NERSA Kulawula House is in the heart of Pretoria’s inner city and has been home to the regulatory authority since the building was constructed in 1982. “Choosing an existing building over a new building has major implications,” says accredited professional Zendré Compion of Solid Green. “There is an obvious attraction to starting a design project with a clean slate in a new precinct or developing area, but as we know, the impact of construction, associated waste and sprawl is huge.
GBCSA awards Green Star points to refurbishment projects for exactly these reasons – points are given for reusing the building structure and façade, as well as reuse of land. Credits for topsoil and contamination of land are excluded where they are not impacted by an existing building, and the material credits also fall away (timber, concrete, steel) as the material value is less than 1% of the contract value. This rewards the project through a slightly simplified set of criteria.”
Compion says that while older buildings may be a challenge on some fronts, another benefit to refurbishment is that many older structures incorporate good passive design principles, which slowly fell away when building thermal comfort started being managed by automated systems. “These older buildings, like Kulawula House, have smaller glazed elements, large overhangs, external vertical blinds where the afternoon summer sun hits the building, and narrow floor plates.”
Given that the building is now more than 35 years old, a focused refurbishment was necessary to bring the building fabric and services up to date. This meant upgrading to and complying with the latest technology, standards, regulations, and codes, while also addressing the building’s current and predicted future requirements. The team targeted Indoor Environmental Quality (IEQ), Energy (ENE) and Water points, all elements that form the core of a major systems refurbishment. “As we were working with an older building, with no physical extensions, additions or alterations, there was no room for getting points for innovation,” explains Compion. The team faced some challenges such as getting all the existing building information from old drawings, as well as working around the tenants who remained in the building throughout. The office is split across eight floors and so refurbishment had to happen floor by floor, which made the process relatively slow and with obvious discomfort to the building users at the time, recalls Compion.
A green approach
To attain Kulawula House’s 4-Star Green Star Office v1.1 As-Built certification, a comprehensive set of sustainability features were put in place. The energy of the building was modelled using the as-built building and systems information and compared to a notional building model, and the refurbished building showed an improvement in operational energy consumption of 42% over the SANS standard.
Sub-metering was provided to facilitate ongoing management. The lighting power density for artificial light was limited to a maximum of 2.0W/m² per 100 lux, and energy efficient lighting was installed throughout.
Some water initiatives included making use of dual-flush and low-flow sanitary fittings to reduce potable water consumption, rainwater harvesting (re-used for toilet flushing), and the installation of water meters and an automated monitoring mechanism. The building’s discharge to sewers has been reduced by 50% against an average practice benchmark due to the reduction in potable water use. Water for use in the canteen kitchen is heated using a heat-pump. The building also saves energy by not including hot water in the ablution facilities.
Some of the environmental aspects that were tackled to enhance occupant wellbeing included upgrading the roof insulation for improved thermal comfort (which also reduces energy required to cool the building), as well as using heat-pump chillers on the roof to keep the building warm during winter and cool during summer. This equipment produces hot and cold water that air conditioning units in the ceilings use to blow cool or warm air into the office spaces, depending on the temperature setting. Fresh air is provided to these units from a fan on the roof, at a rate of 12.5l/s/p, which exceeds conventional standards. Internal blinds are used on all windows to reduce daylight glare.
The NERSA Kulawula House has two waste storage areas, and a recycling and general waste contractor picks up the waste frequently. Through monitoring and reporting on the waste produced each year, waste targets can be established. The building should aim to reduce its overall waste by 10% and improve its recycling rate by 5% per year.
Located in Arcadia, the building is well connected to local amenities and existing public transport infrastructure. Parking for occupants is provided in the basement, with preferential parking indicated for electric and car-share vehicles.
Andre Wright, director at Boogertman + Partners, architects on the project, describes the NERSA Kulawula’s design concept: “The aim was to transform the outdated, non-descriptive space into a space of creativity, energy and vibrance through the use of colour and graphics. We stripped, cleaned and repainted the interior of the building to create a neutral shell, with dedicated graphic walls to navigate the user through the buildings. The idea of energy was used in these graphics and decals, and the interior used all the colours of the NERSA brand dedicating certain colours to various functions. For example, pause areas were a cool blue, to promote relaxation. The circulation spaces were designed to envelop movement and flow.”
According to the Centre for Development and Enterprise (CDE), 70% of South Africa’s population will be urbanised by 2030, with more than 60% urbanised already. While South Africa’s traditional approach to commercial and residential development has given rise to enormous and unsustainable urban sprawl, building owners and developers are in a unique position to carefully manage growing densification to prevent urban decay, which is what we are currently seeing in traditional CBDs.
“Kulawula House is an excellent example of how upgrading an existing building in the inner city can contribute towards the revitalisation of our traditional hubs, and I hope that many more of our clients will consider this kind of refurbishment,” says Compion. Inner cities are multi-sector economies that, when managed well, attract pedestrians, commercial activity and reliable tenants while stimulating new businesses. “With so much existing infrastructure, it makes sustainable sense to work with what is already there, rather than focusing on new builds. This has a significant effect in reducing one’s construction impact and contributing towards greener future cities.”