📸by the City of Cape Town, EBESA and Johan Lourens
Cape Town City’s Executive Mayor, Geordin Hill-Lewis addressed a launch event in June to showcase the City’s investment in a state-of-the-art new green sustainable centre in the Helderberg.
The Helderberg Environmental Centre is a success story of how alternative construction methods and sustainable design thinking can be achieved.
The setting of the reserve on the slopes of the Helderberg, overlooking False Bay, 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.
According to Hill-Lewis: “‘The new Helderberg Environmental Centre is truly a magnificent building and provides the perfect setting for the various environmental education programmes the City’s nature reserves offer schools and interest groups.
“This centre provides us with a practical example of what a green City facility can look like. The project has proved just how beneficial implementing green construction practices can be, especially if one considers the amount of semi-skilled EPWP job opportunities that were created to assist with the material selection and specific green construction techniques”.
Project architect Jacqueline Stow of EBESA Architects, says that the purpose of the new centre is to accommodate the current staff capacity while also providing additional complementary services, including a multipurpose space and two-tier roof garden overlooking the existing stage area to the north.
“In essence, the project brief specified regenerative design methods and required the use of recycled material, including reinforced tyre and rammed-earth technology, as load bearing walls within the building envelope and also the use of eco-brick as internal decorative dividing walls. There is a strong emphasis on passive design interventions to achieve thermal performance during seasonal periods.
“In order to achieve these sustainable goals, we combined conventional and unconventional proven green technology solutions to reduce the carbon emission of the building and encourage a renewable resource thinking approach to the project,” she adds.
The overall project budget was R20.8million and ultimately, practical completion was reached on 1 Dec 2021.
The three wall types at the Centre showcase the principle of carbon burying, according to the City’s planners. The materials that would otherwise become a burden in a landfill were reused and repurposed and given a new life.
This new facility now serves as a carbon sink by sequestering waste. The idea of repurposing and upcycling materials allows this centre to speak to sustainability. In addition, approximately 176 cubic metres of earth and recycled building rubble were used for the rammed earth walls and foundations as well.
Water treatment system
The integrated water treatment system serves the new facility and solves the burden of the waste water generated by the existing facilities. Waste water from the new facility; the nearby restaurant; ablutions; the visitor’s centre and rain water from the new facility are captured and sent to the underground black water treatment system.
The black water treatment system takes waste water and passes it 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.
TO BUILD spoke to Jacqueline Stow of EBESA Architects to find out more…
The building has a very unconventional look. Please explain how the various elements of regenerative design fit together to make this building deliver comfort inside, low embodied EC/EE and also low operational energy usage.
The building is nestled within the existing embankment for two main reasons as a practical solution to the position of the building in relation to the existing buildings found on site. It also embraced the green building principals of using the earth’s natural cooling properties once the building was completed. This reduces the need for heating and cooling within the building lowering its energy consumption.
Please explain the role of the rooftop garden. How are the plants irrigated?
The rooftop garden was designed for a few reasons; thermal comfort of the internal space, access to the roof space for educational purposes and to integrate the building with its natural surroundings. Drip irrigation is used.
We note that an active HVAC system was installed in addition to the passive design methods employed. Can you tell us more about its purpose and design?
The HVAC system was installed and designed for extreme temperature conditions experienced in the Helderberg area, and specifically for the large open space accommodating large school groups. We allowed for cassette units in the offices and boardrooms too. Having said that, we did not target a specific indoor temperature during the design phase.
The tyre wall against the earth embankment as well as the rammed earth wall to the external open facade of the building maintain very good ambient internal climate control. There was no need to dehumidify the internal spaces.
Has there been any operational feedback about the centre through winter?
The building performed very well during winter and the public are very impressed with the building. All that visit it loves the uniqueness of it.
Are there any professionals or suppliers on the project that you would like to acknowledge and what were their contributions?
I would like to acknowledge the City of Cape Town for daring to spearhead buildings like this for the public realm.
About the climate control approaches
Stow says that a passive design intervention is a “second tier overlay component to the project” realised through the introduction of active and passive solar energy storage and heating systems.
“Through these passive design considerations, we were able to use the thermal performance material to control the ambient temperature internally, the recycling of greywater and rainwater harvesting to minimise the end-user energy consumption, fresh water usage and also processing of solid waste generated,” she comments.
A Daikin VRV heat recovery system was specified and installed to air-condition the office spaces providing simultaneous heating and cooling to the areas where required, to provide the following features:
- VRV heat recovery system with VRT (Variable Refrigerant Temperature control function) allows automatic adjustment of the refrigerant temperature according to the internal building requirements and outdoor weather conditions. This is the most energy efficient solution for the Heldeberg project.
- VAM – Heat Recovery ventilation was chosen as an energy saving solution to provide heating, cooling and moisture recovery to the fresh air supply to the building. This also allows free cooling operation when the indoor temperature is below the set point inside the building.
According to the City, the design of this holistic and sustainable facility considered a number of components such as:
- Thermal impact
- Ground, waste and stormwater impact
- Light pollution
- Reducing carbon emissions
To demonstrate alternative construction methods, the design showcased three approaches where waste was used in the wall construction. The concept for the enclosure is based on two curved walls, one fitting into the other.
Client: City of Cape Town
Architect: EBESA Architects
Quantity Surveyor: Narker & Associates
Civil, Structural, Electrical & Mechanical Engineers: NWE Consulting Engineers
Health & Safety Consultant: Frontline Sheq
Environmental Consultant: Sollito
Landscape Architect: Viridian Consulting
Project Manager: Goal Zero Projects
Main Contractor: The Construction Co.