Helderberg Environmental Centre
Size: 1150 m²
Cost: R 20 758 780
Completed: 2021
Location: Somerset West, Cape Town, Western Cape
Located on the slopes of the Helderberg Mountain overlooking the beautiful False Bay, the new multi-purpose, state-of-the-art Helderberg Environmental Centre offers an inviting space for biodiversity education. The client’s initial design concept was spearheaded by Ashley Hemraj, Senior Architect of the City of Cape Town, to advance sustainable green architecture underpinned by sound passive design principles that are resource and energy-efficient and environmentally responsible. Let’s see how the project unfolded…
Brief and design concept
Ebesa Architects’ appointment as the JV project team was to design and construct a new educational facility for CoCT (City of Cape Town) at Helderberg Nature Reserve. The beautiful setting of the reserve makes it an ideal location to teach communities in and around Somerset West about the Western Cape’s plant and animal kingdom and our impact on it. As such, the staff at the reserve identified the need for an environmental education centre where school groups and visitors can be accommodated. The new building needed to house the current staff capacity as well as additional services, including a multi-purpose space and a two-tier roof garden overlooking the existing stage area to the north.
In essence, the project brief required the extensive use of recycled materials, such as reinforced tyre and rammed-earth technology for load-bearing walls (forming the building envelope), and the use of ecobricks for internal decorative dividing walls. Additionally, the project necessitated a strong emphasis on passive design interventions to achieve thermal performance during seasonal periods. To fulfil these sustainable goals, proven conventional and unconventional green technology solutions were combined to reduce the carbon emissions of the building and to encourage an approach that is rooted in renewable resources.
Inspired by ‘biophilic design principles’ that encourage human engagement with the natural environment ‘through the interaction of direct nature, indirect nature, and space and place conditions,’ the building aimed to form a nexus between humans and the environment. This is evident in the design form, the orientation of the building, the use of natural material and the expression thereof, the harnessing of natural sunlight, and passive ventilation, which filters through the internal spaces and roof garden.
The civil, structural, electrical, and mechanical engineers supported these innovative design objectives by providing hands-on, ecologically-sensitive services. The ‘passive design principles’ approach is a second-tier, overlay component to the project, which introduced both active and passive solar energy storage and heating systems. This includes the use of thermal performance material to control the ambient temperature internally; the recycling of greywater and harvesting of rainwater to minimise end-user energy consumption; the management of freshwater usage; and processing of solid waste. The existing topography and natural surrounding landscape elements were also preserved to maintain the original character and essence of the chosen site.
The Helderberg Environmental Centre will become a flagship project that embodies and promotes green design solutions in line with the framework and goals of SALGA, GBCSA, and ICLEI Africa. The building not only demonstrates the practical intervention of alternative sustainable technology, but also facilitates the transferral of critical skills and economic opportunities through the engagement of local communities and artisans. For example, 32 EPWP jobs were created for people from local communities who gained sustainable building skills.
Site and locality diagrams
Situated in a spot opposite to the existing heritage building, the site is just of the access road and the road that leads to the main entrance connecting to Verster Avenue, which forms a part of the wider Helderberg Nature Reserve precinct.
Before building commenced on the new educational facility, the nature reserve already sported various supplementary structures, including a heritage building, café and resource centre, male and female restrooms, a bird lookout post, and a concert stage. The remaining portion of the 403 hectares utilises the locality in the most scenic of ways: boardwalk trails meander around the slopes of Helderberg West Peak, leading visitors to isolated seating areas overlooking the region’s indigenous flora and fauna, and the bird sanctuary beyond.
Unpacking the design
Position and orientation
The building was positioned in relation to the mountain, stage, embankment, and the current information centre, which meant the placement of the building was a subject of major consideration. Once the position, shape, orientation of the building was determined, and the delicate play between the aforementioned constraints was established, the design team shifted their focus to selecting the materials for the new building.
Materials
Aided by the Natural Building Collective, the team workshopped the selection and implementation of alternative building materials and were able to find practical solutions in implementing these materials into the building design, and eventually into the construction process. The outer layer of the building envelope, which was encroaching into the embankment, needed to be waterproofed extensively. This posed quite the challenge as the wall was constructed out of tyres and cobb. In order to address the matter, the walls were first layered with plaster to secure the cob and to provide a substrate to apply bitumen layers. This was followed by an additional layer of bubble drainage, sand, and then, finally, a French drain before the embankment wall was re-established.
