Construction World December 2023

BUILDING CONTRACTORS

AfriSam Innovation Award for Sustainable Construction

EASTGATE SUSTAINABILITY PROJECT I n a three-pronged project to improve the sustainability, efficiency and resilience of Liberty Two Degrees’ Eastgate Shopping Centre in Bedfordview, Johannesburg,

roof also means that heavy equipment cannot be used to carry machinery or materials to the working areas. The project is all about sustainability – from energy generation and water conservation to making the best use of available energy and taking significant load off municipal supply which is already under stress. The extended solar generation facility will add 5,74 MW of solar power to the centre’s renewable capacity, reducing the carbon footprint and taking a welcome load off the national grid. The rainwater harvesting system demonstrates the commitment to water conservation by making optimal use of scarce water resources. It provides another constructive example of how the private sector can support society’s call for responsible water stewardship, and will undoubtedly be followed by other shopping centres. The upgrade of the HVAC system is an advance in both energy and water efficiency. Using energy efficient technology, it will optimise power draw and its closed water loop means that water is no longer lost to evaporation. The solar domes are designed to match the existing solar structures from Phase 1 of Eastgate Shopping Centre’s evolution to renewable energy. In this design, PV panels are fitted closely to create a high and sealed roof effect. This will function to protect shoppers and their parked vehicles from sun and rain, while still allowing sufficient cooling air movement under the dome. The CAD design of the complex steel framework to support the panels was important in meeting the project’s tight timelines. It was designed well in advance and premanufactured to allow easy assembly without on-site cutting and welding. The visual impact of the HVAC building on the roof will also be enhanced by a perimeter louvre structure that is designed to hide the equipment from the view of shoppers. 

Concor was engaged to execute three different construction elements. These are the extension of the solar energy generation plant, the installation of rainwater harvesting, storage and treatment facilities and the upgrade of the heating, cooling and ventilation (HVAC) system. Underpinning each of these fast track sub-projects is the demanding condition that trading activities at this busy shopping centre must be allowed to safely continue undisrupted. At a technical level, there are myriad challenges which the Concor team is successfully overcoming through careful planning, efficient execution and skilled workmanship. Solar Energy Generation Plant: The solar energy system – the second phase which augments an existing installation – covers 30 000 square metres of the roof top parking area. It comprises concrete stub columns supporting a steel framework of girders and trusses, on which photovoltaic (PV) panels are mounted. Rainwater Harvesting, Storage and Treatment Facilities: The rainwater harvesting facilities comprise two large water tanks which will store water from the roof top run off and groundwater under the centre, as well as pipework and a water treatment system. HVAC: The HVAC upgrade involves the installation of heavy chiller units above an existing building on the centre’s roof top – requiring extensive demolition and strengthening work to bear the added load. In executing this project, Concor has adopted various construction innovations to address the technical complexity of working on a shopping centre roof parking level with low load bearing capacity, and conducting work safely and efficiently within a live environment where tenants and shoppers continue trading. Aligning with existing columns For the solar energy generation facility, the weight of the steelwork domes and PV panels could not be supported by the roof slab itself, so the layout of the supporting stub columns (as would have been usual with ground-based solar farms) is not uniform. Protecting post-tensioned cables An added challenge of this endeavour is to accurately locate the existing column heads below the roof top parking’s tarmac, and open them up without damaging the post-tensioned cabling in the slabs. No heavy equipment The limited load bearing capability of the shopping centre

PROJECT INFORMATION

• Company entering: Concor Construction • Client: Liberty Two Degrees • Main Contractor: Concor Construction

• Architect: Batley Partners • Principal Agent: Origin PM • Project Manager: Origin PM • Quantity Surveyor: Acost • Consulting Engineer: Zutari

38 22 nd Best Projects Awards 2023