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Woode, Diana ; Woode-Smith, Shelley, “No 1 Silo V&A Waterfront Cape Town”, Architect and Builder, Volume 65,
issue 3, (May/June 2014): page 21-38
The new No.1 Silo office building at the V & A Waterfront
has been awarded a 6 star Green Star SA rating for design
by the Green Building Council of South Africa
PHOTOGRAPHY BY MARK HOBERMAN, KATE WOODE-SMITH, LOUISE FENNER-SOLOMON
The V & A Waterfront and the Client entered into an agreement to build an approximately 18,000m2, minimum 4 star corporate office for the Client. The contract stemmed from the Client’s need to consolidate their operations in Cape Town into a single building.
The Client had been assessing the suitability of a number of sites in the greater Cape Town area but had decided to settle in the V & A Waterfront due to the proximity to public transport, shops and parking. In the Waterfront the Silo Precinct was considered attractive as it is slightly distant from the hustle and bustle of the main shopping complex.
The Silo Precinct, adjacent to the BOE building, is considered a link between the CBD & Waterfront. Various options were considered for the office and eventually the site between the existing Silos and Clock Tower retail centre was identified. Using the historically relevant 1920’s Grain Silo and Elevator building as a centrepiece and focus of the entire precinct, a new concept “Silo Square” emerged.
The site is bounded to the north by the Clock Tower Shopping Centre, to the west by BOE, the south west by Portnet’s syncro-lift, the silo complex to the south, Cross Berth to the east and the Collier Jetty to the north east.
The Client requested an open plan office building that promoted interaction, thus increasing operational effectiveness.
The architects interpreted this with the incorporation of a large atrium connected with stairs and elevators. Each floor incorporates pause and/or touch down areas to allow staff to hold quick meetings without having to formally book specific remote meeting rooms. Public and staff areas are located on the podium level at the foot of the atrium to reinforce the sense of activity within the building. At grade, the new building links the podium level (7.3m) of the Clock Tower shopping centre with the ground level (4.3m) of the Grain Silo buildings by means of a broad sweeping external stair to the south of the BOE building. Two levels of basement parking are accommodated below grade, which provides for an additional 650 bays.
The internal arrangement of the 1 Silo building consists of two parts, a west wing and east wing, with a central void containing circulation elements and access to the atriums. The central void recalls the alignment of the previous grain conveyor belt to the Collier Jetty, thus providing visual continuity from the public square to the Jetty. By keeping the cores on the outer edge of the wings and the circulation / fire escape routes to the perimeter of the floor plates, an egalitarian approach is enabled as it ensures that no matter where you sit on the floor plate, you are entitled to a view. Challenges in creating a fully glazed façade were enormous as the climatic influence created all sorts if issues with the working environment. The resultant façade of the completed building is a ventilated double skin glass system with mechanically controlled blinds on day light sensors, thereby creating an energy efficient interior. Strategic internal lighting transforms the new building at dusk. The Living roof “Green Roof”, with its beautiful views of the harbour, acts as a social space for the office, while increasing biodiversity and helping to reduce the urban heat island effect created by traditional roof construction. Conclusion The building seeks to find a balance between the requirements of a contemporary office building and the historic industrial building typologies of the V & A Waterfront.
The aim and intention was to develop the building’s conceptual underpinnings and façade resolution to reflect the inherent integrity of these buildings which were mostly efficient, direct and honest in the manner in which they responded to their often pragmatic briefs. The building is sustainable and well beyond the requirements of “best practice”. A Green Star “as built” rating is currently being sought and it is the first office building in Cape Town to achieve a 6 Star “design” rating. The client’s commitment to the environment ensured that sustainability sat at the heart of the design process.
The development of the new No.1 Silo office building at the V & A Waterfront began with the intention of setting the new benchmark in South Africa for contemporary office design. With its striking design and the award of a 6 star Green Star SA rating for design by the Green Building Council of South Africa, the V & A Waterfront believes that it has achieved this. The No. 1 Silo office development was South Africa’s second 6 Star green office building and the first in the Western Cape. It is also targeting an As Built rating which will be announced before the end of the year. This rating is particularly significant given the scale of the project.
“Sustainable development and green operations are fundamental to the V & A Waterfront’s overall development strategy,” says David Green, CEO of the V & A Waterfront. “We have adopted a rigorous approach to green construction and sustainable design principles and the efficient use of natural and energy resources,” he says.
The No. 1 Silo development is one of Africa’s most advanced intelligent buildings. Through innovative design solutions, combined with proven technology, the building works with the
environment rather than against. It speaks to a wide range of sustainability issues and adheres to the strictest global environmentally sustainable building principles and requirements. Some of the more unique green features are the use of seawater from the Atlantic Ocean, which will be used to reject waste heat from the cooling plant and allows for significant potable water savings and improves the over-all energy efficiency of the building.
