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Timber Facade Rises From Sustainability Ethos

By Staff writer

Driving down Dock Road in the direction of the Watershed at the V&A Waterfront nearing the One and Only hotel to the right, one cannot help notice the impressive and completely unique engineered timber pleated façade warmly cladding the Waterfront’s newest building which is currently under construction on the left. 

Incorporating cross-laminated timber (CLT), and various energy efficient building design elements, the Ridge’s new façade speaks to the sustainability ethos of the V&A Waterfront’s development vision. It may well become one of Cape Town’s most sustainable buildings.

In a nutshell, the new timber façade plays a very important part in a range of measures facilitating natural indoor temperature control and fresh air inside the building instead of conventional air conditioning (HVAC) for most days of the year. This yields not only savings in operating costs for heating and cooling, but also greatly benefits health, productivity and well-being of building users.

“Of great importance to the Waterfront’s Our Normal approach of using sustainable construction methods, the use of CLT in place of brick and concrete and saving the use of additional aluminium and glass on the façade has greatly reduced the Ridge’s carbon footprint.

“Structurally graded engineered timber as used in the production of our CLT come from sustainable plantations, mainly located within the Western Cape. In addition to the material being a net sequestrator of carbon dioxide from the atmosphere, timber sourced within the province minimises the transport carbon emission contribution also”, explains the Development Director at the V&A Waterfront, Mark Noble. For further information, refer to the V&A Waterfront Technical Fact Sheet.

Lead architect on the Ridge project, Sean Mahoney of Studio MAS Architecture and Urban Design, comments that timber is the most natural choice of walling material for a sustainability building such as the Ridge and utilises biophilic principles.  These strive to connect the occupants of a building with their natural environment, thereby achieving health, environmental, and economic benefits for building occupants.

“One of the key challenges was: ‘On a good day, can you open a window?’. Designing a suitable response to this and setting the building apart from the sealed glassed-in prevailing corporate standard, took our team on a 3-year path defining the Waterfront’s new normal standard. It’s something fresh and unique”, says Mahoney.

Tessa Brunette, lead engineering and façade consultant at Arup agrees: “The use of CLT is a large contributor to the green credentials of this building. The design reduces the amount of sunlight entering the building, meaning that the internal spaces can largely rely on natural ventilation and not air conditioning to remain comfortable.

In addition to an exterior timber ‘skin’, the interior walls where the façade has been applied will also be exposed CLT, giving the interior of the building a warm feel.

Mark Noble adds: “Increasingly, the negative effects of building in a sealed-in office space are becoming known worldwide. One of the more serious results of the way that humankind has built in the past is sick building syndrome (SBS.) SBS explains the onset of various illnesses among workers, absenteeism and poor morale among staff leading to a loss in productivity.  The Ridge strives to counteract this.

“This is part of the Waterfront’s Our Normal ethos, and it also meets the sustainability approach of our client, Deloitte”.

Why the zig-zag shape?

Mahoney says that a major design element hinged on the building having an operable façade. Hence, the unique pleated (zig-zag) façade consists of cross-laminated timber panels on one facet with high performance glass set into aluminium on the other side. Most of the glazed units contain custom-designed opening windows.

“This allows people working inside the building to have a degree of control over their environment/air quality by opting to open the window”, he says.

“Our pleated façade is driven by logic:  it creates a north-south- east-west orientation for the façade, meaning that you can control the effect of direct sunlight and thereby the indoor temperature”, Mahoney continues. <Further information is available in the Technical Fact Sheet>.

“The glazed and timber sawtooth façade is prefabricated, enabling high quality assembly and fast installation, and it is machined to very accurate tolerances. It’s strong but lightweight and enhances the standout character of this building as a prestigious corporate headquarters for the client, Deloitte”, adds Brunette.

What is CLT?

An engineered timber, first developed and used in Germany in the early 90’s, Cross-laminated timber (CLT) is regarded as a rising star among natural construction materials. Made into panels and used in mass timber construction projects, it is manufactured to specifications issued by the relevant authorities. In South Africa it is fairly rare. The structurally graded timber ply runs at ninety degree directions along each layer, providing structural strength in both linear directions. The CLT at the Ridge has five layers.

This board is superior to conventional laminated timber or glulam and in SA there is only one manufacturer.

At the Ridge, 960 m2 of CLT timber panels were used, weighing 36 tonnes. They were fabricated at XLAM in Retreat, a dedicated factory in Cape Town and currently the only manufacturer in SA.

According to Jamie Smily of XLAM, the SA Bureau of Standards has recently developed a standard for cross-laminated timber, recognising it as an approved building material in South Africa.

“Our timber is sourced from sustainable plantations, mainly in the Western Cape and we receive it as rough-cut boards from the timber mills. The CLT as used at the Waterfront is long-lasting, with a service life of 50 years plus”, adds Smily.

CO2 considerations

“Due to sustainable forestry operations being used to grow the timber, we estimate that our usage of 36 tonnes of CLT on the project has removed 60 tonnes of CO2 (equivalent) from the atmosphere, calculated using the Carbon and Energy Index by the University of Bath” says Noble.

“In addition, our engineers have calculated that 354 tonnes of CO2 has been saved by using timber on this project, in lieu of conventional materials”. <Refer to Technical Fact Sheet>.

CLT is increasingly being used for tall buildings globally

Opened in mid-March 2019, the Mjøstårnet/ Mjøsa Tower in Brumunddal near Oslo, Norway, reaching 85.4 metres, is currently the world’s tallest engineered timber building. The 18-storey tower is made from lightweight prefabricated materials, consisting of glulam, CLT and laminated veneer timber.

Another famous structural timber-containing commercial building under construction is the huge Google London Headquarters at King’s Cross. This building is designed by the Heatherwick Studio, which incidentally was the visionary architect behind the redevelopment of the V&A Grain Silo into the Zeitz MOCAA Museum of Art and SILO Hotel.

Façade design, manufacture and installation team

Developer: V&A Waterfront

Architect: Studio MAS

Engineering/Consultants: ARUP

CLT fabricator: XLAM

Façade – Aluminium & Glass Fabricator and Erector: Geustyn & Horak

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