A GEM of SUSTAINABLE INNOVATION

Project nutshell

When Divercity Urban Property Group built The Emerald in 2020, sustainability was already top of mind. The apartment building in the trendy cultural district of Maboneng in Johannesburg is part of Jewel City, a housing district that comprises three developments: The Emerald, The Onyx and The Diamond. “On this site in particular – at the junction of Jewel City – we wanted a building that lowers running costs for residents, reduces grid and water demand, and sets a new benchmark that others can follow,” explains Tommie Richards, Development Manager of Divercity Urban Property Group.

For the developer, sustainability and affordability go hand in hand. Divercity has been recognised as an International Finance Corporation (IFC) Excellence in Design for Greater Efficiencies (EDGE) Champion, one of only a handful of African companies chosen by IFC to accelerate green building adoption. This has enabled Divercity to spearhead the sustainable and inclusive development of well-located and affordable housing in amenity-rich, mixed-use environments.

“Going green can be expensive if it’s an afterthought,” says EDGE consultant Yvonne Pelser of Inside Out Consulting. “For Divercity, sustainability isn’t just about certification – it’s about designing buildings that cut operational and utility costs for landlords and tenants alike.”

Knowing that Johannesburg has a dearth of rental housing at rates of under R8 000 per month, Divercity was determined to fill this gap with the Emerald. Certainly, the rental prices for the neat, attractive apartments speak volumes: the monthly rent charged ranges from R3 399 for bachelor flats to R5 199 for two-bedroom apartments. For Richards, this commitment to affordability dovetailed with the quest to achieve EDGE Advanced certification. “EDGE Advanced rating validates that sustainable housing can be delivered at scale in the heart of Joburg without pricing people out,” he says. “For us, it’s a proof-point: efficiency, resilience and good urbanism belong together.”

DESIGNING WITH SUSTAINABILITY IN MIND

Designing a resource-efficient, eight-storey building within such a tight envelope wasn’t without its challenges. However, Charldon Wilken, director of Fieldworks Design Group, says their vision was always clear. “Our design vision was to deliver a resilient, dignified and affordable housing development that could contribute to the vibrant urban community of Johannesburg’s inner city.”

In order to balance affordability with sustainability, he says the architectural team designed lean, but high performing spaces that maximised natural light, natural ventilation and interaction as far as possible. “Careful consideration with regard to product offerings in terms of mixed-use shops below, different unit sizes, configurations and layout required many design refinements before a final layout was achieved,” Wilken states.

“The building also underwent various facade iterations to ensure the creation of the building’s envelope contributed positively to the urban fabric.”

Richards concurs that the building design underwent many iterative adjustments before the final layout was approved. “The main challenge we experienced was aligning the design team, contractors and suppliers around performance from day one, plus careful commissioning and documentation for certification,” he says. “Lock performance targets into the brief,” Richards advises. “Model early and often, focus on high-impact measures and treat commissioning as a core project, not an afterthought.”

Despite the constraints of the building, Wilken says he’s proud of the landscaping. “Green features were designed with indigenous, drought-resistant planting that reduces water demand and supports local biodiversity,” he comments. “The indigenous street trees contribute to softening the facade, while a planted rooftop garden gives residents access to a green, restorative environment.”

ENERGY SAVINGS

The fact that The Emerald achieved EDGE Advanced certification is a rare feat, considering that the project had to achieve at least 40% energy savings compared to a local benchmark. In the end, the building achieved an impressive 69% savings in energy consumption.

“Energy savings consist of two components,” Pelser explains. “Firstly, the passive-design elements in the building contributed to the energy savings through a low window-to-wall ratio, the thermal properties of the external clay brick walls and roof insulation. Secondly, the operational energy was improved through an efficient heat-pump system, as well as centralised solar PV for electricity generation.”

Richards agrees that good design decisions can make a big difference in reducing a building’s energy consumption. “We started with passive performance – orientation, shading, and a tighter building envelope to reduce heat gain and loss,” he comments. “High-efficiency lighting with smart controls, energy-efficient lifts and pumps, and efficient hot-water systems do the heavy lifting operationally. On site renewables round it out, so residents can see and manage their consumption in real time.”

According to Wilken, early modelling helped the design team maximise water and energy savings upfront. “Natural light did pose a challenge with narrow and deep units,” he concedes. “However, the building layout was optimised and a test unit was constructed prior to full construction in order to review the unit’s performance and efficiency. Only once this test unit was refined and approved did the full construction programme commence.”

While solar-power generation was not included in the initial scope of the project, he says the roof structure was designed in such a way as to provide adequate support for future development, which has since come into operation as a result of the certification.

WATER SAVINGS

Similarly, the predicted water savings were considerable, at 32%. “Water savings were achieved through the retrofitting of water-efficient aerators for all taps and water-efficient regulators for all the showers,” says Pelser. “Existing toilets were single-flush and were retrofitted with a special flush valve to reduce the volume per flush.”

As Richards notes, the efficient hot-water systems also helped. “We designed to total cost of occupancy, not just upfront rent, as lower utility bills make monthly living costs more predictable,” he says. “Standardised modules, simplified details and competitive procurement helped us keep CaPex in check. We then prioritised these measures with the best payback for residents, especially those that reduce electricity and water bills from day one.”

This combination of environmental efficiency with everyday liveability is part of The Emerald’s appeal, Wilken maintains. “Fieldworks was committed to adhering to best practice standards, making sure that sustainable elements were enhancing daily life without restriction,” he asserts. “Plumbing tests were conducted throughout the build in order to ensure that there was a balance between efficiency and user experience of low-flow taps and showers, as well as dual-flush toilets.”

EMBODIED CARBON SAVINGS

Achieving EDGE Advanced certification requires a high level of technical efficiency. In terms of embodied carbon in materials, The Emerald achieved a 99% reduction. Pelser explains how this was achieved: “In EDGE, when a building is older than five years and the existing materials are reused, the project can claim for the reuse of materials.” Because The Emerald was an existing building completed in early 2020, all the project had to do to achieve EDGE certification was to undertake retrofits to improve the water savings and install solar PV. “The whole building structure qualified for the reuse of existing materials,” she says. “This relates to the slabs, external and internal walls, as well as the roof and windows.”

In order to reduce the embodied carbon of the entire build, the architectural team made sure they prioritised locally sourced materials. “Both the stock brick and facebrick were chosen because they were manufactured less than 50km away from the site, reducing transport cost and emissions,” states Wilken. “The simplicity of materials and construction methodology helped improve the buildability and reduction in material waste, further reducing the embodied carbon of the build.”

Material sizes, such as brick scale, were used from the start in order to determine the size of rooms, facades and heights. “This was very rewarding to integrate, as it not only provided interesting brick-facade details, but also contributed to a reduced wastage of material during construction,” Wilken says.

WHAT’S NEXT?

According to Pelser, there is momentum building in the local market to scale EDGE adoption both in the private and public housing sectors. “EDGE is becoming very popular in South Africa and beyond our border,” she comments. “It allows developers and landlords to differentiate their product in a competitive market. The current incentives from banks, offering green home loans and development loans, has helped to fast-track EDGE to become more mainstream than a few years ago.”

Looking ahead, Richards believes that they will apply the lessons learnt to future projects. “The Emerald sets our new baseline – every project aims for measurable efficiency with transparent operating costs,” he concludes. “We’re scaling resident education, expanding on-site renewables where feasible and deepening water resilience. The vision is simple: dignified, well-located housing that costs less to live in and strengthens the city, block by block.”