cover: Eastgate, Harare: close-up ol la9ade (Photo: Wide Angle) Back cover: THEARUP Aerial view of Bevcan facility, Springs (Photo: Barrie Williams) JOURNAL Vol. 32 No. 1 Editor: 1/1997 David J. Brown Art Editor: Published by Desmond Wyeth FCSD Ove Arup Partnership Deputy Editor: 13 Fitzroy Street Beth Morgan London W1 P 6BQ Editorial : Tel: +44 (0) 1716361531 Tel: +44 (O) 1714653828 Fax: +44 (0) 171 580 3924 Fax: +44 (0) 171 465 3716

Eastgate, Harare, Zimbabwe Eastgate is Zimbabwe's largest commercial ottice and retail Fred Smith 3 development. and the first large modern building in Southern Africa to use natural ventilation and passive cooling without mechanical air­ conditioning. In collaboration with the client and architect, Ove Arup & Partners undertook the mechanical as well as the structural and electrical engineering design for the project, the thermal performance of which since the building opened has been close to that predicted.

International aquatic centres, During the last 20 years Arups has developed considerable expertise Sydney to Bangkok 9 in the design of swimming pools. This article discusses the ventilation Paul Stevenson and water treatment systems for Sydney International Aquatic Centre's unprecedented array of four pools, including an Olympic-standard competition pool and 850m2 of leisure waters, and looks forward to further development of the system design at the Bangkok Aquatic Centre, now under construction tor the 13th Asian Games.

Bridgewater Hall, To replace the ageing Free Trade Hall, the City of Manchester wanted Manchester 15 a new concert hall to match the world's finest , as a home for the Halle Rob Harris and its other orchestras. For the 2400-seat Bridgewater Hall , Ove Arup Brian Lieberman & Partners acted as geotechnical, structural, and full building services etal engineers, while Arup Acoustics created the acoustic environment for the performance of classical symphonic, choral, and organ music.

The Bevcan facility, For this new flagship can-making facility at an industrial township Springs, South Africa 21 some 60km from Johannesburg, Arup (Pty) Ltd were responsible as Barrie Williams principal agents to the client, Metal Box South Africa, for project administration and assistance with site masterplanning as well as the civil, structural, geotechnical, mechanical , and electrical design. and quantity surveying. After four phases and five years' work, the plant is operating to its full production capacity of some 5000 cans per minute.

2 THE ARUP JOURNAL 1/1997 Eastgate, Harare, Zimbabwe Fred Smith

Introduction Modern office buildings in Southern Africa are generally air-conditioned , which means importing capital plant. This makes the air-conditioning sensitive to currency fluctuations , as it costs some 15-25% of the building total , and spare parts are sometimes difficult to acquire. For much of the year, Harare's climate is characterised by generally sunny, warm days and cool nights with temperature swings of )0-14°C, so an acceptable inside environment without conventional air-conditioning was considered possible. To achieve it in a real building , how~ver, needed belief by both developer and professional team. Such an opportunity arose in 1991 with the initial planning for Eastgate, Zimbabwe's largest commercial office and shopping development. The brief was for a relatively inexpensive building with acceptable comfort levels in the offices, without air-conditioning, and without compromising sprinkler protection. For this site, two long narrow 1. Front entrance. the aesthetics and overall quality of rentable blocks gave both the required bulk and good space. The client's bold concept was matched by natural lighting possibilities. By orientating them the architect's enthusiasm, and to these factors along the city's east-west axis, solar gains were was added Arups' experience as structural, limited. Being near the equator, only the east and mechanical and electrical engineers. west fa9ades are subject to strong direct sun . A combination of in situ concrete and double­ The closely co-ordinated design between, and thickness brick in the exterior walls moderates The environmental engineer's main aim was to temperature extremes, and generally light­ total commitment of, everyone involved made achieve thermal comfort in the occupied space, achievable this first building of its kind in Africa. coloured finishes reduce heat absorption. whilst limiting capital and running costs. Ways Precast concrete semi-arch hoods projecting Project outline to limit internal and external heat gains were over windows provide external shading , as well as Eastgate fills a city block near the edge of the investigated, as well as methods of cooling the inter-floor fire barriers. Internal venetian blinds Harare CBD. 140m long by up to ?Orn wide, it building using night-time ventilation. allow occupants to limit indirect solar heat gains consists of two narrow, nine-storey blocks Moderating external heat sources and external glare when necessary. In the covered orientated east/west and separated by a 16m In a moderate climate like Harare's the major street, finishes are as pale as possible so that wide covered pavement with a glazed roof 35m external heat source is solar gain through glazing, reflected natural light can penetrate the full office above. The ground and first floors accommodate and also indirectly from sky and ground depth, while office interiors are also light-coloured 560Qm2 of shops with the remainder given over reflectance. This radiation cannot easily be to render both natural and artificial light sources to 26 00Qm2of offices, the top floor level just shaded, so glazing was limited to c25% on the more effective. The combination of clear glass, within 30m above ground to avoid the by-law north and south fa9ades. To investigate ways to light finishes, and Harare's natural bright sky requirement - and expense - of sprinklers to the minimise solar heat gain, a computer model was provides good natural light in the offices. offices. 332 tenant parking bays occupy two levels used to simulate the solar path , together with below ground , with 93 bays for visitors at first floor various side and top shading devices, and to on the north side of the building. predict internal temperatures. A difference of 1°C Lattice beams spanning over the covered in peak internal temperature was predicted pavement support the glazed roof. Linking the between a well-shaded , 25%-glazed, north-facing blocks together at each level are four sets of open fai;:ade and one with 50% glazing . 2. The suspended 'skywalk'. steel bridges, hanging from substantial bridge beams which contain lift motor rooms and water tanks at roof level. These are spaced at about 35m centres along the building length . At second floor level the cross-bridges are linked by a suspended 'skywalk' running the length of the covered space; this houses the commissioners' desk and security point and is the main entry level to the offices. Access to the skywalk is from the ground level pedestrian mall by an escalator midway along the building length. Mechanical engineering The engineers contributed in many ways to meeting a brief unique in Zimbabwe. The site was large (8500m2) and the three building forms considered (short/squat, tall/narrow, long/thin) all had advantages and disadvantages. Environmenta lly, a short, squat building has the smallest surface area and is least susceptible to external conditions, but its deep spaces need constant artificial light, creating high electricity consumption. A tall building would have good access to natural light throughout but cost more to build and run (eg lifts , etc), and need automatic

THE ARUP JOURNAL 1/1997 3 Moderating internal heat sources was offset by putting the fluorescent starting gear Winter heating The main constant internal heat-source is artificial in the offices' exhaust air path. In the offices. Individual electric room heaters can be turned on lighting. The office ceilings are barrel-vaulted , exposed structural concrete elements are a major by occupants. Power is switched automatically on which suggested uplighting to give a very design feature , forming an articulated surface to a half-hour cycle alternately between north and uniform lighting level, but its penalty was reduced increase the exposed area of heavy mass south wings so that overall consumption and peak efficiency. Cpmputer modelling indicated a elements. This gives the building structure further demand are reduced. Only the low volume fans half-degree rise in peak temperature when the capacity to absorb heat from the rooms . with the operate whilst the heaters are on. thus limiting the lighting load changed from 18W/m2to 25W/m2 vaulted concrete slab soffits absorbing most of the energy required to heat incoming air. A time switch (representing a switch from downlighting to radiant and convective heat emitted by the fluores­ to heater power is over-ridden by a thermostat uplighting to achieve the same level of 400lux in cent uplighters. In this way almost none of the heat which prevents operation above a predetermined the working zone), but most of this additional load from the lights enters occupied space. ambient temperature.

Ventilation and passive cooling

Solar panels Heat energy Glass canopy for hot water heaters absorbed by chimneys to improve stack effect

Stack effect draws air from atrium

3. North/south section showing North lace shading the two blocks provided by linked by the deep overhang covered mall. and planting

E

Foodcourt Parking

Covered Shops Mall Shops

15.Sm 168m 15.Sm

The decision to use natural or forced 4. ventilation had a major bearing on Cross-section the building design . Natural ventila­ through tion implies opening windows. with typical office. consequent noise and dust pollution. wind , heat loss during winter. and security problems, but mechanical ventilation implies significant running costs. The chosen design approach was to develop a pattern of air shafts and air voids, integral with the struc­ ture, which would allow cool air to enter the building at its base and warm air to discharge at roof level. The building would be cooled by the Two lamp fluorescent uphghter flow of cool night-time air drawn Perimeter lamp controlled by photo-electric sw1tch1ng through the slightly warmer building. (dependent on amb1en1 light) Shafts were sized to take advantage of the natural stack effect, although in surrounding main roads. Via filters in external solar gain experienced on were placed precast concrete stools. the end locally-produced fans were the plantroom, the air passes to the each face. Air passes through the with short protrusions on the under­ installed to ensure that the system offices through the network of voided concrete floor and enters the side to increase surface area and could be more easily balanced. concrete and masonry ducts in the office space through low-level grilles also create turbulent flow in the Fans draw fresh air into the plant­ central spine core of each wing. on the external wall under each supply air stream. Since the concrete rooms at mezzanine level some 10m There are four major supply air zones window. The office floors comprise in is at a fairly constant 20°C, the heat above ground floor in the covered corresponding to the building's four situ concrete slabs with vaulted exchange cools incoming air in street. which has cleaner air than the faces, taking into account the varying soffits to form the ceiling . On these summer and warms it in winter.

