Balancing the desire for icons with good sense will be key as South Africa warms to the high-rise once more
The evolution of cities and their skylines is never fixed or static. Take Johannesburg. Over the past few decades, the fundamental look and feel of the city’s skyline has changed markedly. It has reached a point where, from certain vantage points, three central business districts (CBDs) are now observable: downtown Joburg proper, Rosebank and, increasingly, the Sandton skyline is starting to dominate.
What is also interesting to note is that, while the initial exodus from downtown was to ‘fat-and-flat’ office parks, Sandton now appears truly to be ready to embrace the high-rise.
Tall buildings are back in vogue internationally at present, and South Africa appears alive to this international property-development trend.
Partly, the attraction comes down to sensible space management.
But urban planners assert that tall buildings can also make positive contributions to city life by serving as beacons of urban regeneration, assisting with changing negative perceptions of a particular area and stimulating further investment.
Further, the design and construction of tall buildings can serve to promote architectural excellence and encourage innovation in building and environmental technologies.
However, by virtue of their size and prominence, such buildings can also spoil the qualities that people value about a place. Individually or in groups, they can negatively impact upon the image and identity of a city as a whole.
So, as South African property developers and city planners prepare for a ‘high-rise renaissance’, what lessons can be learnt to ensure that this desire to go vertical adds to the character and efficiency of our cities rather than detracts from them?
Professor Lone Poulsen, director of the Architecture Programme in the School of Architecture and Planning at the University of the Witwatersrand, argues that high-rise developments can be very beneficial to town planning, if there is a well thought out spatial planning framework for the city.
“High-rises are designated to specific areas where development is more concentrated and integrated and where there is a need for more efficient use of valuable and expensive land, such as central business districts and mixed-use nodes,” says Poulsen.
She adds that there have been both success- ful and unsuccessful high-rise developments in the past, from which lessons should be drawn.
“Any dense environment needs to be well designed, well maintained and well managed.
“High-rise buildings designed in isolation from each other tend to be iconic or symbols of power, whereas high-rise development considered as city blocks with buildings adjacent to each other tend to be about creating a sense of urbanity,” she argues.
Poulsen notes that these developments should also anticipate the need for other related facilities and amenities, such as public transport, social facilities and public spaces.
“This is particularly important in the design of high-density residential developments. People who live in confined spaces without contact with the ground need to have an escape in terms of access to both commercial and social amenities. There- fore, changing an area from [being] low-rise low-density to high-rise high-density requires a simultaneous development and reservation of land for these other communal facilities and public open spaces.”
A key advocate of more high-rises, especially in the fast-growing Sandton CBD, is Liberty Properties property development MD Caswell Rampheri.
He says the company is part of an ambitious development plan in Sandton, but assures that the group is sensitive to the socio-economic benefits and constraints.
“The City of Johannesburg would like Sandton to densify, and given land-availability constraints, the only option is to go vertical.
“This will ease the pressure on land that could be used for roads, parks and other services,” Rampheri outlines, arguing that the “time is right” to go vertical.
The plan, however, will be advanced in phases. Initially, the focus would be on a R1,77-billion refurbishment of the existing Sandton City centre, with the addition of 30 000 m2 of new retail space, improved access and additional parking bays.
Liberty Properties hopes to have 95% of the upgrade completed in time for when the 2010 FIFA World Cup takes place, when construction will be halted temporarily to accommodate the increased number of visitors. By April 2011, it is expected that the project will be entirely complete.
But this is only the first of three phases, with the second and third phases likely to include the construction of a new 80-storey office tower, which will be the tallest in Africa.
The office tower, which will be significantly taller than the 50-storey Carlton Centre, currently the continent’s tallest building, will offer a walkway to the nearby Gautrain station, a new hotel and residential apartments.
Phase three may involve more residential properties, but this is dependent on market demand.
The development, which was unveiled earlier this year, has been three-and-a-half-years in the making, and included “extensive research and consultation”.
London-based RTKL Associates, an award-winning global practice of architects, planners, engineers and design consultants, has been chosen as the complex designer. RTKL is also the designer of the Beijing International Sports and Exhibition Centre, which housed the 2008 summer Olympics.
The practice has also designed the Gateway Shopping Centre, in Umhlanga, Durban, and is the designer for the new Twin Towers precinct, in New York.
The project will be a major next step in the evolution of the CBD, which, since Sandton City opened in 1974, has transformed the previous tranquil semiagricultural district into a bustling precinct, with more than 1,2- billion square metres of commercial space.