The tyre wall started at a base width of 800mm that narrowed towards 400mm at the top. The outer rammed earth wall was particularly challenging, as it had to house the structural columns needed to support the coffered slab roof, enabling the design team to have the hall space free of any internal columns that could potentially interfere with the earth-ramming process. Local material was used for the rammed earth, as well as two different shades to create a colour movement within the wall. The wall was 600mm thick and was coated with a protective layer to reduce the impact of weather over time. Lastly, a Bedouin tent structure was designed to clip on and off the building so that the client can use it for outdoor functions.
Roof
The roof structure was designed to span the entire hall area and to allow both people and plants on top. This was achieved by using a coffer slab on the upper roof structure. Balustrades were designed to protect the people on the roof, but were not placed on the outer edge so as to minimise the visual impact. We wanted lookout points where people could go all the way to the edge of the building, which is why we placed glass balustrades there. The garden on the roof structure aids in the thermal comfort of the building and includes low-growing indigenous planting with drip irrigation.
Sustainable systems and principles
Apart from the sessions hosted inside the facility, the building itself was also designed to educate its visitors on its function and construction process. The ramp on the side of the building leads people around the structure to engage all their senses as they take in the full visuals of the building. From the exposed tyres and rammed-earth walls that beckon a visitor’s touch as they move around the centre, to the services placed on the lower-roof structure, there is plenty to admire.
The three different wall types showcase the principle of carbon burying: the inner curved wall and foundations were constructed using rammed earth and repurposed building rubble, and the outer curved retaining wall was constructed from repurposed tyres. This massively reduced the amount of cement needed for construction (cement has one of the highest carbon footprints of all building materials). A total of 830 recycled truck tyres were used for the tyre wall, which is approximately 40 metres long and 3.4 metres high. Building rubble, sand from other construction sites, and ecobricks (made from plastic bottles filled and compacted with plastic waste), were used to fill the tyres and the internal wall. Natural cob — an environmentally-friendly plaster mix — was also used to cover the ecobricks instead of conventional cement-based plaster. In addition, approximately 176 cubic metres of earth and recycled building rubble were used for the rammed earth walls and foundations. Materials that would otherwise have become a burden in a landfill were reused and given a new life. The idea of repurposing and upcycling materials allows this centre to speak to sustainability and waste sequestration. The building is also a carbon sink, meaning it saves and absorbs more carbon than it uses.
A Maskam system creates a closed system for water and wastewater usage, coupled with water harvesting to supplement the water supply. Wastewater and rainwater from the new and existing facilities are captured and sent to the underground blackwater treatment system. There, wastewater passes through a four-chamber process before being stored in storage tanks for the flushing of toilets in the new facility and existing ablution blocks. This ensures minimum water usage and zero water wastage. The treatment system makes use of bacteria and microorganisms to break down solids and treat the wastewater — a process that mimics nature without releasing harmful nitrates into the atmosphere. Additionally, the centre is fitted with a solar photovoltaic system to generate its own electricity. As a result, the savings in terms of electricity costs and carbon emissions are significant.
Interiors
By minimising the use of finishes, the interior of the building was kept functional and environmentally conscious. Polished concrete floors were used throughout, and reclaimed materials were used for cladding, doors, and windows. Ecophon panels were used in the hall and boardroom for acoustic treatment.
Roof lights and clerestory windows were used to bring in light from a higher level, and the round windows used in the office areas were constructed using civil drainage pipes penetrating the tyre wall construction. The front area of the hall was treated as a glass façade that could completely be opened to the outside, taking full advantage of the beautiful view and outside function area.
Overall, the construction process took 11 months before the Helderberg Environmental Centre was ready to welcome visitors and school groups.
THE LANDSCAPE
Brief and location
Initially, Helderberg Nature Reserve was home to a small, existing visitor centre as well as a separate environmental education centre aimed mainly at school groups. However, the education centre was tucked away in a non-public part of the reserve, making it inaccessible to visitors. Therefore, a new vision for the reserve was to develop a combined visitor and environmental education centre to showcase green architecture.
The goal was to integrate the building into the landscape by using environmentally sustainable construction methods and materials. Viridian Consulting Landscape Architects assisted with positioning and orientating the building, strategically using the site’s scenic locale to create a unique sense of place. The building is oriented towards the lawn and stage, and opens itself up to the audience seating area, creating a backdrop and extension from where the summer concerts can be enjoyed in the evenings and over weekends. The new building’s position functionally relates to the space between the former centre, and has been nestled into the embankment. Another enhancement to the building includes a rooftop garden that has been designed to experience the concerts and enjoy the spectacular views of the surrounding mountains. Accessible for environmental education purposes, the rooftop also houses solar panels that supply electricity to the centre. The facility is a tangible extension of environmental learning, giving visitors a first-hand experience of the positive impact of sustainability-in-action.