4 THE ARUP JOURNAL 1/1997 Shops generate enters the ceiling plenum rather than The covered pavement There is a public food court on the first floor, and the occupied space. Tenant-controlled extract Here, the major functions are to provide a retail units on both ground and first floor levels. fans remove heated air from the ceiling plenum sheltered shopping area in the base of the office Mechanical ventilation provides adequate comfort and exhaust it to the outside. At night they are blocks and solar shading to the internal office level for most shops. but tenants can have air­ left on during summer, and turned off most of the fac;;ades , and to prevent convective heat build-up conditioning installed if required. Outside walls time in winter. of the warm air rising from the atrium below. The and shop fronts are shaded with overhangs to limit glazed canopy above the space between the two solar penetration, ventilation air entering shop office blocks is raised over 4m above the adjacent fronts via permanently open grilles, allowing roofs, creating more than 800m2 of open space night-time ventilation. Lights are in a false ceiling , along its edges through which warm air is drawn and manufactured with slots so that the heat they out of the atrium by natural stack effect. The ends of the atrium are protected by waterproof louvre enclosures; these stop rain coming in and allow ventilation of the atrium. The combination of open roof canopy and louvred ends to the atrium allows strong natural ventilation This use of passive cooling, a first in the atrium area but minimises any wind tunnel for Zimbabwe, uses principles Office bay under construction, above 5: precast effect. This large air change rate maintains the similar to those employed in a heat exchange sections being grouted into place, atrium at normal ambient outdoor temperatures range of UK buildings, from Arup and below 6: Finished screeding to precast stools. throughout most of the year, and therefore does Associates' CEGB offices near not generate additional heat in the offices. Light­ Bristol1 to the new Inland Revenue coloured venetian blinds on all office windows HQ2. During the cool nights, the have several functions: they stop solar gain thus system continues to operate. flushing reducing internal temperatures, they absorb stored heat from the building, using sound, which improves overall acoustics, and they Harare's typical daily temperature make for privacy. swing of 10°-14°C to cool the structure. Car parking Car parking above ground is normally preferable A range of Arup computer programs to limit the need for mechanical ventilation. but were used to determine the most parking requirements dictated the need for a effective night-time ventilation rate, a basement. Supply fans draw air from the covered balance between improved thermal pavement into plantrooms at the centre of the conditions and the increased capital Displacement ventilation was basement. Air enters the car park at points along costs of larger ventilation plant and adopted to supply air to the offices the full length of the basement central services increased distribution space. during daytime. This enabled the core, is extracted from brickwork plenums along Computer modelling was also used designers to take advantage of the both external walls, and discharges outside at to determine the sensitivity of the fairly steep temperature gradient mezzanine level. The brickwork plenums were ventilation scheme to the heat between low and high levels to required as a drained cavity for the perimeter transfer performance, insulation of improve comfort further in the retaining wall but, slightly enlarged, could be used heat sources, and building materials. occupied space. as air plenums, thus replacing extensive metal Eventually, a mock-up of a typical ductwork systems. office bay was built to test the Extracting the heat ventilation and passive cooling Ventilation air is exhausted naturally Solar water heating system, and experiments showed by buoyant convective effects, with Hot water is supplied to tea kitchens only. None is 10 air changes/hour to give the best no mechanical assistance. Exhaust provided to the office toilet blocks, and water for balance between cooling achieved air exits the offices through high level the shops and food court is heated locally by and power consumed. Fans were bulkheads in the building core and electric hot water heaters. The water for the selected accordingly. then passes sideways to wide vertical kitchens is heated centrally by solar exchangers exhaust shafts, where velocities are as primary energy source, backed-up by electric In addition. low volume fans were around 2m/s; this made exhaust fans elements in the storage tanks. Time switches installed to provide daytime ventilation unnecessary, the 'stack effect' control the secondary electric heating so that it of about two air changes/hour in removing exhaust air. The natural can only be energised during the night-time the occupied space, which meets pressure differential across the off-peak period where charges are lower. In this occupants' minimum fresh air exhaust air stack is enhanced by the way energy consumption and costs have been requirements. The lower daytime air exhaust 'chimneys' protruding from reduced further. Solar heating effectively reduces change rate reduces the impact of the top of the building. Their surfaces high outside daytime temperatures the electrical maximum demand and hence are heated by the sun, lowering air electricity rates. and extends the storage period of pressure at the outlet to draw air the night-time cooling energy in the Structural engineering upwards through the chimney. The The structure is predominantly reinforced concrete building structure. By thus varying architect has called the exhaust except for the steelwork roof level beam structure the supply air quantity, the computer chimneys 'solar accelerators' - model predicted a 1° c reduction in to the covered pavement and all suspended links, probably the most appropriate stairs and lift cores. Shear walls give north/south daytime peak internal temperature. description of their function . Other advantages were assessed stability to the office blocks, while in the 140m against the additional capital cost of long east-west direction, it is provided by a the low flow rate fans , including: column/beam sway frame . Such a system has 7. uniformly distributed points of stiffness and enables • restricting larger energy- Solar larger spacing of movement joints - a single using fans to night-time when accelerators I central one in this building. electricity is cheaper (and lower maximum demand) Foundations Two proposals were tendered, a concrete strip • reducing the cost of sound and a piled scheme using groups of the augured attenuation for the supply fans 600mm diameter piles then available in Zimbabwe. because the large volume flow rate On return of tenders an alternative was proposed fans will generally be working when with large diameter (up to 1.5m) piles and imported the building is empty machinery and expertise. now available due to the • reducing air speed through the Zimbabwean economy opening up. This scheme supply air grilles during the day, had cost and program advantages. Similarly, thus encouraging displacement an alternative was proposed for the basement ventilation in the offices (enhanced retaining structure, initially designed as a 300mm by maximising floor-to-ceiling thick concrete wall. Here a soil-nailed, augured heights within architectural pile wall with gunite arches between the piles was constraints). proposed and accepted.

THE ARUP JOURNAL 111997 5 8 left: Close-up of roof steelwork showing bridge beams and glazed roof support.

9right: The atrium showing suspended link bridges, lift shafts, and stairs.

Office floors The office structure was the part most influenced by architectural and thermal design considerations. Each wing has a central service core with tea preparation areas. storerooms, toilets, and vertical risers for water. sewerage, and electrical services. The floor here is a double slab structure incorpo­ rating the main horizontal air ducts connecting to the vertical supply and exhaust stacks. There is a one-way spanning floor slab between the central core and the external far;ade beams. This slab is vaulted with an off-shutter finish, its top surface forming the base for the precast concrete stools (see 'Ventilation and passive cooling' panel on previous page). A screed was laid over the stools to form the surface on which the floor finish · tiles or carpet· was laid. The covered street and skywalk Planning constraints required the ground floor mall to be considered as a covered street or pavement, which required its ends to be open but weather­ protected by louvres. No structure except for the escalators and escape stairs interferes with this street at ground level. The skywalk comprises trafficable glass blocks set into 75mm thick precast concrete panels. suspended on a steel frame. The structural aluminium handrails were custom-designed to incorporate all electrical and lighting requirements. To allow movement between the office blocks, all the suspended structures are released horizontally at their supports through sliding movement joints. The main bridge beams are supported on elastomeric bearings. Jacking points allow replacement of bearings in the future. The structure of the link bridges and skywalk allows tor redundancy to permit replacement of cables if necessary. The entire structure can Medium voltage and sub-mains reticulation Shops tolerate removal of any single cable without The sub-mains distribution is via predominantly These have suspended modular ceilings into distress except for the wide section of the skywalk low smoke and fume-sheathed cables , carried by which recessed fluorescent luminaires with which would require temporary support off the a network of horizontal racks and trays in base­ prismatic diffusers were installed. Special task. ground floor. For these hanging structures the ment areas to dedicated vertical electrical risers signage, and decorative lighting techniques were cables are all relatively 'stiff'. which helps to ensure for distribution to sub-mains distribution boards provided to each shop to meet individual tenant that each cable carried a known (and generally and control panels throughout the building. A cost requirements during fit-out equal) load. Installing the cables was therefore comparison between cable and a nsing busbar Covered pavement very much a levelling exercise with no requirement system showed cable to be more economical for This space had to be a 'state-of-the-art' mall in line for stressing or 'tuning' of cables. The cables the building's long, low-rise form. Individual with current worldwide retailing trends. Following themselves have a factor of safety = 6.0. sub-mains circuits are each metered at the detailed and complex calculations. over 30 Electrical engineering main switchboard position, enabling the landlord different luminaires were specified by the engineer Design of the electrical engineering services was to monitor and charge tenants for electricity as part of the mall lighting design required to meet closely co-ordinated with the architect and other consumed. the client's expectations. The lighting was an engineering disciplines to enable optimum design Lighting integral part of the mall design and the overall of the passive cooling system as well as other Basement, mezzanine and roof level result has been very successful. electrical requirements. Here, lighting designs centred around providing Offices High voltage supply and distribution the cheapest and most effective design for The barrel vault ceiling suggested uplighting to Electricity is supplied via a dedicated 11kV durability, ease of maintenance. and low running enhance the ceiling profile and create a quality radial feeder from Zimbabwe Electricity Supply costs. Generally, luminaires with fluorescent lamps lighting environment. A mock-up of the proposed Authority's 33kV/11 kV Manica Control sub-station; (both standard and compact) provided the solution was prepared and a luminaire, through ZESA's existing ring circuit to the area had insuffi­ necessary Illumination levels and met these criteria. many alterations and modifications, was devel­ cient capacity for Eastgate's demands and much Where possible, individual fittings were supplied oped specifically for the application. A special planning and input from the engineers and ZESA via an unswitched three-pin socket for improved feature of the office lighting is that half the total was required to overcome the problems. ease of maintenance. luminaires can be automatically controlled

6 THE ARUP JOURNAL 1/1997 depending on external ambient lighting levels. protection of property and life functions. 104 fire For much of the year the external light levels are alarm zones communicate to central panels enough to illuminate the narrow offices. A four­ which in turn link to a single mimic panel at the stage, highly calibrated photo switch at roof level Commissioner's Desk on the skywalk. provides an energy-saving solution which also The fire alarm system, which is an integral part helps reduce office heat load. of the Building Monitoring System installed at Small power, telecommunications, the Commissioner's Desk, also includes an and data services associated public address and voice alarm The voided floor prompted by the passive cooling system. This covers the ground and first floor design also houses a versatile and flexible small public areas, providing secure, fail-safe, and power, telecoms and data services system, able to highly intelligible pre-recorded emergency speech accommodate any partition and furniture layout broadcasts. An over-ride fireman's microphone and avoiding skirting trunking. It consists of a completes the system. network of galvanised trunking and conduits The size of Eastgate prompted concern about safe linking underfloor boxes equipped with 13A evacuation in case of fire. The engineers decided switched socket outlets, telecoms outlets and a on a 'staged evacuation' system, allowing for the facility for data control, wherever required. safe removal of occupants in controllable stages Fire alarm from various parts of the building. Zones nearest a A conventional hard-wired system utilising fire are obviously evacuated first with less affected manual and automatic detection as well as elec­ zones controlled by the fire alarm control system tronic alarm sounds was installed, offering both then vacated in a prioritised order.

