The Ridge: The whole is greater than the sum of its parts

By V&A Waterfront

Cape Town’s newest 6-star Green Star design awarded commercial building, the Ridge in the V&A Waterfront, has recently opened and the Cape Town office of its tenant, Deloitte South Africa, is trading from inside its unique spaces.

The Ridge deploys some of the most advanced sustainable building technology available globally, as well as original blue-sky thinking. It was borne from the V&A Waterfront’s vision to set new standards for the future of commercial office buildings. The final design was the result of the creative inputs of the project’s multi-disciplinary design team, which worked closely together.

Over the past decade, the Waterfront has blazed a trail of sustainable development, rewarded with Green Star accreditations by the Green Building Council of South Africa. Individual buildings include the Allan Gray building at No.1 Silo, the Watershed and No.5 Silo, all 6 Green Star buildings plus several other firsts which include former Grain Silo which became Zeitz MOCAA (Museum of Contemporary Art Africa) and the boutique Silo Hotel, as well as No.6 Silo incorporating the Radisson Red (the first 5-star Green Star hotel).

David Green, CEO of the V&A Waterfront, explains that this project showcases the capabilities of the Waterfront as a developer in providing custom designed office or mixed-use accommodation to the highest standard in line with the needs of the customer.

“The Ridge and our other developments provide a working example as to how it can be done for companies that are looking to the future of their businesses in a sustainable way with a focus on both environmental performance and the greatest asset a company has: its people. This development represents the confidence that our company and its shareholders have in the future of Cape Town as a destination and our confidence in South Africa itself”, he says.

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Vusi Nondo, the executive manager for development at the V&A Waterfront explains that the Ridge has been an important milestone for the Waterfront in its rollout of bespoke office space, mixed use, and retail offerings.

“It has been said that working from an office post-Covid-19 will never be the same again – worldwide. Of course, that is true, but long prior to the pandemic, the Waterfront development team identified a healthy office space that looks after the wellness of employees as being of paramount importance to any business. Armed with a development approach we consider as ‘our normal’, we have implemented people-centred innovations in all our bespoke developments. These promote a healthy work environment, help in combating sick building syndrome and promote low carbon modes of transport. These include pedestrian footpaths, bicycle routes/parks, outdoor greened relaxation areas and even food gardens”, he says.

Unique mixed-mode interior climate control system

The Waterfont’s development director and project leader for the Ridge, Mark Noble, explains why the office work experience is exceptional and how the Ridge’s bespoke features set it apart from other commercial buildings.

Noble says, “We designed the Ridge to be a world-class living, breathing building by incorporating a number of standout features, some of which are firsts for South Africa.”

Some of these features:

Air quality: The building operates on mixed mode interior climate control system, which includes Natural ventilation, which significantly raises the indoor air quality and is controlled by the occupants. This means that office workers may open the windows to let in fresh air for up to 80% of the year round. An impressive atrium runs from ground to the third level of the building. Referred to as the ‘central street’, it helps to pull air through the building, in through the windows and out through the rooflights, while also bringing many other benefits to workers and visitors inside the building.

Minimal HVAC (air conditioning) usage: The building incorporates passive (non-energy consuming) temperature control mechanisms several of which are unique, a virtual sum of parts that leads to a greater whole.

The zigzag shaped engineered timber façade ingeniously orientates the glass windows towards the north or south, which prevents lower angle sun from the east or west from entering the office spaces. This provides natural daylight while reducing glare and patches of hot sunlight. This has a major impact in promoting both fresh air quality and the saving of energy.

Thermally Activated Building System Technology (TABS): TABS is installed into the soffits (ceilings) above the working areas of the building, and this cools the concrete structure by means of water circulating from the chiller and heat pumps on the roof. The cooler soffit hence cools the air below, which circulates around the workspace. TABS is another important contributor to the mixed mode climate control system at work inside the building.

“All these measures mean that people inside the building will experience steady indoor ambient temperatures which respond slowly to outdoor temperature variations. The mixed-mode system design aims for the building’s conventional air conditioning system to be active for only 20% of the year. This is in line with international standards such as WELL, in promoting occupant productivity and thermal comfort,” Noble adds.