Heat generated from the IT server room will feed the underfloor water borne heating system to warm the reception area. Another key innovation of the building is the double glazed double skin high performance façade that has a system of automatically controlled blinds between the internal double glazed system and the external single glazed skin which will track the sun as it moves across the building. The high performance façade reduces solar heat gain while maximising the natural light penetration into the building. The blinds prevent further heat gain and also control the solar glare in the office space. The double glazing prevents any radiant heat loss or gain to the office space. One of the benefits of this façade is to maximise views and natural light throughout the building.
The underfloor mechanical air conditioning system addresses both energy efficiency and good indoor environmental quality. The system supplies cool fresh air from the raised floor, which then absorbs warmth as it rises and is extracted at ceiling level, thereby effectively preventing the build up of pollutants. The architectural vision and mechanical design of the building has ensured optimal indoor environmental quality for those working inside the building so as to promote health and wellbeing. Building users have access to striking external views, ample natural daylight and care has been taken to specify paints, wood products and carpets that contain no harmful compounds that could possibly be inhaled by tenants when working inside the building. Further to this, the building has been designed to also provide quality outdoor environments:
a private roof garden, propagated with only endemic vegetation, and overlooking the harbour and Cape Town City bowl, provides a space for tenants to relax or work outdoors. A small herb garden helps to contribute to the daily food prepared in the buildings kitchen and composting units will, in turn, recycle organic waste generated in the kitchen. In addition to the low flow water fittings that have been specified to promote water efficiency, a grey water system has also been installed to save potable water. Waste water from hand wash basins and showers will be collected, and treated within the grey water system, and reused for flushing water in the toilets.
No. 1 Silo has been designed with efficient and environmental lighting in mind. Firstly, all fluorescent fittings have high frequency ballasts (which are more energy efficient) and highly efficient fittings have been selected. In addition, an intelligent individual addressable lighting system, fitted with appropriate sensors, ensures that lights are on only when they need to be and at the right light levels. Lastly, care has been taken to ensure that no night time lighting is directed towards the night sky in order to reduce night light pollution, which is detrimental to fauna and flora that are sensitive to it. No. 1 Silo also promotes the use of sustainable transport - not only is it located in close proximity to a MyCiti bus stop, but the building design includes a secure bike lock up facility, with lockers and showers, for those cycling to work.
From a materials perspective, the building has been constructed using 60% less cement when compared to a building built according to business as usual. Further to this, the project has supported the use of FSC certified timber, demonstrating that timber has been procured from environmentally sustainable and ethical sources. The construction process has been underpinned by internationally recognised environmental management standards, ensuring that more than 70% of all waste generated on site is recycled. An innovative feature of the construction site was the use of green hoarding - approximately one third of the sites hoarding is a green, living vertical wall, which contributes to the noise and dust suppression of a construction site and providing green spaces within the city centre for pedestrians.
“The building is equipped with an intelligent building management system to helps to maximise the benefit to the occupants of the various green technologies in the building and the opportunities presented by the high performance facades,” says Green.
Brian Wilkinson, CEO of the GBCSA, said, “The Green Building Council of South Africa extends our sincere congratulations to the V & A Waterfront as the building owners on No. 1 Silo for this outstanding achievement. A 6-Star Green Star SA rating signifies ‘world leadership’ and further affirms the Waterfront’s bold leadership and continued commitment to environmental sustainability in the development of this iconic precinct. This exceptional accomplishment is pioneering in that it is the first 6-Star rating of commercial office space of this scale in South Africa and the first building to achieve this rating in the City of Cape Town. We also wish to acknowledge the insightful collaboration between the developer, tenant and professional team involved on this ground-breaking project,” he concluded.
FIRE CONSULTANT’S REPORT
This 30m high building, with its underground parking, office component and adjoining apartment section, required careful consideration be given to fire safety. It was also necessary to take specific measurements to try and reduce capital costs plus make as much of the building area as possible useable space. The General Fire Safety Services As per most high-rise buildings, the following services were provided:
• An adequacy of pressurised fire escape staircases. These all complied with the requirements of disabled persons.
• Fireman’s lifts with their pressurised lift shafts and lobbies that would also be used for the evacuation of wheelchair bound people.
• Full fire separation between the 1 Silo office block, the residential component and the parking garage with individual fire separated areas within these overall fire compartments.
• The building is fully sprinkler protected with hydrants, fire hose reels and portable fire extinguishers.
• Full fire detection and alarms throughout with all the fire alarm / services interfaces in place plus automatic (with manual override) voice evacuation system.
• Smoke control via mechanical extraction in the office block and parking garage. Special Fire Safety Aspects Introduced
The points of interest with this complex that could be considered different from a general fire safety design were:
• The two fire escape staircases on the east side of the complex were for the use of both the 1 Silo Office Block and the residential block in emergencies. One stair is given to the normal vertical travel in the residential block and falls into the same fire division as their (fireman’s) lift. The other is used for 1 Silo internal vertical travel.