10. Shopping area.

I Building performance 31

29 Construction took from January 1993 to April 1996 when tenant occupation began, ending in September. The ventilation systems are being handed over to the on-site building operational staff as they are v commissioned , and a programme to monitor office climate has been 25 instituted as well as a survey of energy consumption. ~ 11 . Thermal performance Energy consumption 23 Temperature record data Actual energy consumption I vstime: Arups themselves moved into readings are available after the first 21 26 September Eastgate as tenants, and have been six months of building operation. To 1996. monitoring various elements of the make a direct comparison between environmental conditions in the Eastgate and similar air-conditioned 19 offices using both an electronic dry buildings, it was necessary to ignore bulb temperature data logger and a the energy consumption of the wet bulb thermometer. The former shopping and food court areas 17

records several dry bulb temp­ by deducting sub-meter readings. 00:00:00 06:00:00 12:00:00 18,00:00 00:00:00 09/26/96 09/27196 erature readings simultaneously The results are very favourable 09/26/96 09/26/96 09/26/96 Tlme/Oate {Hours:Minutes Month/Day) and can be downloaded to a PC for showing that Eastgate has a graphical plotting of the output data. power consumption of 9.1kWh/m 2 - Room high level temperature lntemat temperature Results to the time of writing have compared with a sample of six other - Room mid Jeve, 1emperature OJwde air temperarure been variable due to on-going Harare developments vary from - Room k>w ~ tempew leve4 temperature - Underfloor temperature reduced cooling of less than 2°c. quality and size.

TllE ARUP JOURNAL 1/ 1997 7 Conclusion Eastgate is unique not only to Zimbabwe but in the region as well. Indeed, there are relatively few published accounts of passive cooling used to the same degree of sophistication elsewhere. As such it is highly innovative and because it was being undertaken for the first time in Zimbabwe, it required considerable originality in design approach. It was essentially the engineering and quantifying of well-known thermal principles, not applied previously to modern developments there. As noted, preliminary climate measuring results show the office environment to be close to expected comfort levels. It is anticipated that once commissioning is complete and fans are being operated optimally, results will be further improved. The passive cooling was achieved using readily available local materials and construction skills. There was no need to import specialist equipment and although the floor 13. Close-up of atrium link bridges. construction was unusual , it was an achievable way of using traditional materials. The early available data indicate clearly that there will certainly be a saving in running and Costing system for the same building. The components, maintenance costs. The reduced energy From the developer's viewpoint, capital cost as including control elements, are relatively simple requirements effect a direct monetary saving well as running and maintenance is obviously devices to make the system easy to maintain. while the relative simplicity of the mechanical ·vitally important in assessing project viability. The capital costs and energy consumption of the plant, namely fans, avoids expensive imported Although suspended ceiling and mechanical plant ventilated system compare favourably with an spares - and all achieved at an overall building costs were very significantly reduced in Eastgate air-conditioned system, a similar-sized example of cost comparable to a similar air-conditioned by omitting air-conditioning, this was at the cost of which would have cost approximately Z$25M building . The economic significance of this is that additional structure. when Eastgate was tendered , with about Z$8.5M it.will help contain building costs, and thus rentals The office floor structure especially constituted an of this in foreign currency. and all the associated downstream costs. It is also important part of the passive cooling design, and The Eastgate office ventilation system tendered at clear that reduced energy demands and reliance as such it was more complex and thus more Z$3M with Z$120 OOO in foreign currency. on air-conditioning have significant environmental expensive than a floor slab in a conventional The requirement to omit mechanical air-conditioning implications. air-conditioned building. Clearly no two buildings needed a modified approach to the standard fee As for the impact of all this on building aesthetics, are identical, but current building cost data agreement. A proposal to handle the more Eastgate shows the architect to have created a show Eastgate to be little different from the cost work/less capital cost situation was put to the unique building that can stand on its own expected for an approximately equivalent client at the outset, with an understanding that anywhere. He managed to satisfy the requirements air-conditioned building . This, together with lower should it prove inappropriate, it could be reviewed of the mechanical engineer for heat reduction in a energy consumption and maintenance costs, and modified at completion. In the event, although way that gives refreshingly new character and clearly indicates the Eastgate approach to be valid acceptable recovery factors were achieved for interest to the fac;ade. for future similar developments in Zimbabwe. structural/civil and electrical commissions, Whilst the concept was initiated using experience Most components in the ventilation and passive Arups' mechanical involvement clearly indicated gained by Arups in the UK, its development and cooling system were manufactured locally, with the need to renegotiate the original fee . This was detail design were undertaken in Zimbabwe. less than 10% of items imported. This compares satisfactorily undertaken, and the Eastgate experi­ Software developed by Arup Research & with more than 30% in average HVAC installations. ence thus provided a basis on which to derive an Development in the UK was used in the initial Furthermore the cost of the Eastgate installation appropriate fee structure for future commissions mathematical modelling to verify parameters, but was about 10% of a full mechanical air-conditioning of this nature. otherwise every aspect of the design process and construction was done in Zimbabwe, which augers well for this approach to office design in the future. References (1) DOWSON, Philip. Offices. The Arup Journal, 1.3;4), pp2-23, December 1977. (2) BERRY, John, et al. The New Inland Revenue Centre, Nottingham. TheArupJournal, 3£A'.4), pp11-17, 4/1995. Credits Project manager and building developer: Old Mutual Properties, Zimbabwe Architect: Pearce Partnership Structural, civil, mechanical and electrical engineers: Ove Arup & Partners John Crack, Olga Djuric-Perie, Joas Musoko, Jon Rapley (structural) Andy Marks (civil) Menino da Silva, Mark Facer, Peter Gundry, Andrew Moore. Nigel Nichols, Daniel Phillips, Darrel Strobel (mechanical) Steve Done, Shaun Landman (electrical) Quantity suNeyors: Hawkins Leshnick & Bath Building contractors: Costain Sisk Joint Venture Illustrations: 1, 2, 8 -10, 13, 14 : Wide Angle Inc (Pet) Ltd 3, 4, 11 ,12 : Nigel Whale/Martin Hall 14. Eastgate fills a city block. 5- 7: Margaret Waller

8 THE ARUP JOURNAL 1/1997 International aquatic centres, Sydney to Bangkok Paul Stevenson

Overview Arups have been involved in the design of swimming pools for many years, at first through structural engineering only. Later, this developed into an integrated building engineering approach 1 with the aim of achieving for clients: • improved environmental conditions, particularly in air quality, water quality, and air and water temperature • reduced energy consumption, costs, and levels of manning and building maintenance • greater 'user-friendliness' for all ages and conditions of swimmer • increased life-span of the building and services. 1. Sydney International Aquatic Centre from the air. A milestone project was the complete structural and environmental services design for Ponds Sydney International Aquatic Centre Forge International Sports Centre2 at Sheffield - completed in 1991 for the World Student Games - Introduction Building details which included a 50m x 25m international pool and 'Aquatic experts' was an unusual role whereby Under a barrel vault roof spanning some ?Orn , a 5.8m deep diving pool. In July of the same year, Arups, as the only team member with substantial several pools are housed: the Competition and Arups' Sydney office began a building services swimming pool design experience, assisted all the Utility pools in the main hall with permanent consultancy with particular strength in swimming other design team members in their work. The seating for 4400 spectators, and the Training pool design. ventilation , condensation, and corrosion concepts, and Leisure pools in the leisure hall. This wide A little earlier in 1991 Sydney, as part of its bid for in particular, were all provided by the firm . As the combination is reputedly unparalleled in the the year 2000 Olympic Games, had decided to project developed, Arups was also appointed to southern hemisphere and probably the world. build a new aquatic centre in the inner western design many of the building's unusual features, Their details are as follows: suburbs at Homebush. The selected site. Sydney including the movable boom, the floating adjust­ • Competition pool: 51 .Sm x 25m, 1O lanes , 2-3m Olympic Park, Homebush Bay, was to house in one able floor, the practice diving bubble, the Leisure deep; used for 50m and 25m short-course area most of the Olympic facilities, including for pool configuration, and all the leisure features. competitions. A 1.Sm wide floating movable the first time in the Games' history all the Key experience had been gained on the Sheffield boom can divide the pool into two 25m pools. competitors. Civil & Civic, who were successful in Ponds Forge project, which Civil & Civic visited • Utility pool : 33m x 25m, 3-Sm deep; used for 25m their tender to design and build the aquatic centre, as soon as they were awarded the contract, began appointing consultants in late 1991 . With short course/training, and diving with 10 boards and used as a benchmark in many of their briefs up to 1Orn high Arups' new building services consultancy up and to consultants. running , the firm was in the right place at the right • Training pool: 50m x 18.2m, 1.2-2.Sm deep; used time to submit proposals for service elements in The benefits to the design team of the Ponds for 50m training and general leisure activities. A the project. and was appointed for two aspects: as Forge experience were many and included the 33m long adjustable floor can vary the depth designers of the pool water treatment systems and unique modified ventilation system, the roof form . from Orn to 2.Sm. corrosion and material selection, water treatment as 'aquatic experts' . The firm was also appointed • Leisure pool: 850m2 of leisure waters, including for the civil engineering design. and distribution analysis, heat recovery techniques, movable floors and boom designs, leisure feature areas for learning and for babies and toddlers, In September 1993, the head of the International design and leisure pool configuration. and various water effects/rides. Olympic Committee (IOC) announced that Sydney had won its Olympics 2000 bid. By this time many Each of these aspects formed an excellent basis potential venues for the Games were designed or for review and development to the substantial under construction, and the Sydney International benefit of the Sydney project. Aquatic Centre was already complete and setting the highest standards for both elite competition and community swimming facilities. The head of Main the IOC was so impressed that he called it the entrance best swimming pool he had ever seen, and as Olympics Chief he has had the opportunity to visit all the world 's major international swimming facilities. No wonder that in the first four months some 350 OOO Sydney-siders visited the centre, Utility Diving and that since then attendances have been Competition pool consistently high. Training pool area pool Following the success of the Sydney Aquatic Centre. the architects - Philip Cox Richardson & Taylor in association with Peddle Thorpe Architects - and Arups were invited by the International developer/contractor Christiani &Nielsen to support them in their bid for the 13th Asian Games, Bangkok. It was successful, and this latest Arup Scale aquatic centre project is currently under 0 50m construction .

r=l Management ~ Change facilities/ ~ Pools CJ Concourse l.!..=1 facilities L__J toilets

CJ Public facilities [::=J Service areas [=1 Aerobics

2. 1992 site schematic. The disposition of principal areas was unchanged as built.

THE ARUP JOURNAL 1/1997 9 Dry duct Warm dry air passes Low air Plenum air conditioning over walls and roof velocities ceiling below seats

24°c )._).. Air and water ).. ).. ·· 2a 0 c - ~- ...... ,,...... - -- ( High moisture zone ··. ' ~

AHU AHU

Buried pipes Pool side Warm surround Water in channel Dry return supply temperature discharges into duct separate balance tank 3. Final ventilation strategy (summer conditions).