Landscape design philosophy
The landscape architects sought to integrate a new and iconic structure into the landscape in timeless a way by creating the sense that the building is a part of the landscape, and not imposed on it. As such, the formation of an ‘integrated whole’ was key to the entire project.
Water and planting
In a similar vein, the planting and earthworks approach was also to settle the building into the landscape sustainably, using a locally indigenous planting palette. The roof garden has an artificial growing environment, which is why irrigation is crucial. Indigenous plants and succulents are irrigated with rainwater and recycled greywater.
The extensive, yet water-hungry, lawns that contribute to the site’s recreational value need a non-potable water source in order to meet its ongoing irrigation demand sustainably. The concert lawns are located on a natural drainage line with fairly high groundwater levels. The natural groundwater seepage had previously allowed the lawns to retain their active growth throughout the dry summer months. Therefore, the new building was positioned across this natural seepage line, and a subsoil drainage system has been used to divert the groundwater around the building to a constructed well point from where the water is automatically pumped into irrigation water-storage tanks.
The lawns, new planting, and roof garden all make use of this water source for irrigation. When the available water exceeds the irrigation demand, it overflows into a constructed drainage channel that diverts rainwater and overland flow away from the building into an unlined, constructed pond located on the natural drainage line. This results in the reinstatement of the natural groundwater seepage, maintaining groundwater conditions for the existing trees and vegetation established along the drainage line.
The pond has evolved into a year-round water feature, creating a habitat for a wider range of vegetation and fauna to be established close to the visitor centre. Timber decking walkways make the pond accessible to visitors and groups attending environmental education sessions. Plus, the placement of large sandstone boulders provides a place for visitors to rest or inch closer to the pond.
Original site elements
There were a couple of elements on the original site that had to be taken into account prior to the landscape design process. A number of indigenous trees (mostly Afrocarpus) planted by ‘Friends of the Helderberg Nature Reserve’ over many years obstructed the site of the new building. Viridian Consulting Landscape Architects applied for a permit to have them removed and, in exchange, a similar number of Cunonia capensis and Afrocarpus falcatus trees were planted in the reserve’s picnic and lawn areas. Additionally, initial funding for the project was established through the sale of pine trees for harvesting on the slopes of the reserve. Some of the harvested timber was also used in the building itself.
The existing natural drainage line and seepage (groundwater in the area) also had to be integrated into the design for irrigation and the creation of the pond. Lastly, the views of the mountain and orientation of the building also influenced the landscape design.
Hard and soft landscaping
Some of the hard landscaping elements included gabion retaining structures, retaining walls, and timber decking that helped to create the forecourt and landing areas around the building, and the timber pathways joining into existing timber elements, including on the rooftop garden.
Around the back of the building, stormwater channels were constructed from natural rock to absorb the flow off the embankment emptying into the constructed, natural soil pond. Paving and stairs are also present, speaking to the levels and flow around the building. Solar panels were installed on the rooftop garden to comply with the power demand. To avoid shading and obscuring the garden, the landscape architects also made their planting choices in light of the position and orientation of these panels.
Tolerant species were used for the soft landscaping as they can handle a wide range of extreme soil moisture conditions. The rooftop garden was planted with a variety of succulent species — a good choice considering that it would be hot and dry in summer and wet in winter. Geoplast (a specialised drainage layer) was used to successfully regulate the drainage on the roof garden. It consists of a cup-like drainage structure that creates mini reservoirs to hold water, increasing soil moisture holding capacity on the roof while still allowing free drainage to prevent waterlogging.
Maintenance and irrigation
Maintenance is being done by the Helderberg Nature Reserve’s on-site staff (City of Cape Town). Irrigation consists of a combination of sprayers and drip irrigation on the rooftop garden, using the recycled, captured groundwater, which is recycled into the tank system for the large lawn areas.
MEET THE TEAM
Client: City of Cape Town, specifically Nature Conservation and the Urban Planning and Design Department
Architect: Ebesa Architects
Landscape architect: Rene Maria Brett, Viridian Consulting Landscape Architects
Environmental consultant: Sillito Environmental Consultants
Landscape and irrigation contractor: Ezra Watson, Bantu Environmental Solutions
Principal agent: ENN JV
Quantity surveyor: Narker
Principal building contractor: The Construction Co.
Civil contractor: Regal Civils
Structural and mechanical engineer: NWE
HVAC installer: Khubanda
Electrical installer: Power Trust
PV solar installer: Current Automation
Paint contractor: First Class Painters
Specialist sub-contractor: Natural Building Collective
Rammed earth specialist sub-contractor: Simply Sustainable
Ceiling and bulkhead specialist sub-contractor: Ceil Wall
Occupational health and safety consultant: Frontline
