From the beginning, V&A Waterfront had a clear aim to prioritise sustainability in all aspects of the building’s design. We aimed to create an innovative office building that accelerates the transition to net zero in South Africa.

The goal was to use first principles design to maximise human comfort, all within a low energy framework, to redefine what a great office could be by delivering more with less. We collaborated with local communities for the supply chain, thereby pushing the boundaries of a sustainable design.

In collaboration V&A Waterfront and StudioMAS, we pushed the boundaries of global green building design. The integrated and collaborative design process was based on foundational principles of sustainable design. Design decisions were progressively quantified via modelling, including extensive modelling of the various building systems to justify and validate a mixed-mode HVAC system based on natural ventilation supplemented by a thermally activated building structures (TABS). With its alternating timber and glazed panels, The Ridge’s visually striking façade is the first of its kind in South Africa. This façade allows for a high level of daylight and thermal control, maximising comfort and improving the building’s energy performance.

Owing to its design, the building is able to reduce its annual carbon emissions by 82%. The Ridge achieved a 6-star rating – the highest possible classification – from the Green Building Council of South Africa and was awarded Best Sustainable Building by the World Architecture News (WAN). The overall design reduced the amount of direct sunlight entering the building, which means that the internal spaces can prioritise natural ventilation over air conditioning, while still enabling its users to remain comfortable. The cross-laminated timber façade was the largest use of that material on a commercial scale in South Africa, which required extensive market engagement and enabled transformation of the sector.

Many of the concepts, technologies and materials used in the design and construction of The Ridge are pioneering instances of their use in South Africa, particularly at the scale of this project and in a high-end commercial space. This is an exciting new development for the V&A Waterfront, which embeds sustainable development principles through integrated design thinking wherever possible.

Façade engineering and design

The site – previously a car park – is orientated on a diagonal away from the ideal north–south orientation. While the east–west building orientation maximised the site’s development area, this arrangement was not favourable from a heat gain perspective. To counteract this, we proposed to ‘fold’ the façade in a series of zigzags, a solution enthusiastically embraced by studioMAS as they developed the building’s form. This allowed the orientation of individual facets to be optimised, with the glazed elements positioned facing either north or south. 

The timber façade was designed to be robust, and comprises locally sourced, solid, self-supporting cross laminated timber (CLT) panels, covered by timber cladding installed over a breathable membrane. This minimised heat load from solar gains by preventing lower-angle sun from the east or west entering the building. This solution admits daylight and maintains stunning views of Cape Town. 

On the external façade, manually operated windows give users control of the building’s temperature. Compared with fully air-conditioned buildings, people are more tolerant of temperature variations when they can control window operation. The design allows users to let in fresh air to circulate across each floor or to close the windows to suit their own comfort levels.

Mechanical engineering

Cape Town’s relatively mild climate is ideally suited to using natural ventilation for cooling. Our goal was to maximise the periods where the building could function in this manner, but this can be highly complex for a structure of this scale.

The thermally activated building structures (TABS) stabilise the temperature inside the building, smoothing the peaks between hot and cold. Chilled water is circulated through pipes that are embedded into the concrete floor slabs to provide radiant cooling to the office space. This is more energy-efficient for cooling compared with a ducted air system and means the building can rely on natural ventilation and TABS. 

With the internal design criteria being based on user comfort as opposed to strictly air temperature, it is designed to operate in natural ventilation mode for up to 81% of the year, and the fully fitted-out building is expected to save 64% in energy when compared to a similar property of the same size and orientation. Not only is this more efficient and more comfortable for users, but the openable windows provide occupant control and a direct connection to the broader V&A Waterfront location and its scenic views.

The design’s combination of mechanical air conditioning equipment, passive cooling technologies, and natural ventilation minimises energy consumption while prioritising occupant comfort.

Building services engineering

Our team worked to challenge traditional expectations for office space design by working together from project’s inception to identify what makes an environment comfortable. The mixed-mode design is reliant on how occupants operate the building to control their comfort, and thereby reduce energy use. It is through influencing occupants’ behaviour and empowering them to control their environment most effectively that the design intent is achieved.
In support of this, the building design includes a traffic light system that prompts occupants when to open windows for extra ventilation, improving air flow within the building.

We provided a higher level of training to The Ridge’s facility managers team than is the local industry norm and developed a comprehensive user guide for the building’s occupants. This explained how the building works to ensure they can reduce operational carbon by using its spaces efficiently day-to-day.

Building design

Given the task by the V&A Waterfront of creating a commercial property in Cape Town that pushed the boundaries of sustainable design, Arup, working with architects studioMAS, shaped a building response that accelerates the transition to net zero in South Africa. Close collaboration between the architects and Arup was key to the buildings low-energy design, with sustainable principles at the centre of each design decision. This ‘first principles’ approach embodied during the early design stages enabled the high performance design to be delivered without significant additional cost. A key feature of the success was the integrated design approach – where Arup delivered thirteen distinct disciplines as a single integrated service. 

The building is supplied with harvested rainwater and treated greywater, which is used for flushing toilets and watering greenery. This approach has reduced its potable water consumption by 50%.

We integrated approximately 14,000 ecobricks into the design to help reduce concrete and embodied carbon across the building. Sourced from a community project, each ecobrick is made of a 2L plastic bottle, filled with used single-use non-recyclable plastic compounded by hand.

The ecobricks have filled 450mm deep voids in the toilet cores adjacent to the access floors, locked 5.5 tonnes of plastic into the building and displaced approximately 24,000 litres of concrete, while creating an income opportunity for local people.

Fire engineering

The building’s performance-based fire design was instrumental to making the project vision possible. The number of protected stairs was chosen through fire and smoke modelling using computational fluid dynamics (CFD) and dynamic egress modelling. This design solution not only increases the building’s fire safety, but also increased its lettable area by minimising the space used by its stairs. In doing so, the fire design helped to improve the building’s cost efficiency. 

Building physics

Our building physics experts used a variety of tools to analyse the building’s facade and internal spaces to guide and validate design decisions. The result was an integrated design solution that reduces energy demand by 78%.  

Our team prioritised occupant well-being, ensuring that natural light and temperature were harmoniously balanced. The four-storey-high atrium is used as a chimney, pulling fresh air through from openable windows in the façade, across the office spaces and out through the atrium’s roof lights. Using the atrium as one of the building’s systems in this manner significantly enhances the effectiveness of its natural ventilation, making it possible to ventilate the full extent of the floor plates. This enables the design to strike the balance between occupant well-being and energy efficiency. 

Building information modelling

The project team used BIM360 as their digital collaboration platform, and carried out modelling in accordance with ISO 19650, ahead of the market norm in South Africa. Virtual contractor coordination sessions with the 3D model enabled contractors to pinpoint areas of concern for discussion. This virtual design and contracting team coordination resulted in the resolution of potential issues such as clashing services before they arose on site. The visual mechanism facilitated planning and programming of interfacing installations and saved time both on site and in the office.