6. Competition pool with the Leisure pool There is a range of support facilities for all the As the duct acts as a low velocity plenum with in the background. pools, including accommodation for officials, negligible pressure drop, air distribution through stores, changing areas for both competitors and the high pressure drop slots is self-balancing, the public, marshalling areas, massage facilities , requiring no commissioning . a diving hot tub, spas, saunas, steam rooms, Equally, the supply air is distributed by another meeting rooms, aerobic areas, and fully-equipped self-balancing plenum, this time supplying warm, weight training rooms. A key objective of the dry air at high velocity up over the walls and roof to Spectator air-conditioning design was to produce a facility that met long-term provide a level of fabric protection whilst keeping Various solutions were proposed by the design community needs as well as strict Olympic Games air movement in the occupied zone to a minimum. team, including traditional overhead supply requirements. This was particularly relevant to Comfort levels are therefore high. systems. However. initial computational fluid seating, where by removing the east wall and dynamics (CFO) analysis by Arups indicated extending the seats up an extensive eastern earth The return and dry duct concept became the these to be inappropriate and unable to provide a bank, the normal permanent capacity of 4400 can basis of the solution at Sydney, modified to suit separate spectator environment. Arups proposed be temporarily increased to 12 500 for the Games. the shape of the building and the large spectator displacement ventilation. whereby cool air areas with the supply air at high level at the rear of (at about 20°C) is introduced below the seating Ventilation systems the spectator seating. This solution, however, only at a relatively low velocity. addressed part of the brief, namely the control of The brief Further CFO studies showed this proposal to be The following criteria had to be met: condensation and air temperatures above the water and on the pool surrounds. The different promising, and it was put forward as the design • air temperatures over the water surfaces and on comfort requirements of spectators and swimmers concept to be fully developed and tested. The the pool surrounds to be maintained at about required further development of the system. final under-seating air supply detail was a 'baffled 27°C, ie 1°c above the water temperature air slot', later developed through further CFO • air temperatures in the spectator areas to be at studies by Sydney University. Various types of inlet comfort conditions: around 23°C •• were investigated, including a rear-of-seat supply, a perforated plate supply, and the baffled air slot; • ventilation to assist in preventing condensation

• energy consumption and running costs to be as Baffle low as possible. Plate Conventional ventilation systems for swimming pools provide a common high temperature throughout the whole space, so it was clear that a conventional solution would not be appropriate here and that an original concept had to be 1a0 c developed. Seat Traditional solutions Conventional modern pools generally have well-designed structures and fabric giving good thermal performance, with ventilation achieved Supply through high-level , and corrosion-prone, sheet Plenum metal ductwork. The system increases evaporation by disturbing the high moisture zone over the pool and therefore running costs are high. The metal ductwork can be replaced with grp, but in most cases the installation cost will double. The system contributes very little additional fabric protection. Using this approach, with no in-ground service 4. Under-seating cool air supply. trenches, most of the pool water distribution pipework is buried and very difficult to access at _CFO analysis of under-seating cool air supply. a later date for inspection/repair. 5 Return and dry duct Over the years. Arups have developed the concept of the integrated supply and return air duct system known now as the return and dry duct system. Ponds Forge is a prime example of this. Return air is removed from the pool at its highest level of moisture and contamination, ie at pool surface level, via the level deck water return grating. Water also is removed at this point but the two are separated by the action of the water falling into the return water channel, the return air being drawn off at high level via slots in the return air duct. 10 THE ,.RUP JOURNAl 1/1997 CFO and physical full-scale modelling showed the latter to give the best air distribution and comfort conditions. A problem identified by the CFO modelling was that there appeared to be a tendency for the cooler spectator microclimate to drift down onto the pool surrounds. This was addressed and offset by introducing a warm air supply between the seating and pool surrounds. 7. Utility pool, showing the removable wall for Olympic seating extension. The final result is a unique air distribution system employing warm air to walls, roof, and pool surrounds, providing a low maintenance and low energy system whilst allowing architectural 9. Main hall with extended seating for Olympics. freedom through the lack of exposed ductwork. Air-conditioning to spectators is optional and when operating provides a cool microclimate in an otherwise hot and humid atmosphere suited to bathers rather than fully-clothed spectators.

8. Main hall, with Competition pool in the foreground and Utility pool in the rear.

THE ARUP JOURNAL 1/1997 11 Water systems to 3000 times longer to obtain the same kill. Due The brief to the FINA requirement for low residual chlorine Exacting criteria in the water treatment systems it was soon established that only an ozone were also imposed , including meeting Federation disinfection plant could achieve this. For such a lnternationale de Natation Amateur (FINA) system, a chlorine donor is still required, but only regulations, water distribution to minimise effects for stopping cross-infection in the pools, and this on swimming speed, also 'second to none' water can be achieved by residual chlorine levels of less quality and energy consumption as low as than 0.6ppm. Sodium hypochlorite was selected financially possible. as the residual chlorine donor. An important consequence of the FINA regulation An ozone system has the following specific requirement was that residual chlorine levels in advantages: the pool should not exceed 0.6 parts per million • The clarity and quality of water are very high. (ppm). Traditional chlorine-only plants require • The kill of bacteria and viruses takes place residual chlorine levels around 2ppm, so a more outside of the pool. advanced solution was required. Disinfectant selection • It has low levels of combined chlorine Disinfection and pool water chemistry are the compounds. most important aspects of a water treatment • There are no smells, or respiratory or system and fundamental to designing, installing, eye irritations. 11 . External view from and operating the pool. Chemical treatment is • The atmosphere is less aggressive due to necessary to kill - via an oxidation process - the less-contaminated air. bacteria, viruses, spores, cysts, etc. that might be Ozone gas is dangerous in high concentrations and the recommended exposure limit is 0.1 ppm: present in the water. • High air recirculation saves ventilation costs. levels of 50ppm for 30 minutes can be fatal. Ozone Various disinfection chemicals were considered, • Sterilisation is better. can be injected into the system by pressure or including chlorine donors, ultraviolet and ozone. • Adjacent areas are not affected by vacuum. Here, the latter was selected for safety Table 1 demonstrates the comparative effective­ chlorine smells. reasons, as any leaks in the system will draw air in ness of disinfectants against various organisms. and not leak ozone into the atmosphere. Also for Ozone clearly has a very quick kill time - at 0.1 ppm • Ozone is a micro-flocculant resulting in safety reasons, a detector was installed in each dosing rate, the contact time to kill all bacteria is in better filtration. plantroom to warn against ozone leaks. seconds, whereas chlorine and bromine need up Ozone/chlorine system options Partial ozone Table 1 Ozone cannot be stored but must be Normally when an ozone system is employed, manufactured on site in the quantities required . 100% of the pool water circulated is ozonised . Three types of ozone system, with different costs Organism Disinfectant Dose (ppm) Lethal effect (sec) However, due to the large cost of an ozone and characteristics, were considered: installation, some systems have a partial ozone • single-vessel, to provide filtration , ozone application, commonly referred to as a 'slipstream Coliforms reaction, and de-ozonising all in one vessel ozone' system. This ozonises only some of the Bromine 0.1 18000 • two-vessel, which separates out the sand circulated pool water, which is then mixed back Chlorine 0.1 15000 filtration from the ozone process so that the water Ozone Pool 0.1 5 is first filtered in the first vessel, where ozone is Sampling ...___ added, and then in a combined reaction and ___.. Spores of de-ozonising vessel, the water reacts with B. Subtilis Bromine 1.4 10000 the ozone and is then removed by a Ozone Chlorine 1.4 9000 de-ozonating medium Ozone 0.05 30 • a separate-vessel system which separates out the three processes - filtration, reaction, and de-ozonising - into individual vessels. Virus strains Bromine 0.25-1.0 12000 The two-vessel system was selected for all pools. Sand filter Chlorine 0.25-1 .0 10800 The single-vessel system was inflexible and had a lower performance, whilst the separate-vessel Backwash Ozone 0.05-0.5 120 system was very expensive, giving only marginally Compressed air better water quality than the two-vessel system. 12. Two-vesse

