South Africa’s first six-star Green Star office: Balwin’s green triumph

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Its corporate head office at 105 Corlett Drive in Johannesburg recently earned an ‘As Built’ Six-Star Green Star rating, the highest for any office building in South Africa.

Balwin chief executive, Steve Brookes explained: “Developed by the GBCSA, the ‘As Built’ Green Star rating measures the actual performance and attributes of the building against the original design objectives. This differs from the traditional Green Star rating, that measures design objectives only.”

To achieve an ‘As Built’ Six Star Green rating, every element of the building needs to be considered, including its design and layout, the materials used, energy and water consumption, energy generation, impact on the surrounding environment and the plants used in and around the building.

Added Brookes: “The ‘As Built’ Green Star tool works on a points-based system, where points are awarded under several categories. In order to receive a rating a certain number of points need to be achieved. In the case of a Six-Star Green Star rating – which is the highest – a minimum 75 points are required.

“We are very proud of 105 Corlett Drive achieving 82 points, which not only exceeded the ‘As Built’ Six Star Green Star rating but is also the highest score received for an ‘As Built’ office rating ever.”

Unprecedented Green ratings

The landmark asset on the corner of Corlett and the M1 highway opposite Melrose Arch was acquired by Balwin in 2022. The developer extensively refurbished the building, increasing its gross lettable area to approximately 7,609m² and retrofitting extensive green features

The Six-Star Green Star ‘As Built’ rating marks the fifth sustainability rating since the refurbishment and retrofitting of the development, which includes a Six-Star Green Star rating for design, Net Zero Carbon Level 1 modelled and Level 1 measured ratings, a Design rating, Construction rating and a Net Zero Waste Level 1 rating.

“The Net Zero waste is a unique rating which has not been achieved for a retrofit of this scale before. This rating is achieved by diverting all waste from the construction process away from landfill,” said Matthew Whalley, managing director of Balwin Energy.

In addition to a carbon neutral footprint for the based building, the retrofit resulted in significant cost savings for Balwin and other tenants in the building, in line with the ‘As-Built’ rating.

A large roof and carport mounted solar-panel array offsets approximately 40-50% of the building’s energy consumption in addition to ensuring consistent supply. In addition, a super capacitor minimises the reliance on generator back-up.

Rainwater is harvested, minimising the use of potable water for irrigation, while low-flow water fitting throughout the building lessens the reliance on municipal water.

Demand drives sustainability

The location of 105 Corlett Drive and proven sustainability features resulted in strong demand from tenants seeking a more environmentally friendly working environment, with the asset fully occupied.

Retrofitting a building of this scale to the highest green-rated standards is not without its challenges, however.

Whalley explains that the large open floor plan in particular posed a challenge from a lighting point of view. “We had to ensure that we zone these areas correctly for compliance and to ensure that we aren’t using lights in a space unnecessarily. In addition, we had to ensure that the parking areas provide sufficient space and facilities for electric vehicles.”

Brookes said that the corporate head office’s ‘As Built’ Six Star Green Star rating aligns with his commitment to environmentally friendly developments.

The group is the largest developer of IFC Edge and Edge Advanced apartments in the world, with a considerable number of apartments IFC Edge Advanced certified. In addition, Balwin recently launched its 12th carbon-neutral lifestyle centre.

Leveraging the group’s green building methods to the benefit of its homebuyers, Brookes pioneered Balwin’s Green Bonds, negotiating discounts of between 0.25% and 0.75% on homebuyers' bonds from the larger financiers, based on the environmentally friendly design and lower carbon footprint of the developments.

This initiative has saved homebuyers a combined R80m over a 20-year bond in the past financial year alone.