This rendering shows how the Thermally Activated Building System (TABS) works, by cooling the concrete structure by means of water circulating from the chiller and heat pumps on the roof. The cooler soffit hence cools the air below, which circulates around the workspace. Image credit: ©Arup

The Ridge’s further sustainability features

Power: The building has a specific energy strategy. Passive energy efficient features are incorporated, to reduce base energy load. Active energy efficient designs include low-energy lighting systems. A solar array on the roof harvests additional power when the sun is shining. Ultimately, in the case of a grid failure, vital systems in the building are kept going by means of a standby generator.

Water resources: The building employs the normal low water flow devices in sympathy with Cape Town’s growing status as an arid city. Grey water and rainwater harvested from the roof is collected and reused for toilet flushing and irrigation.

Dematerialisation and recycling: The focus given by designers to dematerialisation, re-use and recycling is well documented, including the South African first-ever usage of ecobricks encapsulated within certain non-load bearing structural elements of the building.

Greening the interior: Within the Ridge, the natural environment is king. Green plants and a planted balcony for occupants are features of the design philosophy that incorporates greenery.

A team achieving a greater holistic concept

The façade on the top two floors of the building is constructed from locally sourced cross laminated mass timber together with the more standard glass and aluminium panels in a unitised system. This is a very significant feature.

“Using timber as both the structural façade element as well as the internal and external finish we believe is a genuine first for South Africa and one that has contributed significantly both to the overall architecture as well as reducing the overall carbon footprint of the building by 60 tonnes CO₂ (equivalent) from the atmosphere”, says Noble.

The Ridge also forms the hub of a broader mixed-use district of the Waterfront, called the Portswood District.

The Roof CHW system – This is a more holistic view of the roof plant, specifically the buffer tank and pipe network after being fully insulated by ULAG. Image credit: Arup

“We have a number of heritage houses that have been restored at the same time as the Ridge was under construction. These form part of the new district which will focus heavily on non-motorised mobility. While the district is envisaged as a commercial node, we are constructing public footpaths and a bicycle route will navigate the area. The area will offer shady retreats, a Petersham Nurseries style cafe made solely from waste material from the V&A including a feature glass bottle wall (designed by PE based architect Kevin Kimwelle), a vegetable garden and the security of being within the Waterfront. We see this new district as a kind of secret garden with a high density of green open spaces and trees creating an environment that is truly unique in an inner-city location. With the opening of the Ridge at the Portswood District, it is now possible to navigate from this new commercial district, via the Watershed and beyond to our established retail and mixed-use property assets, including Victoria Wharf, the Clock Tower district, the Silo district or even Granger Bay,” Noble adds.

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“Our impact on the environment was a key consideration throughout the building project and therefore the 6-Star rating is an incredible achievement. Achieving certification means that we have succeeded, through collaboration with the development team, in building a high-performing, productive workplace that is healthier for our people and the environment,” says Wayne Megaw, Operations Leader at Deloitte Africa.

He continues, “The interior design further ensures that the office becomes a place to work more dynamically through offering the right kind of working space available at the right time. The Ridge offers a range of different working activities and styles with spaces that can fuel creativity and will ultimately generate more collaborations across our multiple business units. There are no private offices for any staff with hot desking being embraced to support openness, chance interactions, teamwork, and increased collaboration. The office promises improved efficiency, integration and sustainability which is good for our business, our people, our clients and the environment, as well as our long-term capacity needs.”

Unique engineered features

Tessa Brunette, the lead project engineer from Arup says, “Together with the buildings’ intrinsic thermal mass, the façade is the most important ‘machine’ (controlling indoor environment) in the building. We reached our design response using first principles, in close collaboration with studioMAS, the architects.

“These design responses were then tested and refined by using advanced computer modelling methods. These included the testing of different glazing types, orientations, and shading types. Thus, we identified the optimum combination of orientation vs shading vs glazing type.