Rampheri believes the development will “adopt a reasonable amount of green principles, especially energy efficiency” and says it will be benefit from facilities such as the Gautrain and the rapid bus transportation system, to improve the overall functioning of the CBD.
CAPE TOWN’S PLAN
But Sandton is not alone in trying to reshape its skyline: Cape Town has given the go-ahead for a R1,2-billion, 148-m-tall mixed-use development, which, once completed, will hold the accolade of being the city’s tallest building.
Economic confidence and the demand for offices and hotels in the CBD are major drivers of the Portside development.
The Old Mutual Investment Group Property Investments-backed development will comprise 24 office floors (33 000 m2) above a ten-storey hotel (14 000 m2) and retail component (2 500 m2), with parking on five basement and eight above-ground levels.
Property development executive Brent Wiltshire says the group hopes to have the building completed in 2011.
Portside will be built on a 6 500-m2 block, between Hans Strijdom avenue and Mechau street, along Buitengracht and Bree streets. The city sold a 3 500-m2 site to the Old Mutual group in May last year, for about R89-million, to make up the block.
Wiltshire says Portside will be an “elegantly proportioned, environmentally sustainable, mixed-use tower of 148 m in height”, in an area of the city where the surrounding spatial infrastructure of wide roads and public open spaces supports such high-rise development.
“The development and professional team is investing many hours on improving the rating of Portside against the current rating tool of the Green Building Council of South Africa.
“Already the electrical and mechanical engineers advise that the running cost per square metre of Portside will be lower than that of the benchmark, a 15-year-old office tower,” Wiltshire enthuses.
The building’s footprint will also be modest and shaped so as to maximise northern and southern orientation and minimise west and east exposure in a bid to raise the development’s electricity efficiency.
TALL BUT GREEN
City of Cape Town director: spatial planning and urban design Cathy Stone says that there has been significant and exciting innovation internationally on the development of ‘green’ tall buildings and certainly there is a lot of emphasis on such developments.
“There are, however, some fundamental realities about tall buildings, which detract from their becoming very green – for example, they require lifts, which three- or four-storey buildings don’t necessarily require,” says Stone. But she adds that there have been exciting innovations internationally to develop more sustainable and energy-efficient tall buildings.
“Suitable technology does exist and the city will encourage developers of tall buildings to explore alternative technologies and appropriate designs that contribute to mini-mising energy demand and consumption,” Stone adds, noting that proposed developments of which the electricity requirements exceed 100 kVA must obtain permission from the relevant electricity service provider.
But Poulsen says that there are no easy answers to this challenge. High-rise developments can use energy and resources more efficiently but can also put a strain on overall resources. High-rise developments can set a green building precedent with better use of resources and energy but this comes at an upfront cost, which needs to be recouped over time.
“The whole issue of sustainability is about a much bigger picture evaluation of the way in which resources should be used – short-term gain against long-term costs.
“More dense developments, in principle, use resources more efficiently, but this needs to be seen as the interrelationship between valuable land, the cost of development, affordability, available resources, infrastructure needs, public [versus] private transport, as well as economic and social needs.”
She notes that whether a development is high rise or low rise, or anywhere in between, is not the issue.
The quality of any urban environment is dependent on the long-term vision for the city, the urban design framework, the regulations, which govern the pace and type of development and the political will to attain that vision, combined with private-sector awareness of what constitutes good city living against development purely for the sake of profit.
This should ideally be seen as a collaborative venture rather than a conflictive relationship between public- and private-sector investment.
“I do believe that we have the expertise to do high-rise development in this country and we have professionals who are up for new challenges in terms of design, structure, technology, and green building issues.
“However, we definitely have a shortage of built environment professionals and there is some discussion between academia and government about how to provide more support and opportunities to educate more built environment professionals.”
The City of Joburg’s development planning and urban management executive director, Philip Harrison asserts that, for a high-rise to be green, the design and use of materials must take sustainability into account.
He notes that there are high-rise buildings in parts of the world that are highly energy efficient and ecoresponsible, such as in New York and Chicago.
“We will do our best through providing guidelines and through regulation to ensure that the new stock of high-rise buildings in Johannesburg is as ecofriendly as possible,” Harrison avers.
But his department is also actively promoting higher densities across the city, and especially in areas that are well connected to existing and new public transportation networks because Johannesburg has one of the lowest densities of any major city in the world.