13. Water

10. Leisure pool. including various water rides.

12 scope for a partial system, but only for the large­ the plant must handle. In each pool, a zonal water volume, low-bather occupancy, Utility pool.The supply system was adopted where each area of design of a partial ozone system is not docu­ each pool was treated separately, with its own mented so here the design had to be formulated measured, treated water supply according to the from first principles. The result was an ozonation varying depth of the water. percentage approximately twice that of most slip­ It is important to ensure that fresh supply water stream systems in the UK. Those, however, were reaches all parts of a pool, with particular attention based on empirical calculations, and the Sydney to corners, shallow pools, and leisure pools. In design team was confident that the level of 50% general the lower the residual chlorine content in ozonation on a lightly-used pool was correct at that the pool water, the better the distribution has to be, stage in partial ozone system development. The ie chlorine pools have residuals of about 2.0ppm Sydney project had a larger margin of safety than and ozone pools have chlorine residuals of about general public pools and the 50% ozonation 0.6ppm. Therefore it is important to have better achieves the desired margin. Tests during use of distribution in ozone pools. the pool confirmed Arups' analysis, with the ozone generation plant only ever reaching a maximum of Three systems were considered: 80% full load. • side inlets (only common to the UK and Europe) Filtration • bottom inlets (only common to Australian pools Swimming pool water cannot be considered in various forms) the Leisure pool end. satisfactory if the pool lacks clarity; this can be • a combination of bottom and side inlets due to: (seen as a promising solution to good distribution into the system. This system operates as a normal • excessive bather pollution whilst minimising surface water velocities). one with de-ozonisation, but the central plant is • inadequate filtration and circulation As for water removal , by allowing 70% surface much cheaper than in a full ozone system. The • ex1ernal contamination draw-off and 30% bottom draw-off, the pool amount of pool water ozonated in the:,e systems surface and floor is kept very clear and a good varies between 15-25%; to date this level has been • inadequate or incorrect use of chemicals balance obtained . somewhat arbitrary and the success of pools with • air bubbles. these installations has been variable. To prove that the proposed water distribution was Filtration's primary function is to remove turbidity effective, a full CFO analysis was carried out by the Quantitative studies on partial ozone were under­ to achieve acceptable standards of clarity, and University of New South Wales, the technique's first taken in the UK in 1990, taking into account the conventional systems with pressure sand filters use on designing pool water distribution systems. pool application, bather load, water volume, ozone can deliver filtration rates of 10m/hr - 46m/hr. Analysis of all three systems confirmed that the dosage, bather/m3 water, turnover, flow rates, The higher the velocity, the fewer vessels are selected side/bottom inlet combination would water depths, ozone dosage per bather, etc. One needed and so the cheaper the plant. For public provide both good distribution and low surface particular study by the UK Electricity Council pools like Sydney's, the rates (vessel velocity) water velocities. During commissioning , tests demonstrated that adding a slipstream ozone should not exceed 30m/hr, which ought to give using dyes confirmed the CFO analysis results. system to an existing chlorine pool was effective, excellent filtration . Facilities are provided to reduce pH correction with many advantages only normally associated the quantity of water filtered at lightly-loaded times, with a 100% ozone system. At Sydney, there was Various types of pH correction were identified, during competitions, or overnight, resulting in including hydrochloric acid, sodium bisulphate, reduced filtration rate and substantial running C02, and sodium hydroxide. C02 was chosen , Ozone bypass cost savings. mainly because its use would not add to the total Three basic types of vessel were identified as dissolved solids (TDS) level. appropriate to the Aquatic Centre: pH correction Water heating • steel above-ground vessels At Sydney, water heating to all pools is from a • grp above-ground vessels central gas-fired system via high efficiency, pipeline, stainless steel plate heat exchangers. To pool • concrete in-ground vessels. In addition, surplus waterside heat rejection from Many disadvantages have been identified with the underseating air-conditioning system forms Reaction & Chlorine concrete vessels, whilst extensive corrosion is not de-ozonisi ng donor the primary heating system via separate plate vessel uncommon in steel; grp vessels have over the heat exchangers when the air-conditioning is Backwash years developed as competitors to steel because in operation. they do not corrode. They are more expensive, but ozone system. Pumping systems cost-effective in the long term due to reduced The major users of energy are the pumping maintenance. This being the case, concrete and systems, due to the very large quantities of water steel vessels were rejected, with life-cycle costing at high pressure being pumped 24hrs/day. Various reinforcing the selection of grp vessels. 22 in total systems were investigated including: were installed at the Aquatic Centre, with the largest standing over 4m high and measuring • fixed-speed electric: three one-third size 3.7m in diameter. electrically-driven pumps per system. Water distribution • variable-speed electric: a full-duty variable Distribution of water in swimming pools is a very speed pump with a two-speed standby pump important factor in obtaining satisfactory water • gas-driven engine: two full-sized gas conditions. Here, it was important for surface engine-driven pumps per system. velocities to be as slow as possible in the Gas-driven engines were investigated because Competition pool so as not to impede swimming large amounts of heating are required year round speeds. The first step was to establish the quantity and the surplus heat from the engines would be 'eatures. of water circulating around the system; this rejected into the main boiler return , providing heat depended on bather load and pool depth. to the pools. In this way the heat from the engines Table 2 can be used for the whole of the complex and not Pool Turnover Flow rate Bathers/day just to heat the pool water. A fixed-speed system is be the most usual, so was used as a base to Competition pool 3.5hrs 939m3/hr 5628 analyse capital and running costs. Payback Utility pool 5.2hrs 594m3/hr 3564 periods were calculated, which showed gas­ driven engines to be good against fixed-speed 14. 62Qm3/hr Training pool 3.0hrs 3716 electric pumps but not when compared with the Utility pool variable 672m3/hr speed main pump Leisure pool 1.49hrs 4028 variable-speed alternative. The latter, with the and standby 594m3/h r. two-speed standby, was viable against fixed­ Table 2 shows water turnover, flow rates , and speed pumping, and was therefore adopted for maximum bathers permissible each day for the the Competition pool. A similar analysis for the Aquatic Centre. These rates are averaged for the remainder of the pools resulted in variable-speed whole of each pool to establish the total water flow pumping being adopted throughout.

niE ARUP JOURNAL 1/1997 13 13th Asian Games, employed and developed for the Asian Games Aquatic Centre. Water distribution is similar Bangkok throughout the pools, with some development of the service pipe distribution which here will be fully encased, thus reducing the need for Following the design team's success in acquir­ expensive expansion devices. ing this project, the architects Cox Richardson and Arups were appointed. Arups' scope of The water treatment systems are comparably works included all of the structural elements, world-class, and the systems and plantrooms the pool water treatment systems and some have been designed to accommodate a full elements of passive and acoustic designs. two-stage ozone system, although the ozone part of the plant is likely to be installed at The 13th Asian Games will be held in 1998 and a later date. the project is now well under construction for completion early next year. The total site covers A diving bubble has also been designed some 800ha, with a sports/entertainment for use during practice diving: it will be slightly larger than the Sydney system, to 15. Practice diving bubble. sector, and village/residential sector for 10 OOO athletes. The sports facilities include a accommodate even more wayward diving. main stadium seating 20 OOO spectators, a Heating is always an issue with swimming velodrome, archery and shooting fields, and pools, particularly so in Bangkok with the Other water-related features the naturally-ventilated aquatic centre. which constant high air temperatures creating a As already noted, Arups was also appointed for will seat up to 6500 spectators. cooling problem for large parts of the year. many other features including: The aquatic centre, which is open-air with a Left to their own devices, the pools would be shade roof, houses three main pools: likely to exceed temperatures of 30°C. As FINA • The 25m movable boom for the Competition regulations only permit world records in water pool: this basically consists of a stainless steel, • Competition pool: 50m x 25m, 10 lanes, temperatures of up to 26°C, something had part-floating and part-spanning structure clad in 2-3m deep, and to be used for 50m and 25m to be done. grp sections. Synchronised electric drives are short course competitions This is not a common problem and calculating fitted to both ends of the boom to make moving it • Utility pool : 33m x 25m, 3-5m deep, and used more manageable. the amount of cooling required by the pools for 25m short course/training and diving, with meant the development of a specific computer • A 33m x18.2m floating floor for the Training pool: 10 boards ranging in height up to 10m program capable of analysing the effect of the largest of its type in the world, this is • a warm-up pool: 50m x 25m, 2m deep solar radiation on swimming pools. constructed from buoyant grp sections held throughout, and used for 50m training and The system solution relies on a combination of down at any water level by stainless steel cables warm-up before competition starts. connected to cable drums and electric drives in reverse cycle heat pumps to provide heating a nearby plantroom. The use of the floor makes Many of the highly-developed water facilities and cooling, supplemented by additional gas­ the Training pool very flexible in use. provided for the Sydney project have been fired boilers for the few cooler times of the year. • A practice diving bubble: capable of discharging 1000 litres of air at a pressure of 1000kPa, this creates a very large surface bubble under any one of the diving boards. Lasting four to five seconds, this is enough time to give a 'soft landing' to a practice dive gone wrong. • Leisure features including a 35m flume, a rapid river ride, a variety of water jets and numerous bubble features . Arups also played a significant role in the layout of the Leisure pool and all its features. Summary The ventilation and pool systems at the Sydney Aquatic Centre are almost certainly unique, and represent the highest level of design. Advanced computer technology was used extensively to develop an unprecedented integration of systems in a swimming pool. 16. Artist's impression of Bangkok Aquatic Centre. The ventilation/air-conditioning strategies provide separate macro- and microclimates, achieving comfort conditions for both spectators and bathers. At the same time, the systems provide Conclusion Credits some fabric protection from condensation by The combination of the advanced air and Client: wall/roof washing, and lower humidities due to low water systems described earlier contributed Public Works Department substantially to the success of the Sydney Aquatic air distribution velocities. The air distribution Architect: systems are inherently corrosion-free due to their Centre, described by some as the 'best in the Philip Cox Richardson & Taylor integrated nature and the hall is devoid of the world' It is one of a long progression of swimming in association with usual exposed high-level ductwork. pools that Arups has been involved in, and over 20 Peddle Thorpe Architects years' development in pool design has resulted in The pool water treatment systems are of the refined solutions which continue to develop Contractor: highest quality. Because of the two-stage through successive projects. The Asian Games Civil & Civic ozone/chlorine system, eye, throat, and ear project, which will be the subject of a full Arup Pool treatment, 'aquatic experts ', irritations do not occur in the pool as would be the Journal article in due course, has given the design and civil engineers: case if the system were chlorine-only. The partial team new challenges, particularly with its virtually Ove Arup & Partners Sydney ozone system for the Utility pool is very successful, Paul Stevenson (pool systems) unprecedented cooling needs, but it has every producing high quality water with the plant Henk Buys, Keith Caldwell, prospect of being another world-class competitive generally not exceeding 80% of its capacity. The Tony Phillips. Peter Thornton (civil) swimming venue. distribution systems have been arranged so that Illustrations: no parts of the pool are left stagnant, but with References 1: NSW Department of Public Works surface currents at a minimum to avoid adverse (1) GURNEY, Des, and STEVENSON, Paul. 2-4,12 : Jon Carver effects on competitive swimming. Filtration at low An integrated design approach to the modern low 5, 16: Ove Arup & Partners Sydney velocity results in clear water with 50m visibilities, energy swimming pool. The Arup Journal, 19(1 ). 6-8, 11 , 13-15: Richard Drew substantially in excess of FINA regulations. pp12-15, April 1984. 9: Courtesy of the Architects 10: Patrick Bingham-Hall Energy consumption is at a minimum with only (2) BROWN, Mike, et al. Ponds Forge International microclimates being air-conditioned and variable­ Sports Centre. The Arup Journal, 26(2), pp3-7, speed pumping employed. Summer 1991 . 14 THE ARUP JOURNAL 1/1997 Introduction economic climate the scheme did not proceed The formal opening was on 4 December 1996 by Manchester's celebrated Halle Orchestra had for until 1991 , and then on a revised basis in which the Her Majesty the Queen, accompanied by HRH the many years played in the Free Trade Hall, a venue office blocks (undertaken as a distinct Arup Duke of Edinburgh, after which they attended a much loved but not of the highest acoustic or Manchester office project) were separated and gala concert. comfort standards. In the late 1980s the City subsequently let. The original successful design Council decided to make a new purpose-built team was appointed by Manchester City Council concert hall the focal point of the 'Bridgewater to complete the design so that tenders could be Initiative' to redevelop - with office blocks as well obtained. The successful contractor would as the new hall - an area of brown land , then used become responsible for the design by entering as a car park, to the immediate south of the city into agreements with the design team, an centre. It was in a key position, next to the G-Mex arrangement referred to as a 'switch'. Laing North Exhibition Centre 1 and between the city centre and West won and, as planned, each member of the the up-and-coming Castlefield area, and the Coun­ design team except the quantity surveyor who was cil decided to procure the project on the basis of a retained by the employer, entered into agreement developer/architectural competition. with Laing North West. The design was for a 2400-seat hall, with visitors Work commenced on site in summer 1993 and entering the building through a dramatic glass Bridgewater Hall was completed in summer 1996, prow (Fig 1), and the main services plant located when a successful test concert was held in June. in a glass-clad , free-standing tower to provide acoustic isolation from the concert hall (Fig 2). A team comprising the developers Beazer, the architects RHWL, the theatre consultants Techplan, Ove Arup & Partners as structural and building services engineers, and Arup Acoustics, won the competition, but because of the changing 1 above: The 'prow' at dusk, viewed from the north. 3. Site plan.