• The 1 Silo smoke extraction was designed for the open atrium feature to form the relief air path. The east and west sides of the atrium had their own extract shafts (shared by the AC return air) at the rear of the space. Only the floor with the fire signal, and then only that on the one side of the atrium, had its shaft intake dampers commanded open with all other floors having them motorised closed to draw the air / smoke away from the atrium towards the back of the building. This fire signal also set the change over from normal AC to smoke extract mode and started the dedicated smoke extract fans.
• Special calculations were undertaken to determine the structural stability of the “pods” that extended into the atrium and for the façade Veerendal structure to be of untreated steel.
• Pumps with their specific fire water storage tanks were provided for each of the hydrant and sprinkler services. Each system was given one electric motor driven pump (on emergency power) and one diesel engine pump. These pumps and tanks were designed to cater for the predicted worse case building that would form part of the final development of the Silo Square precinct. This meant two stage pumps, where only the lower pressure discharge port was utilised for the No 1 Silo building. The high pressure port would serve the next development (now underway) which is the old silo building revamp and extensions.
• The No 1 Silo had a piped LPG supply taken off the underground main, fed from the bulk gas tank located adjacent to the Caltex service station, that runs past the site. This had three take-off branches after coming into the building. The one was capped for future extension LPG supply requirements in this precinct, where the other two were for the 1 Silo restaurant kitchen and for the residential block (where every appointment was fitted with a gas fired hob). Leak detection and fire signal interfaces were provided to automatically shut-down either the specific leg of the system, or if a fire occured in the garage where the main gas pipe runs, to lock down the whole system at its main incoming valve.
• There are two emergency power generator plantrooms on this site that are dedicated to 1 Silo with its 5 generators and the other (located in the parking garage) belonging to the V & A Waterfront and serving only the residential block and the large parking garage. Where required, to maintain the integrity of the emergency power to life safety equipment, these cables were fire proofed as they cross spaces not protected from the effects of fire on them.
CIVIL & STRUCTURAL ENGINEER’S COMMENT
Basement Parking Component For the development parking, Sutherland were tasked with the enormous challenge of engineering a solution to accommodate a 2 level basement whose excavations were not only within 15m of the operating V & A harbour jetties (in historically re-claimed land) but, more importantly, were up to 5.45m below MSL. The solution to support the excavations in both the temporary and permanent phases of the project was a key aspect, coupled with the critical issue of solving the substantial drainage requirements in both phases being so close to and so deep below sea level. Heritage buildings constructed in the 1920s, together with operational basements, were underpinned to allow the construction of basements beneath them, thus maximising income generating area. During the operation, the neighbouring Nedbank office block, as well as the Clock Tower Precinct, continued to operate despite the heavy machinery and complex operation which was underway literally within metres.
OFFICE BLOCK COMPONENT
The incredible attention to detail that was effected by the architects to achieve a clean uncomplicated light structure called for some avant garde structural design. ‘Floating’ glass box breakaway rooms were cleverly cantilevered 6m off the main structure and very slender 16m structural steel bridges, together with cantilever staircases, provided linkages between levels within the huge volume central atrium. The external glass façades were supported by a 1,000m2 space truss matrix of slender structural steel spanning up to 30 metres.
To acquire the 6 star Green Rating that was achieved required some very specific input from both the civils and structural disciplines. Contributing factors included the reuse of rubble for the complex underfloor drainage system, as well as the use of re-cycled steel, while pushing the reduction in cement contents to above standard industry norms.
SUSTAINABILITY CONSULTANT’S REPORT
As the sustainability and Green Star consultants on the No. 1 Silo job, the Arup team were instrumental in bringing the client team’s vision of a 6 Star rating to fruition. As consulting engineers, Arup prides itself on good design principles, and the team looked far and wide for engineering solutions that would respond to, and harness the environment of the building. Seawater from the Atlantic Ocean is one of the stand-out examples of a green solution; using seawater to reject waste heat, thereby eliminating the need for potable water in the cooling system and resulting in huge water savings. The system draws cold seawater (normally between 14 and 16 degrees) from the harbour through a titanium plate heat exchanger system in the basement. Another key to the 6 star rating is the façade on the building. The largely glass design presents challenges as it needs to remain as transparent as possible, whilst eliminated glare from not only the sun, but the sea as well. Glass can also add to energy usage due to the need for extra cooling in summer and heat loss in winter. To manage this, the building has a double skin façade on the north east and North West elevations. These have a clear glass outer layer, 700mm outside the main façade – which is double glazed. To deal with the glare, there are automatically controlled blinds, found between the two façade skins, which tracks the sun as it moves across the sky. Many other alternative solutions were sought, including:
• Under floor displacement air conditioning
• Solar thermal panels and heat pumps
• Energy and water sub metering
• Energy efficient lighting and lighting sensors
(only using lighting when required)
• Sub soil drip irrigation and hardy plants used to reduce landscape water need by 50%
• Sustainable use of materials including a reduction of cement usage by 60% and virgin steel to 10%
(i.e. 90% of all the structural steel was recycled steel).
• Intelligent building management system.
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