The Rewardsco Block B building in Umhlanga was yet another building in its A-grade commercial precinct to achieve a 5-Star Green Star certification late in 2021.

Words WORDS Kim Maxwell IMAGES Karl Beath Photography

Project nutshell

Project floor area: 4 973m²
Carpark area: 4 937m²
Project certification date: November 2021
Green Star rating: 5-Star Green Star Office Design v1.1
Location: Ridgeside Drive, Umhlanga Ridge
Type of building: High-performance office block

Makhosazana Mthethwa has been an architect and sustainable design consultant at Solid Green Consulting in Johannesburg sinceUnder her guidance and expertise, the company’s sustainable building design input in the Rewardsco Block B office building in Umhlanga Ridge, eThekwini, helped achieve the precinct’s five-star Green Star Office Design v1.1 certification, in November 2021. Block B is the Umhlanga commercial precinct’s second Rewardsco building with a Green Star Office Design certification from the Green Building Council South Africa (GBCSA). The first Rewardsco office, Block C, was completed in 2014.

The precinct has five office buildings and a hotel. The newest Rewardsco Block B has four levels of office space and three parking levels. Rewardsco is a leading provider of outsourced sales services, with its consultants working on behalf of blue-chip clients. The site is within walking distance of Umhlanga Arch and numerous amenities.

Mthethwa is in her thirties and has straddled a career that has morphed between pure architecture and sustainable design practices. “This means I help develop solutions to reduce the development’s environmental impact and carbon footprint. In that way, I guide the project design team to create comfortable, healthy buildings that are highly efficient in their energy, water and resource usage. Whatever the project requires, we work towards that,” she says. “I also coordinate the green design certifications for these buildings.

Rewardsco B Building in Umhlanga Ridge has a 5-Star Green Star certification.


“Sustainable design is impacted by every discipline – whether it’s architecture, mechanical or electrical engineering – we coordinate those designs and provide supporting green technical advice so we can achieve the project’s overall sustainability goals.” How might this be implemented? “With the architecture side, we look at how to help the project architect to optimise the building’s form, making sure that designs are well orientated. Or if there is a lot of glass, we’ll advise on climate-appropriate glazing selections, particularly for buildings with higher glazing ratios that would require high performance glass and perhaps shading solutions.”

Mthethwa says to predict a building’s performance, they carry out iterative computer base-model simulations for solar control, daylight availability, thermal comfort and energy analysis. “Using this simulated modelling allows us to give the design team an idea of the impact of different design variations – for instance, the impact of solar control on daylight availability and thermal comfort.” Where required, they also assist with post-occupancy surveys that offer user feedback on how occupants experience the buildings once completed.

“It’s important for sustainable developments to have all members of the design team collaborating quite early in the design process, starting from concept to close-out, and even through to operations. In the sustainable design world, we call it the integrated design process,” she says. This results in balanced designs and reduced resource waste.

Makhosazana Mthethwa

Makhosazana Mthethwa has been a green building consultant at Solid Green since 2018. Her role is to facilitate green building design certifications as well as technically assist project teams to deliver sustainable buildings. Mthethwa is also an assistant lecturer at UCT for the Simulated Office School of Architecture, Planning and Geomatics faculty. Before joining Solid Green, she was a design architect at dhk where she used her experience to incorporate sustainability initiatives into the architectural designs from concept level. From 2009 to 2015, Mthethwa worked at PJCarew Consulting. She joined as an academic intern and a year later began working as a green building design consultant. Thereafter she moved to part-time work to pursue a master’s degree from 2012.


Green certification for Rewardsco Block B was based on improving the facility’s energy performance, water savings and waste management. Mthethwa’s team focused on the following aspects:

The building has a modelled energy consumption of only 168kWh per square metre for each year, far lower than industry requirements. Sub-meters and an automated monitoring mechanism manage energy consumption. Carbon emissions were also reduced to much lower than a building constructed to South African national standards. This reduction in energy consumption and greenhouse gas emissions is due to:
– An optimised building façade, including highperformance glazing where required.
– Energy-efficient LED light fixtures.
– Occupancy sensors for all enclosed spaces, and open-plan office areas no bigger than 100m² (so lights burn only when needed).
– Energy-efficient HVAC system equipment.
– An efficient heat pump for hot water production.
– Office harvesting of natural daylight to offset electrical lighting.