2. Rear view from south west, showing free-standing services tower.

THE ARUP JOURNAL 1/1 7 15 5. Foundation column with spring on pile cap (right). On the left is one of the 4. undercroft air ducts. Spring box with cover off.

Protection from external noise The need for quiet Silence - or complete absence of intrusive noise - is an essential acoustic component; anything audible can break the bond between audience and performance. Background noise should be minimised also so that the full dynamic range of 6. The site, looking west, in October 1993. the music can be appreciated. For Bridgewater Some columns already have caps and spring bearings in place. Hall PNC15 - approximately the threshold of hearing (ie silence)-was used as the design criterion. Sound insulation Vibration isolation systems for buildings and Structure The site is surrounded by busy urban roads and is structures often utilise elastomeric bearings or Foundations next to the Metrolink railway. Also. helicopters and pads. In this case, steel springs were selected The solution to the problem of vibration from the light aircraft occasionally fly over at relatively low because they can achieve a lower natural Metrolink explains the unusual choice of foundation altitudes. To achieve adequate external noise frequency (3-5Hz) and hence a better isolation system. Pad footings constructed through up to protection, the lower levels of the auditorium are performance. The helical steel springs are housed 7m of glacial till and made ground spread the load surrounded by ancillary accommodation - foyers, within steel top and bottom plates, forming a from circular foundation columns to the weathered artist rooms, and offices - to form a cocoon. The 'spring box' (Fig 4). An array of 280 spring boxes bunter sandstone which underlies the site. The upper walls and roof are clearly visible, directly were placed on top of the foundation columns columns (Fig 6) are sleeved through the ground exposed to external noise, and are substantial (Fig 5) and the superstructure constructed with a compressible foam which limits vibration double skin constructions with large cavities (also above the springs. One advantage of the spring transmitted from the backfill. Most columns are used as part of the ventilation system and for box design is that it allowed the units to be 600mm in diameter and support vertical loads housing lighting hoists, etc). As well as the pre-compressed at the factory - typically to 80% of only, but 34 (from a total of 159) are 1m wide and massive walls and roof, much attention was paid the expected dead load . Most of the construction designed to cantilever from their pad to cater for to the design of components like doors which can could then be carried out without the need for horizontal forces. They project from the ground into compromise sound insulation, and to arranging the temporary propping to prevent spring deflection. the vast undercroft used to distribute services ancillary accommodation to avoid inappropriate As the building neared completion, the spring beneath the building . Within this space, the top of juxtapositions. units deflected beyond the pre-compression to each column is capped to provide a base for the Vibration isolation their final deflection (c20mm shorter than the bearings to carry the full 25 OOO tonne weight of the The auditorium is some 30m from the Metrolink unloaded case). The sound insulation and vibra­ building ; these bearings contain the coiled springs railway (Fig 3). Both railway and concert hall are tion isolation successfully excluded train noise and that absorb residual vibrations from the ground. founded on sandstone bedrock, through which traffic noise from the hall. Walls vibration transmits readily; if it transmits into a Above the level of the offices which surround the building structure, floors and walls will radiate low inner in situ concrete wall of the auditorium . the frequency 'rumble'. Vibration isolation of the outer skin for insulation against air-borne sound is Metrolink was investigated but could not be a limestone-clad second concrete wall . the space incorporated due to the imminent start of railway between being utilised to accommodate ducts construction. so isolation of the concert hall was 7 below: Long section. from the hall's air-conditioning system. necessary. Although the auditorium is the only space requiring protection from railway vibration , it was determined that the entire building should be isolated, thus avoiding an extensive (and costly) separation joint between sensitive and non-sensitive structure. Detailed on-site vibration surveys when the Metrolink began operation confirmed the need for isolation and indicated that very high performance would be required. This was achieved by carefully designed control of the vibration response of the structure, and by the use of an isolation system with a very low natural frequency.

0 10 20m 16 THE ARUP JOURNAL 1/1997 Mechanical systems The building services systems were designed to stringent noise and vibration limits to ensure that the PNC15 criterion within the hall is not exceeded . The auditorium is air-conditioned by means of a displacement system. The AHUs by the plant towe.r ar~ arranged both vertically and horizontally; running 1n parallel and connected by a plenum chamber they each deliver 11 m3/s of conditioned air at low velocity through a distribution system of acoustically-lined ducts within the undercroft and 1 Chillers 5 Undersea! supply discrete risers to air plenums under the auditorium 2 Plant tower 6 Auditorium seats at each level (Figs 1O & 11 ). Low velocity displacement outlets below each seat distribute 7 High level extract 3 Vertical AH Us the air evenly throughout the auditorium, providing 4 Undercroft thermal comfort and fresh air for the audience. Comfort for the performers is provided by similar 9. Services diagram. o~tlets behind screens around the stage. Return air 1s collected through concealed grilles at high le~el.in the auditorium, using a series of plenums Sound in~ulation is again maintained by a two-skin with 1nterconnect1ng ductwork within the roof buffer 8. Close-up of roof support steelwork. construcllon, the outer skin comprising precast zone connecting to the AHUs via the exposed planks in aerated concrete supported on a steel high level link bridge between the hall and the frame off the top chord of the roof trusses. The void plant tower. Roof between the two layers of roof is used for distribu­ The auditorium roof is a spectacular arrangement tion of services and for access to the winches that The technical rooms , containing dimming and of two way-spanning trusses supported on slender support lighting suspended within the auditorium. amp racks , and musical instrument rooms are columns (Fig 7) close to the perimeter of the air-conditioned by local close control units. 35m x 50m space. The top chord of each truss is a Plant tower The function room and sponsors lounge are plate girder acting compositely with its in situ This free-standing structure. containing the ai~-~onditione~ by individual air-handling plants concrete encasement, and supporting the precast boilers, chillers, associated pumps, booster sets, w1th1n the ancillary plant room in the undercroft. concrete panels that form the faceted inner skin of water storage tanks and calorifiers, is a quadrant on plan, formed by an in situ concrete unbraced The front-of-house foyers and back-of-house areas the roof. The bottom chord is made up of groups of utilise passive solutions to provided a comfortable high.strength steel bars connected by steel frame, arranged on nine levels, each of which houses a specific area of equipment. environment for the occupants, with mechanical castings to the slender cruciform struts which ventilation provided to all internal rooms . space it from the top chord (Fig 8). All these Two vertically-arranged air-handling units (AHUs) In addition to the foyers being naturally ventilated, elements are readily visible from within the audi­ are sited adJacent to, and laterally restrained by, a s~stem of mechanical ventilation assists during torium and make the roof structure an interesting the plant tower (Fig 9). They supply large volumes periods of hot weather with spot cooling to the feature for concert-goers. or air at lo:"' v~locitie.s (again for acoustic reasons) bar areas. The main kitchen. food preparation. Although at tender various schemes were to the aud1tonum bu1ld1ng. In common with kitchenettes and toilets are mechanically ventilated. all services which cross the joint between the considered for erecting this roof, the contractor The central heating plant consists of three 750kW elected to scaffold the auditorium fully and non-isolated plant tower and the auditorium building on its acoustic bearings, a flexible gas-fired steel tube boilers with pressure jet construct the trusses in their final position, burners connected in parallel, providing constant propped from this falsework. This led to the connection is provided at this point. On each side of this connection. and again to limit transmission temperature low pressure hot water to the AHUs interesting situation whereby the foundation with V'.3riable temperature, outdoor compensated, bearings under the stalls area, which were sized of vibration, the services are suspended from the structure with spring hangers over a distance to radiators. The central cooling plant cmprises to su(t the loads from the stalls only, would be two 400kW reciprocating chillers with remote considerably overloaded in the temporary appropriate to the stiffness of the pipe, duct or cable in question. air-cooled condensers, plus a 40kW semi-hermetic ~ondition. Whilst they were strong enough for this. '.3ir-cooled chiller for low load operation, connected 1t was felt that the additional deflection of the The plant tower joins the auditorium building again 1n parallel, providing constant temperature ~prings might cause unacceptably high distortions at high level, where return air ducts are supported cooling to the air handling plants and local close 1n the structure. and confuse setting-out levels of from a services bridge. The connections at each control units. the roof. To overcome this, the affected bearings end of the bridge were designed to accommodate were wedged open until the roof had been movements from the differential deflections of Energy recovery through run round coils and depropped and the scaffold struck. Worries about ihe plant tower and auditorium building , and to free cooling through enthalpy control, ha~e been movements ?f the roof during depropping proved incorporate resilient materials to maintain the 1~corporated within the larger energy usage unfounded: 1t behaved exactly as predicted. acoustic separation of the two buildings. air-handling plants. The auditorium fresh air requirement is controlled by C02 measurement of the return air. A building management system controls and monitors the operation of the building's services.

10. ~all interior, April 1994. Forms for floor trenches to deliver conditioned air 11 . Stalls seat showing acoustic to grilles beneath stalls seats are in place, prior to concrete casting. baffle, with undersea! air grille.