Harrison says that higher densities mean greater efficiency in the use of land and bulk infrastructure, more viable public transport systems, and also better levels of servicing for communities to support facilities such as schools, hospitals and libraries.
However, he is quick to add that increased density does not necessarily mean ‘high rise’. In many places, increased densities may mean walk-up apartments, or rental accommodation attached to owner-occupied houses. There are certain parts of the city where only high-rise development is currently supported, which include the inner city, and the precincts around the Gautrain stations.
High-rise development is obviously not beneficial in all areas as there are significant constraints in terms of geotechnical conditions, bulk infrastructure and road capacity.
Higher densities are more efficient in terms of the provision of services and infrastructure, and ensure that development takes up less valuable land.
“However, we cannot generalise as each type of infrastructure has its own optimum capacity. We need to look at every area and ascertain what can be supported in terms of power, water, stormwater and sewerage.
“Higher densities provided by high-rise development also provide the size of population to support high-order facilities including, for example, secondary schools and hospitals, and make public transport more viable by increasing ridership,” says Harrison.
High densities support the ridership required for public transport. In terms of land use, higher densities allow for the possibility of mixed-use developments. With mixed use, an ordinary citizen has access to a wide range of services and facilities, such as accommodation, schooling, clinics, retail, civic services and entertainment.
DON’T SPOIL THE VIEW
Of particular concern to Cape Town is the protection of views, particularly of, and from, the iconic Table Mountain, which is also a World Heritage Site.
Cape Town, as a city, is not defined by its urban or built skyline and it is not intended that it will be so in the future. The Table Mountain skyline is the defining element that makes the city unique and views of it from within the CBD, as well as from afar, must be protected.
But Stone argues that tall buildings also often fail at ground level. This impacts negatively on pedestrian movement and the quality of the public realm by giving limited focus to place-making and the type of activities that occur at ground level.
“They are often conceptualised in isolation of the local context, with little attempt to achieve spatial integration because specific emphasis is placed on achieving iconic or individualist status, to the detriment of the overall character and performance of an area.”
She adds that tall buildings that generate additional bulk will also impact on infrastructure capacity, parking and traffic management, and should also be assessed in the context of the city’s future proposed densification strategy. Microclimate issues, such as overshadowing and wind, that directly influence the performance of comfortable streetscapes are of particular concern and need careful management within the Cape Town context.
Harrison points out that the most obvious challenge is congestion, as high-rise development must be associated with public transport or improved road capacity.
“Significantly increased densities must also be linked to the provision of green lungs: the higher the residential densities, the more green space and public space must be provided.
“We cannot simply reproduce an urban jungle. Then there are real constraints in terms of infrastructure; existing infrastructural capacity can only support high-rise develop- ment in limited parts of the city. There are also geotechnical constraints: geology and soil conditions cannot support high-rise development everywhere.”
Poulsen points out that for this reason, the built environment that results from denser development needs to be considered carefully in terms of impact on sunlight, climate, orientation, public amenity and open space.
“A balance is required between built and unbuilt space, the scale of streets and the pedestrian environment, useable public space and the green amenity. Urban design is the framework that coordinates individual developments into a coherent and appropriate built environment. The denser the built environment, the more critical it is to have a good urban design framework to guide the relationship between existing and new development.”
Wiltshire assures that Portside has sought to address the issues of shadow, wind, lift speed, fire and safety. Portside has the advantage of being sited on three of the widest streets in Cape Town and there are large spaces separating the development from most of the surrounding properties.
In contrast to a squat building, Portside, as a tower, will cast a narrow shadow – and that in an area with wide streets. The shadow impact on neighbours has been tested through computer modelling over a 365-day period – the effect is minimal. In addition, a wind study has been conducted by the Council for Scientific and Industrial Research.
There will be dedicated lifts for the hotel and office tower and lift studies are being conducted to determine a benchmark for lift waiting times. As part of the focus on safety, lifts can be stopped every third floor to gain access to an emergency exit from within the lift – that is, without exiting through the lift doors.
But for the present, there is still no clear basis or protocol for determining whether a tall building is appropriate for, or beneficial to, the overall functioning of a city or for mitigating the possible negative impacts of a tall building.
South African cities are, therefore, contemplating policy frameworks to guide tall building applications.
Such policies would be both a protective measure and a means to ensure that the opportunities created by a new development of the magnitude and scale associated with tall buildings are optimised to improve the overall experience and functioning of the city for all its users.