News

2 November 2011

MURRAY AND ROBERTS WESTERN CAPE MEETS CHALLENGE OF CONSTRUCTING SOUTH AFRICA'S FIRST FIVE STAR GREEN BUILDING

The construction of South Africa's first five star rated green building was a challenge accepted by Murray & Roberts Western Cape as a maiden green project that would showcase the company's ability to meet the exacting demands required by the Green Building Council of South Africa (GBCSA).

The view of the new Aurecon office building as seen by passersby at Century City in Cape Town. The building is at the corner of Century Boulevard and Canal Walk Road.

"Bidding for the appointment as the main contractor on Aurecon's new office building in Century City required careful scrutiny of the contractual requirements on the basis that we have had limited exposure to undertaking projects which have high-end green star accreditation as a priority objective," Chris Prodehl, senior contracts manager of Murray & Roberts Western Cape, says.

"Our risk analysis indicated that our existing skills and expertise were of a standard that allowed us to submit a tender that was the lowest of the six received." Prodehl indicates that the initial objective of achieving a four star rating was surpassed and the building received the CBCSA's 5 Star Green Star SA – Office Design v1.

"Our strategy was to ensure that every member of our project team understood the green requirements of the project. We submitted an environmental management plan to the client that included a method statement for each activity. Thereafter, members of the construction team attended a green star related course conducted by Enviroserve where personnel were trained on the use of two spill kits provided by Enviroserve for use on the project site."

The building comprises semi-basement level parking, ground floor with an external parking deck, three levels of office space and a roof with garden and entertainment level. There is 7 402 m² of commercial office space and 6 138 m² of parking.

The HVAC air handling units and plant with the cooling tower situated on the roof behind the slatted screen.

The Murray & Roberts Western Cape project team as well as all sub contractors were tasked with adhering to the extensive list of requirements so as to gain the points necessary to achieve the required rating.

"We implemented the green approach from the first day on the project site in August 2010, starting with the structural work," Prodehlsays. "Silt sumps were constructed for the cleaning of concrete plant and equipment and water was tested for compliance prior to being pumped out to municipal sewers during the construction period."

In the event of any spillage of hazardous materials on site, a spill kit was available for the cleaning up of such material, which was then placed in the hazardous material store awaiting removal by Enviroserve.

Regarding management of waste, an estimated 90% of waste such as steel and rubble was recycled and quarterly waste reports were maintained to track performance.

Extensive use was made of recycled materials. An estimated 90% of steel reinforcing comprised recycled product and all timber used in the project was certified to have been harvested from sustainable forests.

The use of products such as paints, glues and carpets was limited to those which had a less than an allowable volatile organic compound (VOC) content while HDPE products were specified and installed for all drainage and other plumbing applications.

Environmental requirements extended to the transportation of building materials to site. Points were awarded for sourcing materials as close as possible to the site.

A tight deadline of 12 months was set for the project hand-over successfully undertaken on 19 July this year (2011). A monthly monitoring of building performance and a full re-commissioning 12 months after practical completion are required in terms of the contractor.

Project architect Johan Sadie of Maas and Coetzee Architects in Cape Town says the Aurecon building was positioned to reduce the effects of the south easterly wind and to provide more exposure to the northwest for a view of a bird sanctuary. The site was also chosen because of its proximity to residential, retail, commercial and recreational facilities.

"The interlinked issues of heating, cooling, natural light and their impact on environmental savings, operating costs and staff morale were addressed.

"The depth of office space was limited to 8 metres from the outside windows to the glass wall facing inwards onto a central atrium. Tinted, high impact glass with low E capabilities was used for windows on outside walls to reduce external noise levels and to cut the influx of heat and damaging rays," Sadie remarks.

"A high volume atrium in the centre of the building provides natural light to the core of the structure. External sun screens also assist with the control of light and heat into the building. The north facing recreation area on the roof top provides staff with a relaxation zone amid substantial plantings.

" The consumption of electrical power is controlled and monitored by an intelligent building management system (BMS). High volumes of fresh air are pumped through the system to flush out stale air. Carbon dioxide sensors monitor fresh air adjustment. All refrigerants in the building are ozone-friendly with a rating of zero. Overall, the systems employed in the building reduce greenhouse gas emissions by an estimated 50%. Low voltage lights with high frequency ballasts and fitted with motion sensors were used in the offices and in the parking garage.

The entry of light to the core of the building has been promoted by large expanses of glass at rooftop level. The entertainment area and rooftop plantings provide an excellent relaxation facility for Aurecon employees and guests.

Water usage has been reduced by fitting low volume plumbing fittings, including sensor taps and urinals and one-flush toilets. The installation of efficient fixtures has resulted in a 50% reduction in sewerage from the building.

Rainwater is harvested and used for toilet flushing while grey water recycled by Century City is used to irrigate indigenous, water wise plantings on the inside and outside of the building, including the high volume atrium. The harvesting of rainwater minimises the flow of storm water from the site. All water consumption is monitored and managed by the BMS.

Murray & Roberts Western Cape achieved excellent safety levels through the introduction of a performance-based safety system. A total of 507 384 lost time injury free (LTIF) hours was logged on the project.

Although initially aiming for a four star green rating, the attention paid to the requirements by the main contractor, sub contractors and all professional staff working on the project resulted in the building becoming the first in South Africa to achieve a five star green rating.

A total of 5 500m³ of concrete, including vertical and horizontal formwork, as well as 560 tons of steel reinforcing, was used in the construction of the building. The total construction cost of the R130m building amounted to R92m.