11 September 2014 - The Green Building Council SA (GBCSA) has certified more than 60 buildings with Green Star ratings since its inception in 2008. Each Green Star submission requires meticulous preparation of design documentation to be submitted to the Green Building Council and external assessors for evaluation. Aurecon recently won the award for ‘Best Quality Submission’, announced at the 7th annual Green Building Convention, which took place on 10 – 12 September 2014 at the Cape Town International Convention Centre.
The winning submission was for the Atrium on 5th building situated in the CBD of Sandton. The project was commissioned by the owners Liberty Properties and Pareto Limited, and involved a complex refurbishment of the existing Twin Towers offices located directly above the Sandton City shopping mall.
Jeanne Butler, Aurecon’s Environmentally Sustainable Design project leader for the Atrium on 5th redevelopment, says this award is a reflection of the team’s ability to deliver high quality projects that meet and exceed the stringent GBCSA requirements.
Aurecon provides the full gamut of ESD and engineering services and has worked on iconic green projects throughout South Africa, Africa and the rest of the world. In South Africa, Aurecon consults on and provides expert engineering services to maximise building performance and to enable clients to obtain coveted Green Star certifications.
“This Green Star SA Leadership Award demonstrates what can be achieved when clients partner with ESD and engineering consultants who have in-depth industry knowledge as well as a solid understanding of what it takes to design a green building and to achieve certification” comments Butler.
Previously known as the Sandton Twin Towers, this iconic 32 year old building in the heart of the Sandton CBD has undergone a major refurbishment, with sustainability being a high priority for the development. With a total rentable floor area of 24 713m2 spread over 11 floors, the large majority of the original structure has been reused. The outdated exterior of the building was transformed by the addition of a new façade and glass atrium linking the two towers across all floors.
“The reuse of the existing structure reduced the environmental impact of the project. However, it also presented a number of significant challenges to the project team in order to achieve a high performance and workable solution,” says Martin Smith, Aurecon’s National Green Building Expert.
In a bold design move by the architects, the building’s overhanging beams with recess windows were transformed by cloaking the building in a high performance double glazed unitised façade to lend the building a modern, sophisticated feel. This allowed an increase of the floor area by approximately 334m² per floor.
Because the new reclaimed recess area is close to the façade, the project team needed to ensure that building occupants wouldn’t be affected by increased radiant heat from the now full height glass façade. Installing conventional cooling systems below the perimeter beams proved problematic.
“Aurecon’s advanced building sciences specialists used Computational Fluid Dynamics modelling to assess thermal comfort in the areas closest to the façade. This saw us analyse several cooling systems before finally settling on a combination of an advanced skin system and active chilled beams around the building’s perimeter,” says Smith.
Advanced CFD (Computational Fluid Dynamics) modelling was done on the design to assess the thermal comfort in the perimeter zone against the façade.
A number of other sustainable and energy efficient initiatives were also included on the project:
- A new VAV air conditioning system with economy cycle.
- Efficient air cooled chiller plant including a high performance ammonia chiller with zero Global Warming Potential
- Energy efficient T5 and LED light fittings with occupancy sensors throughout office areas
- Heat pumps used for water heating
- Water saving fittings and a fire water system that recirculates test water
- More than 70% of timber specified is Forestry Stewardship Council certified
- More than 60% of the office areas has a view to the outdoors or into the atrium
- A green wall in the atrium housed in a unique crate system made from recycled material
In conventional development projects, the overall vision for the project is created and then handed to the design team and contractors who then take care of everything from cost evaluation to design refinements. With green development projects, however, all the sustainability factors need to be planned and designed from the initiation phase. In order to achieve optimised project outcomes, collaboration across the entire project team is required.
“Aurecon prides itself on working collaboratively with clients to achieve high-performance buildings that meet tight time and budget constraints. Atrium on 5th is an exceptional example of working with a visionary client toward this aim.”