It may be business as usual for the tenants of Upper Grayston Office Park Block F but their office building could become a showcase of green building “world leadership” if it receives a 6-Star Green Star SA As-Built rating – bypassing the conventional design rating and proving this professional team built progressively block by block.

Upper Grayston Office Park Block F, enveloped by Ann Crescent, was designed and built by the same professional team responsible for the entire development. In an exceptional example of incremental improvement, the team applied all the lessons learnt from each building to improve the next.

Upper Grayston Block E was the first in the office park to pursue a Green Star SA rating. In November 2011, Block E received a 4-Star Green Star SA Office v1 Design rating with 55 points. As this was just five points short of a 5-Star rating, the project team decided to target a 5-Star Green Star SA Office v1 As-Built rating with Block E and achieved this in October 2013, with 67 weighted points.

In Block F’s initial design development phases, developer Ron Henderson of Brydensgroup wanted to investigate the possibility of a 6-Star rating.

Working off the foundations set by Block E, the project team is confident a 6-Star As-Built rating is possible, bypassing the usual design rating. The Green Star strategy for Block E was updated to include the commissioning and a solar PV system.

 6-Star appeal

To achieve a 6-Star rating, the team is aiming for five innovation points, which are only added after the weighted score. Extra points can be earned for taking into account credit Eco-05: Urban Heat Island. This credit recognises and rewards initiatives to reduce the heat island effect on buildings, which impacts on microclimates, human and wildlife habitats.

In this case, the use of a lighter shade of concrete, which absorbs less heat than ordinary concrete, could earn the team two extra points.

Another point in this category could be earned for the Green Star SA Accredited Professional Team.

One innovation point could be earned for including stairs in the building. The display of live metering data in the foyer could make up a fifth innovation point.

Live metering display

Most green buildings have energy and water meters installed to monitor usage and indicate problems or leaks. Block F has gone one step further.

“We found that while meters are typically specified at high resolution for green buildings, they are seldom used and the valuable information they collect is not accessible to building users,” says Warren Gray of Solid Green Consulting.

To remedy this, the company has developed a simple way to connect users to their energy and water use so they have a means to control usage and set targets.

“The information was already on the web via the metering system for Block E, so we built a system to display this data and load it onto the screen in the foyer,” says Gray. “We then developed it further to automate the billing of each tenant – and to do so very accurately so that tenants pay for what they use and not a pro-rata amount.”

Rainwater harvesting, treatment and reuse

Rainwater is captured from the roof and collected in a 5m³ rainwater storage tank. From there it is filtered and treated to potable water standards and pumped into storage tanks on the roof.

Harvested rainwater is used for toilets, shower and taps.

Municipal supply water is only used when the rainwater has been depleted. Hot water, generated through a solar panel system, is circulated.

PV system

Fifty-three square metres of photovoltaic (PV) panels have been installed on the roof, designed to meet 15% of the building’s peak demand at its highest production.

Over a yearly cycle it is expected to provide 15 000kW, around 10% of the building’s energy requirements. The system has no battery to store energy and works by first drawing energy from the panels before using the mains power connection to meet demand.

Tenant buy-in

Although these features are designed to save water and energy, their effectiveness depends on tenant behaviour. This project differs from other developments that pursue a Green Star SA rating in that it is a commercial property designed without a particular tenant in mind. In most (larger) buildings that have achieved Green Star SA rating, the building was designed with the tenant in mind and usually this tenant was already committed to green policies.

Once suitable tenants have been found, Henderson says a hand-over meeting explains the operation of the building in the context of the Building Users Guide. “Thereafter we monitor energy usage and point out anomalies.”

Integrated fit-out

The project has not yet been submitted to the Green Building Council of South Africa (GBCSA) because of the integrated fit-out. The team decided to deliver the building as an integrated fit-out, where tenancy design and construction are fully coordinated with the base building design and construction, as it is more cost effective and environmentally sustainable.

Brown, together with the green building consultant, is monitoring this process. “The tenant brings in a designer and they need to be brought up to speed with the green requirements regarding the fit-out,” says Brown.

The building is currently 70% occupied, but needs 100% occupancy in order to rate the building.