In 2019, Growthpoint Properties’ iconic 144 Oxford Street project in Rosebank, Johannesburg, was awarded a 5-Star Green Star Office Design rating by the Green Building Council of South Africa (GBCSA). Recently, the development also secured a 5-Star Green Star Office As Built rating.

Sustained value has long been a non-negotiable, integral part of Growthpoint Properties’ corporate strategy, and the real estate investment trust (REIT) has one of the largest portfolios of Green Star-rated properties and green buildings in South Africa. The company considers green buildings as one of the most cost-effective solutions to climate change – one that provides significant environmental, economic and social benefits. Growthpoint maintains a focus on creating a positive work experience for each of its own employees, as well as driving sustainable impact for the communities in which it operates.

Aiming for carbon neutrality

Head of Sustainability for Growthpoint Properties Grahame Cruickshanks says, “Growthpoint has committed that all buildings within our direct control are targeted to operate at Net Zero carbon by 2030, and all buildings by 2050. Our target for Carbon Neutral 2050 includes a multipronged approach: to build, own and operate a portfolio of energy-efficient buildings across all sectors where we have assets (office, industrial and retail, plus our Healthcare and Student Accommodation funds); to optimise onsite renewable energy opportunities, primarily through rooftop solar installations; and to make use of wheeling agreements to access off-site renewable energy.

“144 Oxford represents points one and two, with the possibility of wheeling renewable energy to the building once viable within the City of Joburg.” Obtaining the initial design rating for 144 Oxford was step one of the journey to achieving a 5-Star Green Star Office As Built accreditation, which it did in June 2023.

trailblazing design

The 144 Oxford Street development was Growthpoint’s definitive response to an increased demand for premium office space in the sought-after suburb of Rosebank.

The architects, Paragon Group, crafted a dynamic, certainly dramatic building that not only secured rockstar presence on Oxford Street, but most importantly, through the entire design process, also placed sustainability alongside aesthetics to imagine a building for the future. Constructed as a joint venture by WBHO and Tiber, 144 Oxford is the Rosebank landmark in a landscape marked by innovative design and architectural daring.

The building’s premium office space consists of nine occupiable floors and six basement levels for parking. Set right in the heart of a richly treed Johannesburg neighbourhood – across the road from high-end retail centres, hotels and the Gautrain station – the building’s dramatic facade is not only visually arresting, but the extensive glazing also reflects the momentum and energy of the ever-changing sky and passing traffic on the west side of Oxford Street.

This building was the perfect choice for leading global mining company Anglo American’s head office, where location, integrated sustainability features and goals, and iconic architectural design spoke directly to the organisation’s corporate image.

Mike Woodruff, Director of Origin Project Management, says, “From the very start, it was clear Growthpoint Properties was committed to achieving an environmentally sustainable building. This was demonstrated during the design process where good, eco-friendly design was promoted, and innovative and technology-forward thinking was encouraged.

“All the ‘greening’ design elements were reviewed in terms of the capital costs as well as life-cycle cost benefits. Origin ensured the professional team conducted thorough analysis of the long-term economic advantages associated with these design aspects, including factors such as reduced energy consumption, lower maintenance costs and benefits to the building users. 144 Oxford was completed on time and within budget.”

A feat of engineering

For the architects, awareness that this structure would form the “entrance” to the Rosebank urban precinct, as well as be part of the residential suburbs, was key. Visually, it’s breathtaking: two massive, curved wings clad in glazing – the office towers – linked by a nine-storey atrium. In essence, the two elongated “winged” towers cantilever outwards towards Oxford Road, and are interlinked by a towering central atrium which, with no column support, spans over 24m. The atrium roof support structure spans the towers, with tension rods supporting the nine-storey hanging glass curtain wall and four hanging steel-framed meeting pods. It’s a masterful feat of engineering. Woodruff described the process: “The beam was brought to the site in two sections, assembled on the road, and then lifted into position with a 400-ton crane. This required a partial road closure and had to be undertaken over a weekend. The operation was completed without a hitch.”

Zutari (formerly Aurecon) was appointed as the mechanical engineer and the environmentally sustainable design (ESD) consultant on the project. The ESD team was led by Yovka Raytcheva-Schaap, who explained: “We worked very collaboratively with an engaged and invested client, architects, professional team and contractors to ensure that the clearly defined sustainability objectives aligned seamlessly with the proposed design of the building and the building services. The goal was to design a building for optimal energy, water and material use, but always with a focus on enhancement of the occupants’ health, well-being and productivity.”

