No 1 Silo at Cape Town's V&A Waterfront is the second building in the country to receive the Green Building Council of South Africa's six-star green rating – and construction isn't even finished yet.
"Sustainable development and green operations are fundamental to the V&A Waterfront's overall development strategy," says David Green, the chief executive of the V&A. "We have adopted a rigorous approach to green construction and sustainable design principles, and the efficient use of natural and energy resources."
The six-star rating, denoting world-class ranking, is not the only accolade the V&A has received. It got the Eskom 2012 ETA Award in the Commercial Category for energy efficiency initiatives. Eskom established the ETA awards in 1990 to reward exceptional effort in energy efficiency. In addition, in December 2012 the V&A Waterfront was upgraded from a silver to a gold level recipient of the Heritage Environmental Rating Programme.
The construction of the Victoria and Alfred Waterfront began in 1988 by Transnet to redevelop the historic docklands around the Victoria and Alfred Basins as a mixed-use area with retail, tourism and residential components, alongside the continued operation of a working harbour.
It has subsequently become one of the most popular tourist destinations in Cape Town, attracting 1.7-million visitors a month. The basins date back to 1860, when the first load of stone was tipped on to the shore by midshipman Prince Alfred, for the construction of the harbour. The developed site is the size of 180 rugby fields.
No 1 Silo is located in the Clocktower precinct, adjacent to the historical grain silo and elevator building. A unique feature of construction was the raising of the three-storey dust house, a compact building on the site used to extract the dust from the processed grain. It has been suspended on a custom-made steel frame so a parking basement can be built underneath it. It will then become a public lift from the basement to Silo Square.
The 500m² Vodacom Innovation Centre in Midrand was the first building to achieve a six-star green rating, which it received in 2011. No 1 Silo is much bigger, at 18 000m², making it "a very, very significant achievement", says Brian Wilkinson, the CEO of the Green Building Council of South Africa. The council has been in existence since 2007 and is a member of the World Green Building Council. It has given four- and five-star gradings to 30 buildings in South Africa.
The council defines a green building as one "which is energy efficient, resource efficient and environmentally responsible – it incorporates design, construction and operational practices that significantly reduce or eliminate the negative impact of development on the environment and occupants".
"It is very fitting that such a significant achievement was certified in such a world icon as the V&A Waterfront development," adds Wilkinson.
While Green admits that the upfront construction costs are higher, "this is offset against long-term operational savings".
Another structure on the site, the BP Building, completed in 2006, was at the time regarded as the leading green building in the country, says Green. Working in a green building has had a knock-on effect on staff. "The occupants of that building are definitely more conscious of environmental issues like cleaner air, light levels and energy use. We are sure that the same will be said for this building."
Director of VDMM Architects Anya van der Merwe says this is the largest green project the company has completed to date, although it is not its only green project. "It has been an important principle that the environmental response be achieved without compromising the utility of the building, the comfort of the occupants or the aesthetic quality of the building."
The major challenges of the project, she says, have been "to balance the varied requirements of urban space making, heritage considerations, commercial realities and sustainable design".
Energy efficient initiatives
No 1 Silo is the culmination of energy efficient initiatives begun in 2008 by the V&A Waterfront, forming part of the company's "long-term vision and sustainability practices in development, building and operational management".
These initiatives involve an annual saving on electricity of 11 261 449kWh or R5.6-million (US$630 000), while reducing their demand on the grid by 10.5%. The measures are across the board: the installation of efficient lighting and repositioning of light fittings; the installation of meters and development of credible metering and billing systems; and targets in staff performance contracts. "The energy efficient lighting in the parking garages and the shopping centre has reduced consumption by 47% and 73% respectively."
A sustainability committee has been established, and energy efficiency training for tenants in the precinct has been introduced. A future lighting upgrade project will save 3GWh or 3 000 000kWh per year.
The energy-saving measures of the curved, six-storey, glass-fronted No 1 Silo are impressive. Described as "one of Africa's most advanced intelligent buildings", the AAA-grade office building is to be completed around September this year.
It will use seawater from the Atlantic Ocean to reject waste heat from the cooling plant, at the same time allowing for savings in potable water, thus improving its overall energy efficiency. Heat generated in the IT server room will be channelled to the under-floor waterborne heating system to warm the reception area.
The glass façade will consist of 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 façade will reduce the sun's heat into the building while maximising the natural light.
The blinds and double glazing will prevent further heat gain and control the sun's glare in the office space. The under-floor mechanical air conditioning system will supply fresh air into the building, which will then be absorbed as it rises and warms, and extracted at ceiling level, preventing the build-up of pollutants. Paints, wood products and carpets will contain no harmful compounds.
The building has been designed to enhance the outdoor environment: a private roof garden will be planted with indigenous vegetation; a small herb garden will supply the kitchen; and composting units will recycle organic waste produced in the kitchen.
Water and lights
Besides low flow water fittings, a grey water system is part of the design. Waste water from hand basins and showers will be collected and treated, and re-used for flushing the toilets.
Lighting has not been neglected. All florescent fittings have energy efficient, high frequency ballasts. The lighting system is fitted with appropriate sensors, ensuring 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," says the V&A Waterfront.
The architects have not neglected tenants' transport. It will have a secure bike lock-up facility, with lockers and showers for those cycling to work.
The building will use 60% less cement than an equivalent building, and uses FSC certified timber, wood that comes from environmentally sustainable and ethical sources.
The cement content has been reduced by using various replacement products which use less energy to produce.
More than 70% of all waste generated on site is recycled. An innovative feature of the construction site is the use of green hoarding – approximately one third of the site's hoarding is a green, living vertical wall, which contributes to the suppression of noise and dust of a construction site, and provides green spaces within the city centre for pedestrians.
"We are committed to ensuring our environmental and sustainability measures and initiatives are at the forefront of all our business practices," says Green. "This is core to our business ethos and ensures we remain the benchmark for world-class waterfront developments."