The Constantia Sports Centre, Cape Town, South Africa.
Competition win, client: Private, estimated cost R150-200,000,000 (ex VAT), proposed Public / Private Partnership with City of Cape Town.
Brief: New proposed bulk real-estate surrounding 2x existing oval cricket pitches.
WHY A NEW SPORTS CENTRE IN CONSTANTIA
The Constantia Sports grounds are one of the most prestigiously located areas of real estate not only in Constantia, but probably in the whole of Cape Town. A very careful thought and consideration was placed into the proposed brief to include an additional 8000 square metres of bulk onto the grounds. The impact that such an open, lush and park-like nature has for these sports grounds is crucial to the nature of the urban environment it currently demonstrates. It’s this nature of the entire grounds that was realized by ourselves that gives the precinct its character and high-value to its location. We have been made aware in the brief that the grounds currently are not achieving a suitable rate of return on investment with the buildings that occupy the spaces are the grounds, and understand the need for building development and re-investment.
In considering the two very fundamental aspects of the above. 1) The lush-park like nature of the grounds and 2) the need for building development, although seemingly contradictory, warrants a more very carefully considered approach to develop a concept that strengthens both. A secondary fundamental principle in the development of additional building area for public use is the provision of parking. With the provision of a sports centre, conference centre and flexible offices the need for 20 bays per 100 square metres would be a minimum. Hotels a minimum of up to 10 bays per 100 square metres and offices 5 bays per 100 square metres. Needless to say there would be a fair amount of underground parking to be proposed with one of the briefs major criteria’s in the development requiring minimal visual impact. With the proposed bulk requirements up to 2-3 storeys of basement parking may be required in addition to potential surface parking, although our primary concept is to eliminate the view of car parks to strengthen the park-like nature of the grounds.
As a result the Sports centre, hotel and office buildings may require a multitude of basement levels based on parking requirements, but there would be middle ground as to how many levels of basement based on how much bulk is developed and what return on investment the building could achieve with its rental returns without over-capitalizing on basement costs. Without reviewing a concise feasibility it would be estimated that 2-3 storeys of basement parking may in all likelihood be considered in our experience in feasibility and our concept graphically follows this suggestion.
Our primary concept and solution is to dig up the earth and re-use around the new proposed buildings to blend the new buildings seamlessly into the revised but maintained lush and park-like surroundings of a green grass landscape. The concept is also reinforced with a proposed green roof with landscaping and a concrete slab. The advantage with the green roof is its rain water attenuation, the absorption of the buildings into the landscape, elevated viewing platforms for improved cricket viewing vantage points, blending in with the environment and reinforcing the park-like nature of the grounds, reduction of reflected heat energy into the surrounding area (mitigating urban heat island affect), enhances insect and bird wildlife biodiversity / proliferation for the area and a longer lifespan than traditional roofs (metal sheeting or other tiled), less maintenance obligations and a positive environmental stewardship for the City of Cape Town. A 5-star rated green building rating would also be of a minimum standard acquired within a reputable and highly historically-valued area of Cape Town that would also reach international standards. Upon view of the sports ground moving south bound from the M3 currently there would appear to be very little change to the landscape view after completion in its greenness an integrated nature with the landscape.
This reinforces the requirement to be low in visual impact and will sensitively provide less obtrusive buildings to existing surrounding neighbour environments. What is also to be considered is the level of originality that this concept acquires. The Constantia Sports ground is prestigious in history and location and nothing would be more fitting to present a concept that would be world class in green technology, energy efficiency and responsibility and originality. The real estate value created in the eccentricity of concept would leverage its property value exponentially. Also emphasizing and adding more landscaping, more viewing platforms for the public, and reinforcing an even more so park-like nature to the entire grounds. The surruonding additional landscaped areas around the buildings will also create effective sight and sound barriers from traffic noise around the sports ground along the M3 highway, the enveloping off-ramp and Constantia main road.
Also presents a constant criteria of utmost importance to consider. With these weather challenges in mind the green roof is considered as a valuable tool in conservative collection of storm water where the water will be attenuated and stored in ‘Jojo’ tanks concealed within the new surrounding landscaping and used to re-supply water into the cricket pitches. The grounds are also fairly close to a high water table in the area and an additional drainage supply would be introduced to re-circulate ground water into the grounds irrigation system. Upon investigation into green roofs technology and their introductions into the South African market the following was concluded. Green roofs have received a poor reputation due to the fact that the plants die early and present themselves as a fire hazard. They are also considered high in maintenance with required irrigation systems.
Whilst investigating these concerns the following was concluded by green roof technology consultants. That the correct choice of plant eradicates the concerns in plants dying and that the correct choice of planting increases the longevity of the plants lifespan.
