The design and implementation approach was to promote the benefits to this 4 Star structure, which include reduced carbon footprint, lower energy costs, reduced water costs, increased productivity and market leadership in sustainable buildings.
The sustainability team is currently compiling As Built documentation for submission to the Green Building Council of South Africa for the pursuit of a 4 Star Green Star As-Built rating.
For this project, WSP formed part of a design team, Akani Consortium, inclusive of a project manager, quantity surveyor and architect – with multi-disciplinary technical skills and services provided by WSP, including full scope of engineering (across structural, civil, electrical, mechanical, lifts, fire, electronic, wet services etc.) and sustainability consulting.
Roxanne Dovey, WSP Sustainability Consultant, says: “The Agrivaal building and site was already owned by DPW and, from the client’s point of view, there was never any doubt on the desire to have a sustainable building. Green or sustainable building considerations were included in the early design concepts for the building. This works very well, as the earlier sustainability is given consideration on a project, greater positive impacts and results for an efficient building can be achieved.”
Some of the heritage-sensitive and environmentally innovative features of this project include:
- The indoor environment quality is characterised by vast amounts of day light, access to external views and low volatile organic compound finishes. Daylight glare is reduced by internal manual blinds and external shading.
- The building opted to make use of efficient lights for 100% of the office usable area, which resulted in an achieved average lighting power density of 1.78W/m² per 100 Lux.
- The building has an extensive metering and monitoring system, as well as an energy-efficient DALI lighting system.
- Energy modelling demonstrates that the building has the potential to perform 40% more efficiently than a SANS minimum regulation building.
- The hydraulic system exceeds the most water efficient GBCSA benchmark through low-flow fittings, rain-water harvesting and grey water filtration for reuse in the building.
- The building’s central hot water system is supplied from solar water heating and therefore has very little electrical resistance.
- Portland cement has been replaced by 40% for all concrete on the project, and at least 90% of all construction steel is recycled.
- Bicycle spaces and facilities have been provided for building occupants and visitors to encourage users to assist in reducing road congestion and levels of potential pollutants from other means of transport while providing the building users the opportunity to reap substantial personal health and economic benefits.
- Roof-top gardens have been planted and the building is reaping the benefits. The ecological value of the site was enhanced by introducing more soft landscaping, which includes indigenous plants, and the irrigation comes from the water reuse systems. The roof-top gardens also act as a natural insulation barrier for the building below, which reduces the cooling load on the mechanical system. They also limit the storm water run-off, reducing the peak storm water impact on infrastructure.
- A generator with a motor that is EPA Tier II compliant and at max standby power operates at 560kW has been installed to further reduce potential nitrogen oxides (NOx) emitted into the atmosphere from burning fossil fuels during times of power outages.
“This was a challenging project, especially given the time frame, from commencement to construction and then occupation – which was longer than usual with commercial building projects. Over this time, the design team needed to closely monitor the sustainability aspects through changes in both the designs and people involved in the project to ensure consistency was maintained and that we achieved compliance and met the criteria for the 4 Star Green Star rating,” explains Dovey.
The project has set a benchmark for public sector buildings in South Africa. And, in time, the investment by DPW into the CBD will not only have positive social and economic sustainability spin offs, but will rejuvenate an important business node as part of the long-term strategy to revitalise Tshwane.