THE ARUP JOURNAL 1/1997 17 Acoustic design Rob Harris

The acoustic brief Design principles Evaluation methods Manchester wanted its new concert hall to be The design as built refined the original The overall form of the hall was developed world-class, of a standard to enhance perfor­ competition proposal : a hall for 2400 people primarily from the combined experience of the mances by the finest international orchestras (an economically necessary higher capacity Mc and RHWL designers, including listening including the resident Halle and the other than the acoustic ideal) with all seats within the and performing in, and empirical comparison frequent users: the BBC Philharmonic and the main acoustic volume. Arup Acoustics (Mc) with , other major concert halls (of both good chamber-sized Manchester Camerata. The brief and the architects RHWL Partnership, took and poor reputation). also required the hall to cater for non-orchestral features of the 'shoebox' form - relatively The design was then tested and developed events - but without compromising the acoustic narrow stalls, and 'cue-ball' reflections from using two main techniques: for its primary function , the performance of overhanging balconies - without the excessive classical, symphonic, choral and organ music. length inevitable in a modern shoebox for • ODEON, an analytical acoustical The last two uses were particularly significant: 2400 listeners. From the 'vineyard' form is simulation computer model Manchester has a great choral tradition , and the taken the concept of breaking up the seating • a 1: 50 scale acoustic model. centrepiece of the auditorium is the major new into blocks (like vineyard terraces), hence The ODEON model used is undoubtedly one of pipe organ, built in the traditional way by Danish introducing additional wall surfaces to provide the most complex computer models ever craftsmen at Marcussen &Son . early reflections, enhancing clarity and devised for a concert hall. 500 reflecting Speech and light entertainment events rely spaciousness. surfaces are incorporated, with over 300 OOO on a high quality sound system designed by The RT criteria set the volume requirement acoustic ray paths calculated and analysed. Techplan. at not less than 24 00Qm3 (the final volume was The acoustic scale model, constructed and Design criteria 25 00Qm3). It was therefore logical to expose the tested in-house by Mc, proved highly valuable Several independent but related subjective steel compression structure within the acoustic in four roles: descriptors are used by concert hall designers; volume, giving architectural expression to the (1) as an acoustic scale model, using MIDAS most (but not all) are quantified by technical structural function . The internal geometry of the impulse analysis software criteria: precast concrete roof was developed between Mc, Ove Arup &Partners , and RHWL to (2) for acoustic ray path tracing using a laser • Ample REVERBERANCE is important in a provide appropriate sound diffusion; an source and calibrated mirror system symphonic hall . Inadequate reverberance interesting feature is the lighting bridge, which (3) for volume estimates by the infill technique results in a too 'dead' or 'dry' acoustic. This is exposed when necessary for non-orchestral (filling the whole space with plastic beads, requires a mid-frequency reverberation time events but retracts out of sight during concerts. calibrated in a 1: 50 scale bin); and not least · (RT) of around 2.0s, which was achieved in A palette of sound-reflective materials was Bridgewater Hall. (4) as a visualisation model for the acoustic specified: timber (good psychoacoustically), consultant, architect, and client. • WARMTH, similarly favoured by musicians and stone, concrete, and fibrous plaster. audience, is provided by a rise in the low Both techniques provided impulse responses frequency RT. Bridgewater Hall has a strong (visual representations of the arrival of sound at bass line (in marked contrast to many major the listener as a function of time) and numerical UK concert halls). values for the technical criteria. • CLARITY must be carefully balanced with reverberance and warmth , to ensure neither over-brightness nor an over-rounded, 'muddy' sound. Clarity comes from strong 'early' reflections following the direct sound to the listener. In the design this was assured by minimising the effective acoustic width of the hall, leading to a high ceiling . • Halls with strong early lateral reflections also provide good SPATIAL IMPRESSION , a desirable aural broadening of the source. Given the 'wrap-around' geometry at Bridgewater, chosen to provide intimacy by minimising the average listener distance to the performers, the sense of spatial impression varies in different seating locations. • LOUDNESS is important to provide an exciting and compelling sound and to allow the conductor a wide dynamic range. This required careful limitation of sound absorption (above what is unavoidably provided by the performers and audience themselves). • A pre-requisite of a great performance is good performing conditions. Optimum ENSEMBLE is achieved by providing appropriate 'early' reflections between performers including the organist. the choir and the conductor. The architectural difficulty of views of the organ from the gallery being obstructed by ensemble reflectors was beautifully solved by elegant glass reflectors which also carry the platform lighting.

13. The auditorium seen from the choir seats.

18 TME ARUP JOURNAL 1/1997 Acoustic testing As is normal in major auditoria, individual The acoustic designer's input to a concert elements like seats (with and without audience) hall does not end with the first performances. were tested for acoustic performance. Prior to Orchestras need time to adjust to a new handover of the building, several test rehearsals acoustic, and listening evaluation continued and a (near-capacity) test concert were held. throughout the first season. These provided both subjective and objective data for subsequent acoustic tuning of the hall prior to the opening season. This period also saw the first recording in the hall, Holst's The Planets, with the BBC Philharmonic. 12 below: Acoustic scale model.

15. Interior of 'prow', showing part of sculpture by Oeryck Healey.

14. Performing area viewed from the auditorium.

THUAUP JOURNAL 1/1991 19 Electrical systems The various acoustic considerations forced tight An analogue addressable fire detection system Though electrical and mechanical services parameters on main cable sizes, lamps and has been provided to L1 standard. using the are an important element in any development, luminaires, dimming equipment, and locations of secure public address system for evacuation. a world-class concert hall raises additional electrical equipment. Operation is manual in selected areas during a challenges. Acoustics being a major consideration, The lighting inside the auditorium is 100% performance. investigations at the early stages of design were tungsten and all dimmable, with facilities for stage Distribution of external television signals, in-house carried out to meet Bridgewater Hall's stringent lighting in the form of booms and distributed video/audio, show relays , and satellite television demands. Electrically, the main issues were: sockets throughout, all individually wired back signals are provided , and a voice/data system has • location of plant to lighting control. The foyer areas are mainly also been installed. Throughout the building , • cable routes and physical sizes tungsten-lit; these are also dimmable, whilst distribution routes for outside broadcast cables the back-of-house spaces and the offices are have been incorporated, together with power • type of lighting principally compact and linear fluorescent. supplies from the concert hall distribution. • specialist lighting control Lighting to the artists' areas is mainly tungsten. A security system incorporating closed circuit Floodlighting and amenity lighting were provided television. monitoring all external and some internal • vertical transport to all external areas. The emergency lighting doors, is also in place. • fire alarms system uses the normal luminaires, together with The lightning protection that has been provided their controls (including dimming). connected to • needs of the disabled. uses the metallic roof and all structural elements. an uninterruptible power supply at 230V AC. The maximum demand was calculated to be rating 70kW, using sealed lead acid batteries for Reference 1500kVA ( 1380kW), though measurements during three hours. (1) McGRATH, John. G-Mex Exhibition Centre, some of the first concerts have not exceeded Manchester. The Arup Journal, 2~ 1) . pp22-23, Vertical transport is provided by two Spring 1988. 650kW, which equates to 270W/seat. 1250kg 1.6m/s passenger, one 1600kg 1.6m/s Facilities have been included for rock concerts, goods/passenger, and one 630kg 0.63m/s which would increase demand to the maximum. goods electrically-driven lifts. with motor rooms Load is derived from a 6.6kV/400/230 single cast­ at the basement level. Once more, special 16. Bridgewater Hall can accommodate the resin transformer rated at 1600kVA, and provision consideration was given to acoustic constraints. largest works in the repertoire: combined forces for linking in an external standby generator up to There is also an external hydraulic 1600kg 0.63m/s from Manchester and Sheffield perform Mahler's the maximum demand has also been included. lift, serving two levels. Eighth Symphony on 29 September 1996.

Credits Client: Acoustic consultant Illustrations: Manchester City Council Arup Acoustics Davi d Anderson, 1: Len Grant, courtesy Richard Cowell. Rob Harris, Raf Orlowski. Bridgewater Hall Architect: Joan Watson Renton Howard Wood Levin (RHWL) 2, 4, 5, 8, 10-15: Theatre consultant.' Consulting engineer: Peter Mackinven Ove Arup and Partners Frank Allum, Derek Bedden. Techplan 6: David Hughes Stefano Bosi, Bill Cleary, Pat Clowry, Gerry Eccles. Martin Lighting consultant: 3, 7: Martin Hall Fenn, Step Haiselden, Bob Hide, David Hughes, Fred llid10. Lighting Design Partnership 9: Jon Carver Jo Massey, nm Mccaul. Chris McCormack, Neil Noble, Consulting engineer for canal works: Steve Peet, Shirin Yoosoofsah (structural) 16: John Peters, courtesy Lee Carter, Alan Foster, Dennis Harrison. Allan lies, Deakin Callard & Partners Halle Concerts Society Andy Jarvis. Paul Sherlock (mechanical) Main contractor: Geoff Balrow, Davi d Harrison, Trevor Wheatley (electrical) Laing North West David Carroll, Brian Lieberman, Norman Snow Structural steelwork contractor: (public health) Jane Collins (geotechnical) Fairport Engineering Ltd Geoff Powell (controls) Building seNices contractor: Barbara Gill (administration) Bailey-Sulzer

20 THE ARUP JOURNAL 1/1997 The Bevcan facility, Springs, South Africa Barrie Williams

Introduction Canned drinks - hitherto a luxury - are increasingly flagship facility at the Nuffield industrial township Five years on, the last of four construction phases affordable by South Africans, and this has led to a of Springs some 60km from Johannesburg, with has been completed: huge increase in demand and justification for new Arups as principal agent. ( 1) a single can-making production line with spatial and upgraded can-making facilities throughout Prior to the Springs project, the firm had been provision for a further line, a coil store, 1100Qm2 of the country. Metal Box South Africa Ltd anticipated involved in a number of can plant schemes warehousing, an in-plant central services building , this potential market increase some years ago for Bevcan involving possible new plants at ancillary plant buildings, offices and staff facilities and embarked on a major construction and Vereeniging and Gaborone in Botswana, and (1991-92) refurbishment programme. a plastic bottle plant at Clayville, also near (2) a separate can end-making facility on an Their plants at Durban, Cape Town and Rosslyn Johannesburg. For various reasons none of adjoining site comprising a combined warehousing were upgraded with new production equipment these was built, the client finally settling for the and manufacturing area, coil store, ancillary and in 1991 they commissioned a new world-class new facility at Springs. services buildings, offices and staff amenities (1992) (3) the addition of two further can-production 1. lines in a fully-integrated extension to the original Administration block: production line and requiring extension of the front entrance. coil store and central services spine and further ancillary process areas. all totalling approximately 1100Qm2 (1995-96) 2. End plant exterior. (4) an 850Qm2 warehouse extension (1996).