The correct choice of plant also concludes a necessity to only be watered during specific shorter periods of summer if required. So the use of the correct types of plant species concludes the success to a low fire-risk and heavily irrigated green roof system. An investigation was also performed with the green roof system over the buildings and an energy model procedure was performed with the concept. It was concluded that the green roof technology has the best performing total energy consumption per kilowatt hour in the use of the buildings when calculated relative to traditional roofs and metal roofs. The conclusions were that the green roofed buildings would provide the most cost effective solution relative to the buildings energy costs post-10 years. It was also considered that the additional weight of green roofs could present an obvious threat to such a concept and this is eradicated by the use of correctly chosen low-weight soil and suitably light green technology. Also presenting conclusions that an efficiently designed structural system would cater for any unnecessarily added structural weight costs.
The amount of earth that will be required to be dug out in order to achieve the parking requirements would be substantial and considerable thought was given in how to re-use or maximise the incentive to retain the earth as cart-away soil and material is expensive. We have seen what a substantial saving Elon Musk created by re-using launching rockets of pay-loads into space by bring thruster rockets back to earth. This concept could be well considered.
In reviewing the costs per cubic metre of soil being carted away relative to maintaining it at ground level it becomes opportunistic that there would be a substantial saving. Cart-away rates are in the region of R450/cm with excavation works around R100/cm and earthwork massaging R80/cm. Concluding a likely rate saving of R270/cubic metre in retaining the dug up earth on site being strategically positioned at surface level. So in the case of considering around 70,000 cubic metres of bulk earth to be dug up for 2-3 storeys of basement parking for the required areas, this would equate to around a R18,900,000 saving. Whilst strengthening our concept in building the spaces within the ground as the concept requires earthworks to be built around the buildings to help embed the new spaces into the landscaping and ultimately reinforcing the brief requirements for low-visual impacts by blending the buildings into the landscape. The 2-3 levels being considered equates to around 20,000 sqm of basement parking, or R120,000,000 worth of basement construction (R6000/sqm basement parking). This would finally equate to about a 15% saving in costs by re-using the uprooted earth around the buildings. In addition to the cost savings we believe the guarded surrounding earthworks built around and embedding most of the buildings would offer more efficient cost savings (retaining walls/engineered retaining wall systems/grass/enlarged perimeter cavities) relative to the likelihood of double glazing being required to a substantial area of the building adjacent highways and heavy traffic main roads.
There may also be an option to re-use the bulk earth in the production of bricks required for the developments masonry walls as the sub-soil layers are potentially rich in clay. This could also be an opportunity to get the local community involved too. Similarly to the way Elon Musks The Boring Company are re-using and re-selling the dug up earth from their boring tunnels to make a return on the works.
The intention to introduce passive ventilation solves damp issues in high raised surrounding earth walls where a perimeter duct is used to naturally ventilate hot air out the building. It is also used to dramatically reduce the mechanical ventilation costs of the building. The passive ventilation system simply utilizes a perimeter cavity wall closer to 300-500mm in width as opposed to traditional 50-100mm, with cool air inlets within the surrounding fenestration. Cool air is drawn in via window vents at low floor levels and hot air is exited via return ducts in the ceiling and out through the perimeter cavity duct. Although air-conditioning ventilation systems may well be introduced, their necessity will be dramatically reduced during extended periods of the year. The Pierce Partnerships Architects building in Harare, also referenced in presentation which works similarly to an ant hill in sub-Sahara Africa, is also used as a precedent example of the methodology in passive ventilation.
Passive ventilation may also be considered for the lower level basements, especially below the Sports Centre where the basement levels have the ability to be ventilated on the west face with ground levels well below the adjacent cricket levels, however, passive ventilation strategies will only be efificent enough for above basement levels. Minimum fire regulation requirements will not be feasible with passive ventilation only for fire and smoke extraction to basement parking levels. The passive ventilation will have a major impact in reducing energy costs to the building as well and make the building financially feasible post-10 year period.
The shape of the building both vertically and in plan is purposeful in its serenity. Positioning new commercial buildings within a lush, park-like location would be best suited in being carefully considered and very sensitive in approach. Existing landscaping lines portrays curvilinear edges and paths. The cricket pitch is well-rounded in shape and circle. Positioning a building with sharp edges, orthogonal lines and 90-degree corners comes across as too formal, blunt, over-bearing and incongruous to an existing sinuous landscape. By forming new building edges with rounded corners with a diameter radius of no less than 8 metres, these forms seem to marry together well with both the landscape as well as the softness of the ‘green roofscapes’. A proposed curvilinear building form approach also unifies the building well in the nature of its surroundings. It also reflects the same form accent as a the round cricket pitches, a cricket ball’s curvilinear shape and a cricket balls overall trajectory through space. All accents of forms coming together with sight and feel.