“Through an iterative process with many stages of analysis, modelling and interpretation initial modelling, the various options were refined to assess which combinations worked best in conjunction with the architecture and budget.

“Modelling confirmed that the zigzag (pleated) façade that we adopted for building levels 2 and 3 performs as well as a straight deeply shaded façade and allows for more glazing without external shading devices that could obstruct views to the outside and reduce the amount of internal natural light.

“So, the design significantly reduces the amount of direct sunlight entering the building, which in turn means that the internal spaces can largely rely on the mixed mode system and not need air conditioning to remain comfortable.

The building is designed to be as comfortable as possible without needing air conditioning to heat or cool. Occupants can control their personal comfort by adding or removing outer layers of clothing. If that is not enough, the controls can be adjusted to suit what the user prefers.”

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The TABS operates continuously throughout warmer months, cooling the internal environment using chilled water circulating through the floor slabs. This complements the operation of the natural ventilation system and HVAC, meaning that the building’s possible use of fresh air ventilation rises from 60% to 80% of the year.

It is all done on a controlled basis. Traffic lights installed around the building perimeter indicate to the occupants when they should open and close the windows, based on outside conditions.

When the windows are open, the active ventilation system is switched off. When the weather outside is not suitable for natural ventilation, the building management system (BMS) activates HVAC (air conditioning), provided that the windows have been manually closed.

Air from the HVAC system, when switched on by the BMS, enters the office spaces via a low energy usage displacement ventilation system via air grilles that are in the floor.

Special custom-designed acoustic panels are suspended underneath the exposed slabs to provide appropriate levels of sound absorption for a comfortable work environment, whilst leaving sufficient exposed thermal mass for the TABS to provide benefit to the occupants.

Architectural criteria

Sean Mahoney, the Ridge project lead architect, Studio MAS, says their role as the architect is to combine the logic and practicalities of engineering with the creative arts. “I think of the climate control systems in use at the Ridge as the (Toyota) Prius of the built environment – a veritable hybrid,” he says.

This was a collaborative process with Arup best illustrated on the Ridge by the zigzag timber façade and the ‘central street’ with its roof light drums. Both these design elements have a strong engineering and design rationale backing them up, but at the same time managed to create beauty and joy out of them. They are key to the building’s identity and aesthetic and create memorable experiences. These include natural light, natural timber in the case of façade, wonderful views out of the windows, connection with the outdoors and identity.

According to Mahoney a major design requirement was the building having an operable façade. This is achieved via the unique pleated (zigzag) façade concept, which fills a vital function from an engineering perspective. He admits that inspiration for the pleated façade came in part from doing origami at his desk in the office. “Triangles as per origami shapes take on a special meaning in this building, as borne out by the façade design and several other design elements. But ultimately the pleated façade is driven by logic:  it creates a north-south orientation for the façade, meaning that you can control the effect of direct sunlight.”

“Timelessness in architecture is something that many designers strive for. The timber façade itself will evolve and keep functioning over the years, changing colour as it weathers, developing a patina, and making the building stand out as unique,” he adds.

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Achieving its 6-star Green Star Design Rating

Lisa Reynolds, CEO of the Green Building Council of South Africa (GBCSA), commends the V&A Waterfront and the entire professional team on another iconic 6-star Green Star certified building within the Waterfront precinct.

“The Ridge represents the V&A’s commitments to world class sustainability leadership as well as showcasing local built environment professional talent capable of delivering innovative sustainable design,” says Reynolds. “Green buildings like the Ridge help to inspire a built environment in which both people and planet thrive,” she adds.

Georgina Smit, Head of Technical at the GBCSA explains that a 6-star Green Star Design rating at the project design stage represents an intent to achieve a sustainability performance level that equates to world leadership, exceeding South African excellence (5-star) and industry best practice (4-star).

“Six-star ratings are unusual in South Africa and is not an easy achievement for a design rating. Only nine other offices have achieved this accolade to date, either through our Design or As Built rating, or both, since 2010. It involves a committed client, a dedicated professional team and an integrated design approach by all,” Smit adds.

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