Can-making technology The latest high-speed processes quality, consistency, and thickness Currently, the economic viability of and can feel eerie, with seemingly for making two-piece cans of paint coating , and another piece can production in South Africa millions of cans going their various (ie can ends and bodies) use a of equipment that takes five video favours steel coated with tin for ways to the next process on combination of brute force and shots of each can as it passes, can bodies rather than aluminium - conveyor lines without a person in sophisticated high technology. compares them to standard and it is interesting to note that sight! This is probably just as well , The equipment ranges from heavy, pictures. and rejects those not nearly 60% of steel cans are as the few that are involved vibrating plant for stamping and conforming. All these carry out recycled here. At the completed (highly-trained machine tweekers body-making (including 'cupping ' their functions as the cans pass at Bevcan plant the three production and nursemaids) have to suffer an and shaping the can body from a rate of 25/sec. lines turn out some 5000 cans per ambient noise level of 110dB. flat discs punched from coiled minute (1 .Bbn cans per annum). In the production area environment sheet), to the high-speed Such modern plants run with a there is not only noise but also decorating and coating machines. 3. Coil store area. minimum of human involvement vibration. heat, fumes. caustic The process is totally automated, effluent, and plenty of scrap metal with only minutes elapsing - all to be engineered away. The between stamping the initial disc end-making plant, however, is a from the 11 tonne tin plate coils, to much cleaner operation, using the fully decorated can arriving in aluminium as against the tin plate the warehouse palletised, ready for cans. As no decoration or for despatch. Downstream corrosion protection is involved sensors control upstream process there are no applicators and equipment to ensure a balanced drying ovens and far fewer piped flow throughout each production services. The high speed forming line. In-line inspection devices equipment is fully enclosed to include a perforation detector contain the excessive noise (and reject ejector) for the cans. produced and is currently able to an enamelrater that examines the produce 2.3bn ends per annum.

4.Can production schematic. Waste ,,,,,, m1 m1 llll 1 1 1 1 1 1 1 1 1 1 1

De-reeled Cupped Ironed Trimmed Washed Coated Cured Printed Cured Necked Lacquered Cured Palleted in coil store

THE ARUP JOURNAL 1/1997 21 Design team The client's project management and process design was undertaken by Bevtech, their technical services division responsible for new developments Production area 2 and upgrading existing Metal Box facilities in (1995) South Africa. Arups were responsible as principal agents for project administration, assistance with Palletiser site master planning , all construction engineering, area quantity surveying , and resident engineering. The architectural sub-consultants. RFB Consulting Warehouse Architects. were responsible for overall aesthetic (1991) co-ordination and all the domestic people areas. On Phases 3 and 4 Van der Walt and Barry were responsible for electrical work and fire detection. Site preparation and layout The location was previously farmland , and Arups' 50 100 150m geotechnical investigation revealed collapsing soils up to 3m deep overlying ferruginised laterite Stores and material Mechanical workshop strata of varying thickness; the possibility of a D handling D and services perched water table was also identified. The site Electrical workshop D Administration Training, ablutions was therefore prepared for general construction by D and services D and canteen pre-collapsing the upper strata using an impact roller, up to 35 passes being required in places. 5.Site plan. The main foundations, and particularly those to the reciprocating can cupping and bodymaking The production buildings contain extensive ventilation as the initial solution. The system is machines, were founded on the laterite. mezzanine floors, used mainly for can conveying however designed to be upgraded with Numerous solutions for the site layout were to the process equipment. Steel open grid flooring evaporative cooling should the client desire it. examined, the principal objective being optimum was selected as the best medium to provide The displacement system consists of eight placement of all the subsidiary services around the planning flexibility and air movement. constant volume, fan and filter air-handling units production area, while at the same time providing Reciprocating machine foundations were (AHUs) with additional space to incorporate good vehicle access plus circulation and space successfully isolated from the surrounding evaporative cooling if required. The AHUs supply a for contiguous future expansion. The rapid founding material following detailed calculation total 184m3/sec of air into a network of plena and subsequent development of the site took up virtually of the dynamics involved and provision of the ductwork. The number of air changes provided in all the latter except for a possible extension to the required thicknesses of insulation material the new production area below the mezzanine end-making plant. (Tico pads). amounts to 15 per hour. which translates to about six changes for the total volume. Building construction Building and process services Architecturally, the aim was an economical, The mechanical brief required the design of The final air distribution is via Krantz outlets unifying , and attractive aesthetic for all the systems to control the environment in production located below meuanine level and around the buildings by using a common approach to form areas, offices and certain auxiliary facilities. perimeter of the building. These outlets provide and use of materials and colour. Steel-framed 100% outside air at low level , the upwards construction with brick dado walls was used for A major portion of the mechanical work involved displacement of the vitiated air being obtained by the large structures, with the ancillary buildings providing air quality and comfortable working roof level extraction fans.By pumping in more air generally having a concrete frame and roof slab conditions as well as the many piped services than is extracted, an overpressure has been with brick infill panels. needed . created which limits the amount of dust entering Generally, castellated steel portal frames spanning The production area ventilation and air-conditioning the building. up to 40m were used over the production areas, requirements were solved by using an upwards air Air temperature and quality are controlled by whilst the warehouse has a unique all-tubular roof displacement system which was developed from a increasing the supply air through progressive structure comprising triangular lattice purlins and study of the building and the characteristics of the switching of the AHUs. The proportionally high main girders surmounted by roof monitors. The processes it was to house. static pressure drop of the diffusers combined with roof steel mass for the 24.6m square column grid The main considerations were the type of mezza­ the flat performance characteristics of the fans is a very economical 18.3kg/m2, as the rigid trian­ nine floor grid used. the location of occupied enables the system to balance itself at the different gular components required no secondary bracing . zones at ground floor level , and the need to flow rates without the need for complex controls or The 2.5° roof slopes were clad in colour-coated displace process heat and fumes with a minimum excessive use of dampers. galvanised steel standing seam sheets up to 73m of dilution. Certain process machines that create In the production areas the air-handling system is long, which are very difficult to handle ii access is large heat or pollutant loads, eg ovens and spray interlocked with the fire detection system so that in limited. On the final warehouse extension, and machines, were fitted with direct extract systems. the event of a fire , supply air is stopped but the after the sheets were rolled on site. intensive To minimise initial construction costs the design lire-protected extract fans and cabling continue to labour methods were employed to carry each philosophy used mechanical displacement function. individual sheet, 30 men to the sheet. 150m out into the veld and then to slide them up a sloping scaffold ramp on to the roof. It did not save much in terms of crane hire cost but gave temporary employment to some out-of-work locals. The industrial floors were of 175mm thick unreinforced concrete with a dry shake surface 6. Warehouse interior. hardener. The most consistent and acceptable (level accuracy II) floors were achieved by casting large panels, not strips, of about 450m2. The central services building houses production offices, print services. lacquer cleaning areas. and an air-conditioned and humidity-controlled tool care facility for the body maker dies. Because of its close proximity to the production equipment, this building required sound attenuating construction and was fully air-conditioned. The open roof area above was used as an air-handling plant area, feeding directly into the roof space of the adjacent production areas. 7. End plant interior.

22 THE ARUP JOURNAL 111997 The mechanical brief also included piped The compressed air facility incorporates six Electrical services services to the process machines, consisting of rotary screw compressors providing a total of The total electrical demand is 15MVa. The site compressed air, vacuum, chilled water, gas, 3000 litres/sec of dried, oil-free air at a pressure has a duel 22 OOOkVa supply which is reticulated domestic water, machine oils, and lacquer of 8 bars. to the outdoor transformer banks of the can plant distribution systems. All of these had to be All areas are fully sprinkler-protected to Ordinary and end plant, the latter cross-linked to provide integrated and co-ordinated with ventilation Hazard (5mm/min}, as defined by the SA Fire security of supply within the site to both facilities. ducts, fire protection, power supplies and Regulations 10th edition rules. except the ware­ A power factor correction system is installed in both lighting. This aspect was particularly important in houses which are classified as Elctra High Hazard plants. For phases 3 and 4, power is distributed to the highly congested areas below the mezzanine (12.5mm/min). Fire water supply is from two 1.28M the process equipment and main distribution floor and the tight confines of the below-ground litre storage tanks and electric and diesel standby boards by busbar, giving a cleaner and more body maker tunnel, where can conveyors also pump sets which serve separate sprinkler and flexible system than cabling. had to be contended with. hydrant reticulation systems. Fire detection The lighting combination of mercury high bay operates throughout the facility with appropriate luminaires with acrylic diffusers and special rate of rise or smoke detectors, and control and below-mezzanine fluorescent lamps has created slave indicator panels are located at strategic lighting with excellent colour rendition. In the plant, points throughout both plants. The newer phases lux levels are 450 in the production area and 300 in and now the original warehouse utilise fully the warehouse. addressable detectors. The site is particularly exposed and subject to The line control equipment room for lines 2 and 3 lightning which caused many false alarms due to has an underfloor plenum to provide a cooling air surges in the long cables connecting the fire flow through the control panels. This plenum is detection panels. Optical fibre cables are being fire-protected by C02 flooding , which is again installed to avoid this problem. electrically interlocked with the supply air tans, Conclusion the extract louvres, and smoke detectors. The tight programmes set by the client often meant that construction had to start before the detailed design was completed. On occasion this led to 8. Cupping press area. a certain amount of frustration , which was only to be expected , but in general there was excellent co-operation throughout between the design team and the client. In the end he has been well satisfied, with the most advanced plant of its kind in the southern hemisphere. In particular, special thanks are due to the client technical team led by Derek Brown, Graham Lloyd, Richard Stegman, Willie Saaijman, and plant manager Eric Redelinghuis. Credits Client: Metal Box South Africa Ltd Principal agent, civil, structural, geotechnical, mechanical and electrical engineers, and quantity surveyors: Arup (Pty) Ltd Roger Hayim, Jan Hofmeyr, Elaine Lawrie, Gerry O'Brian, Johannes Ramapela, Denise Sanderson, Richard Shedlock, Elvira Tessa (structural/ building) Pat Hing, Karl Lyndon, Roy Morris, Simon Oliver (mechanical) Ric Bennett, Paul Monk, Doug Walton (civil) Sidney de Jongh (electrical) 9. Body making area. Bruce Sulley (geotechnical): Sean Hong, Mohammed Parak, Martin Woodley (quantity surveying) 10. Mezzanine above Neil Glenn, Geof Green (resident engineers). body making area. Architectural consultant: RFB Consulting Architects (Phases 1 and 2} Electrical consultant: Van der Walt and Barry (Phases 3 and 4) Illustrations: 1-3, 6- 12: Barrie Williams 4, 5: Jon Carver

11 below: Cans during processing.

12. Street landscaping. THE ARUP JOURNAL 1/1997 23