In Parktown West, Johannesburg, a contemporary alteration and addition to a heritage Cape Dutch house exceeded the goal of a net-zero waste project and achieved a net-positive waste rating. 

The original house, which was built in 1915, is well over a hundred years old. It was not in a liveable condition and so the brief was a major renovation of the entire home and outbuilding, including increasing its footprint slightly. 

This project’s net positive rating was a first in South Africa. In the light of the growing interest in net-zero waste, this article explores the interventions employed on site. 

Embracing zero waste  

Led by the architects, Marc Sherratt Sustainable Architects (MSSA), the attitude of the professional team and contractor was one of reuse and recycle. Strict heritage sensitivity and a tight budget helped the team to creativity reuse items that would ordinarily have gone to landfill. 

Net-positive defined 

Strict heritage sensitivity and a tight budget helped the team to creativity reuse items that would ordinarily have gone to landfill.

This project generated just under 90 tons of construction waste. The Green Building Council of South Africa’s (GBCSA’s) definition for a net-positive waste building is that 5% above the total mass of construction waste produced, must be waste from other sites that is reused on a project. 

The Parktown Heritage Project was able to achieve 104% above the total mass of construction waste generated. What this means practically, is not only did no construction waste go to landfill, but the entire construction waste of a project of similar size was diverted from landfill and used as a resource on this project. 

Setting the standard for construction waste recycling, this tremendous achievement showcases that Johannesburg has great potential in becoming a leader in building contemporary architecture using what is termed as “waste”. 

Sustainability initiatives 

Natural gas is used for water heating and cooking, and rainwater harvesting for irrigation. The landscaping is mostly of indigenous plants from the area’s historic Highveld biome. 

Although small, this project showed that even residential renovations have an important role to play in the green building movement. 

The project uses natural gas for water heating and cooking, as well as rainwater harvesting for irrigation.

Project obstacles 

Effective monitoring 

The South African construction industry in general is extremely wasteful. The greatest obstacle on this project was setting up an effective monitoring system that the contractor could use to document all waste types to achieve net zero. 

A tight budget and very strict heritage requirements on the project meant the contractor had to be extremely delicate in the way he built. This helped the project see opportunities to reuse and recycle aspects that would normally have been replaced by new or sent to landfill. 

Central to making sure no waste “fell through the cracks” was how the site operated. 

Managing waste 

Large waste types such as timber, sheet and rubble were carefully managed in designated areas. Smaller waste types such as packaging were under the responsibility of sub-contractors themselves. 

This shared responsibility between contractors, professionals and the client meant a project where all gave input on possibilities for innovation regarding waste. 

Cost management 

Another obstacle was the additional cost associated with the administration around a rating of this nature on such a small project. 

However, true to the ethics of the team, the submission costs to the GBCSA were shared equally by the client, the architect and the contractor. 

A project that proved that even small projects can make a big impact, exceeding net-zero goals to achieve a net-positive waste rating. 

Full thanks and acknowledgement go to MSSA for the information in this article.