Whether you’re an onlooker, occupant or a stakeholder, the bespoke facade of 144 Oxford takes centre stage, a perfect example of the comfortable handshake between design and sustainability features. The glazing of the building went way beyond its dramatic visual impact. The main facade consists of double-glazed unitised facades, the outermost one featuring an offset glazed skin. This high-performance glazing had to account for the cooling load. Uniquely for this project, the glazing was coated and baked with a variety of chemicals to reflect the heat, so natural light enters, but heat wavelengths reflect back out. In essence, the glazing allows ample light penetration without excess solar heat gain, and maximises the occupants’ access to natural daylight, views and connection to the outdoors.

Energy-efficient innovations

Recycling is always front of mind, and this facade was designed so as to allow for disassembly and potential reuse, to minimise the embodied carbon emissions. Likewise, by means of recycling and reuse, over 70% of the construction waste was diverted from the landfill. The reinforcing steel has a recycled content of more than 90%. And to address the responsible handling of operational waste, a dedicated space for storage of recyclable materials is provided in an easily accessible location for service providers’ trucks.

At 144 Oxford, extensive consideration was given to the most appropriate type of HVAC system for the building and its intended use. The system needed to provide maximum tenant flexibility, least onerous maintenance requirements, low noise levels, and high levels of individual control. The use of four 800kW CIAT chillers was the chosen methodology, a system with the flexibility to capitalise fully on the seasonal changes experienced in Johannesburg, so natural cooling of the building can occur. All air-handling units have full economy cycles. Ultimately, the provision of outdoor air at 144 Oxford has rates exceeding national buildings standards’ requirements. Furthermore, a chiller study was conducted with a present-day cost analysis over a 25-year lifecycle to determine the most efficient chiller combination, bearing in mind there was a phased approach to the building’s two towers at the time of the system selection. The final HVAC selection provided not only a highly energy-efficient system, but also a cost-efficient design satisfying to everybody, all the requirements, and the budget.

Innovation featured strongly throughout this project, one of which was a solution developed by Zutari to detect refrigerant leaks from the air-cooled chillers. The mechanism deploys weighing cells, which are connected to the building management system (BMS) to continuously monitor the weight of the chillers. In that way, it detects even a minor refrigerant leak, thereby limiting the environmental damage caused by refrigerants with global warming potential. All refrigerants and gaseous fire suppression systems have zero ozone depletion potential.

In addition to the municipal supply, electrical energy is provided by the extensive photovoltaic (PV) array on the roof, with an annual production capacity of 285 000kWh. An energy-efficient lighting system is installed throughout the building, and includes zoning and daylight harvesting sensors to ensure lights are switched off automatically in spaces when not needed.

Waterwise, inside and out

Reduction or reuse of potable water was a constant focus. The sustainable approach to water consumption included efficient low-flow rated sanitary fittings – toilets, taps and showers. The irrigation system employs drip irrigation, soil moisture sensors and an automatic controller to reduce potable water use. So, too, water from routine fire protection tests is captured, stored and recirculated so as to facilitate the reuse of potable water. A 200kL tank for rainwater harvesting provides an additional capacity for water security and use of non-potable water.

The wealth of landscaping – both hard and soft – played a significant role in the overall look and feel of the building’s exterior and interior, and importantly, connected people to their natural surrounds. For the landscapers, complementing and reflecting the lines, shapes and character of the building meshed with the creation of enticing outdoor spaces where occupants can rest, refresh and breathe.

The indigenous waterwise planting, an ability to tolerate highveld extremes, and calculated design to amplify the occupants’ experience, was the province of Karen Marais of landscape architects, The Ochre Office. This was no easy feat, particularly in challenging areas such as that between the building’s two glazed wings, where extreme changes of sunlight, heat, direct sun and shade were a constant. Equally challenging was the decision to plant over the basement slab above the six levels of parking, as well as the raising of landscaping material up to the podium slabs – from benches and pebbles to 600m3 of planting medium, 10 000 plants and 52 trees.

In pursuing the 5-Star Office As Built GBCSA accreditation, 144 Oxford’s proximity to the Gauteng train station, public transport and the retail sector is highly beneficial as it offers occupants various options for public transport and limits the use of private vehicles. For this, the project scored high in the Transport category.

Management and monitoring

Inclusion or installation of sustainability features is one thing, but ongoing effective management, monitoring and operation is crucial. Management was one of the highest scoring categories in 144 Oxford’s quest for the 5-Star Green Star Office As Built rating. It began with the comprehensive commissioning of building services facilitated by SEM Sustainability Engineers, an independent commissioning agent. The facilities manager was actively involved during the design phase to ensure that the operational intent of the sustainability initiatives was effectively implemented.

Growthpoint Properties will be taking its climate response to the next level by implementing a robust and viable carbon-neutral strategy. For Raytcheva-Schaap, “144 Oxford is the latest addition of a large office building to Growthpoint’s portfolio. The building is fully geared to support the company’s vision and that of Anglo American, the largest tenant in the building, for a more sustainable future and to contribute to achieving their carbon reduction targets.”