NERSA’s existing building achieves 4 Green Stars

NERSA’s existing building achieves 4 Green Stars

The National Energy Regulator of South Africa (NERSA) recently undertook a major refurbishment on an existing building located on Madiba Street, Arcadia, in the Pretoria City Centre. This included targeting a 4-Star Green Star SA Office v1.1 As-built certification, which was awarded in March this year.

Built in 1982, the NERSA building is now almost 40 years old. Accordingly, the aim of the refurbishment was to bring the building interior and services up to date to comply with the latest technology, standards, regulations and codes, while at the same time addressing the building’s current requirements and predicted future criteria.

Due to its location in the CBD, the building – which has eight floors and a GFA of 8720sqm – is well connected to local amenities and existing public transport infrastructure, and offers proximity to accommodation for staff or visitors. This enabled the project to achieve a high score under the Green Star Transport credits.

Zendré Compion, Senior Sustainable Building Consultant at Solid Green, explains that organisations should consider sustainability at the earliest stages of a new office project. “Choosing an existing building over a new building has major implications,” she says.

The impact of new construction, with the associated waste and urban sprawl, is significant. Green Star therefore rewards refurbishment projects for reusing as much of the existing building as possible, in this case the whole structure and façade; as well as for ‘Reuse of land’ under Land Use and Ecology, and for not impacting topsoil. In this instance, the building’s contribution to revitalising the city centre was also considered.

Compion adds that refurbishment projects are also rewarded for reduced environmental impact through a slightly simplified set of criteria because the material value comprises less than 1% of the contract value, so a number of the Green Star material credits fall away such as timber, concrete and steel.

While older buildings may be a challenge on some fronts, a potential benefit to refurbishment is that many of them were designed with good passive design principles – a practice that was slowly eroded as building thermal comfort became increasingly easy to manage with automated systems. In this case, the NERSA building has smaller glazed elements, large overhangs, external vertical blinds where the afternoon summer sun hits the building, and narrow floor plates.

A key focus for the refurbishment was the upgrading of the building’s major mechanical and water systems – which made it possible to target Indoor Environmental Quality (IEQ), Energy (ENE) and Water points. Energy modelling of the refurbished building design was carried out and the results indicated an improvement of 42% in Greenhouse Gas Emissions associated with operational energy consumption compared to a notional building model.

Energy uses of 100kVA or greater and all major water uses are sub-metered and managed through an efficient energy management system. Upgraded roofing insulation will improve the indoor thermal comfort and reduce the amount of energy used for building cooling; and internal blinds have been specified on all windows to reduce daylight glare. A total overhaul of building mechanical, electrical and wet services has improved energy efficiency. The outdated mechanical equipment was replaced by a VRF system, improving the system COP and general performance. In addition, hot water for amenities is heated using a heat-pump, thus improving efficiency and saving electricity.

Occupancy sensors were positioned throughout the circulation and common areas as well as bathrooms and storerooms, and energy efficient lighting was installed throughout the building. The lighting design was also updated to include efficient luminaires that provide appropriate lighting levels with much reduced energy consumption.

Potable water consumption has been significantly reduced through the installation of dual flush and low flow sanitary fittings, and rainwater harvesting for toilet flushing. Waste collection and recycling is being undertaken by waste and recycling service providers, with measures being put in place to improve the rate of recycling – such as the provision of confidential paper bins for white paper; flattening and storing of cardboard boxes; and the separation of wet waste (mostly from the canteen) from recyclables and landfill.

To inform occupants and users of all the building’s incorporated service and management systems, a Building User Guide was compiled, and educational material has been provided on a screen in the building foyer to communicate water and energy consumption data with occupants. This will enable the facilities management team to optimise the building’s environmental performance and minimise its environmental impact; and will go a long way to ensuring that all future alterations, additions and program changes are consistent with the intent of the purpose of the Building Users’ Guide and the health of the environment.

Compion explains that there were a few challenges in the Green Star certification process.

When working with an older building, with no physical extensions or additions and alterations, there was no room for targeting points through innovation. There were also some challenges in getting all the existing building information from old drawings. And logistically, the tenants remained in the building during construction so the refurbishment had to happen floor by floor, which made the process relatively slow and caused some discomfort to the building users at the time.

That being said, we are looking forward to see many more refurbishment projects in the future and hope that clients can make the leap to think of the sustainability of their building projects early in the design process. This is one important way in which we will be able to reduce overall construction sector impacts, and further revitalise inner cities.

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