The building uses non-potable rainwater – collected through the site’s stormwater attenuation and retention ponds – and is pumped to several of Block B’s water storage tanks. That means only non-potable water is used for landscaping, toilet/urinal flushing and heat rejection. Water-efficient sanitary fittings were also installed. The building’s sewerage outflow from occupant usage was reduced by 50% compared to the average practice benchmark.

To reduce operational waste, recycling waste sorting bins are provided in the basement waste area. This allows for the collection and eventual recycling of cardboard, paper, glass, plastics and metals.

Building occupants benefit from ample quality fresh air. The fresh air system improves on industry rates per person requirements by 66% with 12.5 litres per second per person. This impacts occupants’ abilities to keep alert, minimises building of indoor pollutants and mitigates sick building syndrome. Low-level VOC adhesives, sealants and carpets are installed in at least 95% of the fit-out. The building offers access to good levels of daylight and external views, to mitigate eye strain and provide general stress relief. More than 80% of ground floor and office floor plates have direct access to external views. Recreational and restorative spaces such as pause areas, prayer rooms, outdoor seating and break places also contribute to building occupant wellbeing.

Building occupants benefit from ample quality fresh air.
The Rewardsco buildings are all connected by bridges.

With Block B, one of its most special features is the water system linked to the attenuation and retention ponds.
Restorative spaces such as pause areas, outdoor seating and break places contribute to building occupant wellbeing.

Aside from design input in Rewardsco Block B last year, Mthethwa is currently involved in the Rewardsco Block A building too (the latter still under construction). “The buildings are all connected by bridges, as they have the same main tenant Rewardsco, so A and B are quite similar,” she says. “We are targeting a Green Star Office Design v1.1 rating for Rewardsco Block A too.”


What did she find memorable about working on the completed Rewardsco Block B? Mthethwa’s focus was on the building’s sustainability elements. “Sometimes with large developments, what looks like a water feature is used as a water retention pond to hold storm water,” she explains.

“With Block B, one of its most special features is the water system linked to the attenuation and retention ponds. As part of the Umhlanga Ridge precinct design, the ponds have additional capacity to store water. They are used for toilet and urinal flushing, as well as landscape irrigation and heat rejection.” All five office buildings draw from the ponds, thanks to some early design decisions.

This project is a perfect example of how all members of the design team have collaborated from concept to closeout.
Rewardsco is proof that an integrated design process results in balanced designs and reduced resource waste. Thinking smart for a sustainable building future.

The building offers access to good levels of daylight and external views, to mitigate eye strain and provide general stress relief


Main contractor: Trencon
Client: Zenprop Properties
Value: R92-million
Project: Construction of an 8 000m2 new office block including a podium, an external link bridge connecting an existing office (Block C) to the new office (Block B), and three basements of 6 000m2.

Yavani Singh-Ninan (left) and Aradhna Singh-Sewdial (right).

A five-star Green Star Office Design v1.1 rating was achieved for Rewardsco Block B. A four-star Green Star As-Built submission on this project is being reviewed by GBCSA currently.

“Trencon prides itself on its ability to deliver projects of high complexity on time and within budget, while contributing to the social environment that it operates in,” says CEO Yavani Singh-Ninan. The company has been involved in numerous projects that have achieved four- and five-star Green Star ratings. Trencon was the main contractor on Rewardsco Block B, and is also involved on Rewardsco Block A, under construction.

When founding member Dino Singh passed away in 2021, his daughters joined the management team, with Yavani Singh-Ninan as CEO and Aradhna Singh- Sewdial as human capital and transformation director.

“Our passion for women empowerment brings new energy and vision to a traditionally male-dominated environment,” says Singh-Sewdial. The sisters hope to build on their father’s legacy with “innovative and environmentally sustainable solutions”.

Accredited professionals on the Trencon team include their Green Star and environmental coordinators, Thembo Miya and Hendi Janse van Rensburg. Construction team members also attend an online Green Star course conducted by GBCSA. The project team is involved from the start until certification is achieved, ensuring compliance to targeted points.

All Green Star requirements are issued to Trencon’s sub-contractors and monitored, then distributed to buying teams to ensure compliance of materials. For instance, locally sourced, low-embodied energy materials used for building construction includes steel sourced from suppliers who have a high percentage of postconsumer recycled content, reducing resource depletion.