Geared for a green future

by Ofentse Sefolo
Geared for a green future

Not only is Mutualpark, Old Mutual’s offices in Pinelands, Cape Town, the largest office building in South Africa to achieve five-star Green Star certification from the Green Building Council of South Africa (GBCSA), it also has the largest corporate carport solar installation.Solar carports
Home to more than 7 000 employees, Mutualpark is one of the largest consumers of electricity in the Western Cape, but with an output of just over 1MWp, the solar system will produce enough electricity to reduce the offices’ consumption with up to 8% and free up a significant amount of electricity on the City of Cape Town grid. This equates to one free month of Mutualpark’s electricity per year, or about R4,5 million per year in optimal conditions.

Switched on in December last year, the solar installation consists of 3 600 photovoltaic panels over an area of about 14 500 m², covering 565 carports.

Greening an existing building
In October, even before the solar factor came into play, Mutualpark also achieved a five-star Existing Building Performance rating. Seeing that some of the buildings date back to 1954, this remarkable achievement debunks the myth that green building performance is only possible in new buildings.

According to Green Star SA accredited professional, Khiyam Fredericks, a number of technologies were implemented over a period of seven years to reduce the building’s carbon footprint.

“The major challenge and biggest effort was to create proper policies for several of these managed areas, as well as sustainable baseline measurements that we could record performance against, and then constantly work on improvements to ensure we meet sustainable targets,” he notes.

Indoor environmental quality (IEQ)
As a person’s experience of a building is greatly influenced by its IEQ, this was an important consideration. Fresh air in the building far exceeds the rate of 15l/s/p, and there are no smoking areas within the building or at entrances. Formaldehydes and volatile organic compounds (VOCs) are also minimised.

High frequency ballasts and T5 lamps reduce the flickering of florescent light fittings, while the average maintained illuminance level is automatically controlled by light sensors that react to the presence of natural light, of which there are plenty, or turned off completely if the space is vacant.

All windows have been treated to reduce heat penetration and block-out mechanisms were fitted to the northern facade. Areas with similar heating and cooling demand were grouped together and low pressure variable air volume (VAV) systems were implemented to reduce the amount of air supplied under part-load conditions. Efficient LED lighting and occupancy sensors have also been installed.

During the first phase of the centralisation of all chillers into one cooling plant,  11 chillers were replaced by just 3 more efficient ones. Phase 2 is currently underway, and will see the replacement of a further 12 chillers with 2 bigger, more efficient ones. Variable speed drives now also allow for greater control of fans and pumps.

The lifts are upgraded with energy-efficient motors and control systems when it reaches end of life, while the escalators have sensors to reduce the speed and energy consumption when no one is using the system.

All transformers are sub-metered and energy meters were installed to monitor energy consumption through a web portal on a monthly basis.

Through the use of efficient water fittings and flow restrictors, using bleed off water from the HVAC system to flush toilets and watering sports fields with recycled sewerage water, the potable water consumption has been reduced by 12,5% when compared with the previous year and the load on the municipality’s potable water grid has been reduced.

“Although managing a building is a physical thing, having a building rated and managed as a green building is predominantly about people and behaviour change,” Fredericks adds. As part of the strategy, for example, building occupants are encouraged to use water and electricity sparingly and report any leaks to a helpdesk.

Looking forward
In Johannesburg, construction is on track to complete Old Mutual’s new 12-storey, 30 000m² head office in Sandton by the end of 2017. The new building will also target a five-star Green Star SA rating for New Buildings and office design.

Full thanks and acknowledgement are given to Old Mutual for the information given to write this article.

Caption: The solar installation at Mutualpark consists of 3 600 photovoltaic panels over an area of about 14 500², covering 565 carports.

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