The Sisonke District Office in Ixopo, KwaZulu-Natal, is a flagship example of how green building design enhances environmental performance. Its green roof is more than just insulation – it is a living, growing ecosystem that keeps on growing. 

The offices consist of two single-storey buildings, namely the office block with a conjoined maintenance block and a separate garage block. 

When built, the Sisonke District Office for the Department of Public Works in KwaZulu-Natal received a prestigious five-star Office Design rating and the highest quality Green Star SA Accreditation award from the Green Building Council of South Africa (GBCSA). 

Cost saving 

Section detail of the build-up of the green roof.

To reduce energy consumption, the offices are naturally ventilated and 85% of the interior spaces are daylit from natural light. Motion sensors automatically switch the lights off when no one is in the spaces. 

The heavy nature of the floors, walls and ceiling slab provides thermal mass, which acts as a heating mechanism in the winter. Water is heated by a heat pump and circulated through the walls. The thermal mass of the building is able to store the heat, so the heat pump can use off-peak electricity to reduce costs. 

Another important consideration was local sourcing of the building materials, where the face bricks used in the construction were sourced within 100km from the site. 

Roof garden insulation 

The office block has an extensive roof garden that is home to nearly 100 indigenous plant species, which optimises the insulation properties of the building. This plays a vital role in regulating the building’s temperature and enhancing its environmental performance.  

Acting as living insulation once the plants were established, the roof requires no irrigation and minimal maintenance. 

The extensive roof garden is home to nearly 100 endemic plant species.

Low-tech systems, high-impact performance 

The Sisonke green roof showcases passive design and energy efficiency principles, demonstrating how low-tech natural systems can elevate the building performance. The main principles include: 

• Evaporative cooling: Moisture in the roof soil from the summer rains cools the surface through evaporation, helping to lower indoor temperatures during the summer, without increasing the humidity.  
• Insulation: Primarily effective in the winter, the green roof and masonry wall reduce heat loss, helping to maintain warmth indoors during the colder months. 
• Thermal mass: The concrete structure and masonry walls stabilise internal temperatures by absorbing and gradually releasing heat, keeping the indoor climate steady.  
• Passive solar gains: The building’s north orientation, paired with carefully designed shading depths, maximises sunlight in the winter while controlling direct solar exposure in the summer.  

These strategies offer a practical, affordable solution that requires minimal maintenance over the long term and deliver energy efficiency and comfort without high operating costs. 

This pragmatic approach, grounded in simplicity and durability, makes it an accessible model for other public buildings aiming for low-cost, high-impact environmental design.  

Project details 

Architect: Steve Kinsler Architect. 

Client: KwaZulu-Natal Department of Public Works. 

Location: Ixopo, KwaZulu-Natal. 

PJC services: SDM, PLED, WMS, MES. 

Photos: Architect, Steve Kinsler. 

Environmental design concept: PJC & Partners. 

Full thanks and acknowledgement go to www.pjc.co.za for the information in this article. For more information, visit https://eastcoastarchitects.weebly.com/.