Each building places a significant importance on the views out towards the Hottentots Holland and Constantia mountains. They do so not only in the dialog of their elevation facing south-eastwards, but also in the way volumes are created within the building designs. In the Sports centre, floor plates are higher levels are cut-back for two reasons. One to bring the cricket viewing experience in the clubhouse internally into a restaurant/clubhouse ground floor area, but also to create additional perimeters upstairs that would take advantage of the mountain views from the sports centre floor and flexible office floor at the upper levels. The hotel is also purposefully divided into 3-wings to create additional window views around all 3 perimeters. This also creates an Italian-style, internal courtyard for the hotel increasing the value of each boutique suite all the way round each wing and also presents more opportunities for more rooms to take advantage of views towards the cricket pitches. The main office building positions itself well at the higher level of the grounds and elongates its wing north-south to make maximum advantage of more perimeter window facades facing the cricket pitch and the mountain views. The top penthouse style level of the sports centre opens out to a green roof space that looks out towards the south-east mountain range and could be used for a variety of spaces such as conferencing, boardrooms or even flexible serviced office spaces.
TECHNOLOGY & RESEARCH
The ’TENSARTECH PANEL’ and ‘GREENLOCK’ retaining wall system is available in South Africa which can dramatically reduce the costs of traditional ‘Loffelstein’ walling and creates earthed, landscaped side walling wall construction. ‘Versidrain’ products are used for efficient storm water attenuation into storage tanks. ‘Environmix’ products can be used for lightweight organic planting for grass. Green roof rainwater systems are adopted and consulted by the MRC Group in South Africa. Recycled concrete can also be adopted and has been well received by the Green Building Council. Floor and roof slab concrete has the ability to include 25% Ground Granulated Blast Furnace Slag or 30% Pulverized Fly Ash in lieu of traditional Portland Cement. These forms of cement replacement significantly reduces the overall carbon footprint of the concrete construction and helps to reduce risk of air and water pollution. References and material are provided with the presentation. In realizing these costs for parking and the original intent to maintain the park-like nature, the proposal to integrate the new buildings into the earth was considered a successful conclusion to marrying all the constraints. To help relieve these parking requirements and the nature of the pockets of spaces and height differences, the proposal to amalgamate spaces (sports centre/conference facility and clubhouse) is introduced to assist in alleviating the parking demands as the bays will have the ability to be shared when positioned under a multitude of similar building uses.
SEPERATING PARKING & PEDESTRAIN – The park-like nature of the sports grounds has such a lush, free-flowing nature to it. This is preferably maintained is the driving factor behind maintaining pedestrian links to the inner areas of all the buildings. Vehicles will be able to access the site in the current location and only be able to drive around the outside of all spaces. They will be able to access both the hotel and Sports Centre building around the ring road. This also enhances the safety of people and their children when experiencing the park around the cricket pitches. A very accentuated driving concept in linking all the buildings with a circular pedestrian route around the cricket pitches is proposed and intends to link each outside space to each building into a single outside piazza-style space. The link in outside space between the hotel and Cricket clubhouse in particular, where there will be an activity link between lodging of players within the hotel and the link to the clubhouse and sports centre. Architecture is so often more about the space between buildings and this area in particular stresses the importance of the value of the spaces and the importance of them adjoining each other for the hotel and sports centre to compliment each other in their position next to each other.
Is also vital and the incentive behind a single access perimeter ring road is that cars are more easily controlled when kept along a singular route in and out of the spaces. Instead of river-like tributaries breaking up into different road routes through to all the buildings. FLEXIBILITY – also forms part of the nature of the proposed building locations and each building has the option to be re-positioned in their footprint locations. Whilst the restaurant is positioned in the south-east corner of the site, this location also has the option to exist as offices. The proposed hotel position also has the office to be presented as the location for offices and visa versa in the proposed office location. The Sports Centre and conference facility with the Clubhouse and flexible offices are most suitably located in between the cricket pitches on the west where basement parking can face highway views and the amount of parking is well accommodated with the most amount of available Town Planning area relative to all other sites. The existing Clubhouse location also offers the best clue as to its most suitable position and in capitalizing in the best mountain and cricket views over the grounds.
To Fabio Venturi of Terramanzi (Sustainable Energy Consultant) and Nik Moroff & Patrick Hut (Moroff & Kuhne Structural Engineers) for their invaluable insight and involvement during the design process.