Tshedimosetso House boasts the continent’s first building integrated solar facade, which makes it a base of ongoing research into this technology.
The initial brief for the new Government Communications and Information Systems (GCIS) building in Hatfield, Tshwane was for a standard commercial office design. But it has evolved into a workplace that aims to showcase world-class green technology while keeping in mind historical preservation and urban integration.
The porticos of the old 1930s “post office” houses – demolished to make way for the new office – were preserved and became part of the fabric of Tshedimosetso in a nod to its history. No longer placed behind boundaries and fences, the building interacts with people, notes Growthpoint sustainable development manager Werner van Antwerpen.
SNA Architects owner, Beyers Slabbert, points out how the building’s colour and strong, bold lines make it a prominent, African-inspired asset.
The balconies along the edge of the building allow for an element of interaction with the street life, while a delicate level difference at the main entrance, prominent on the corner of Festival and Francis Baard streets, establishes a clear distinction between public and semi-private, says Melissa Appelgryn, interior architect at SNA Architects.
Importantly, “the new building proves that government is working towards vision 2030 and making sure the GCIS plays its part in conserving energy and water,” says GCIS acting CEO Phumla Williams.
The solar-enabled facade of Tshedimosetso House is the major talking point among sustainability enthusiasts. Building integrated photovoltaics (BIPV) replace conventional building materials.
At Tshedimosetso, after much convincing from the team led by electrically-minded Peet Botha from Conscius Electrical Consulting Engineers, a decision was made to test the latest PV technologies available.
Two different types of power-generating glass, never before tested in Africa, have been incorporated. One is E-Glass windows, which contain blue crystalline PV wafers within the glass. The other is the clear Tropiglas solution, which contains a nanotechnology polymer, sandwiched between two layers of glass.
The micro- and nano-particles interact with visible light, and ultraviolet radiation is converted to longer wavelengths, scattering infrared light to the edges of the glass. PV cells along the edge of the frame collect the infrared, enabling the transparent glass panel to produce electricity. Tropiglas also reduces heat gain and blocks damaging UV and infrared light, outperforming double-glazing.
The 16.8kW system is expected to deliver an energy consumption saving of up to 25% during normal office hours. In the summer, the system generated more than its peak design capacity – up to 21kW.
Since the BIPV is relatively expensive, the project proceeded with as much of it as was economically feasible, and monitoring the glass’ performance has become a broader research project. Botha says the PV project is an incubator and laboratory providing the opportunity to practically measure the scientific engineering parameters required to make sound technical and financial decisions. Thanks to the research nature of the project, the professional team was able to procure the BIPV’s at cost from Tropiglas Technologies and current indications show a much shorter payback period for the system compared to conventional photovoltaic systems.
The research project is headed by Prof. Jan-Harm Pretorius from the University of Johannesburg (UJ) and is linked to Edith Cowan University in Australia.
The system can be monitored remotely and UJ visits the site monthly, producing quarterly reports. The reports compare the two types of BIPV, as well as account for how the various zones on the different sides of the building perform, with differing orientation, height and interference of objects such as trees.
The results from the first year’s research are expected in November 2014, and could become the strategic model for future implementation of cost-effective integrated PV panels in South Africa.
Slabbert says there has been a significant loss of performance due to the angle of the panels, but this is an area where learning means that solutions can be developed to overcome this in future.
The DC output from the PVs are fed through an inverter, directly into the building’s internal grid.
The system’s cost is significantly reduced because no battery bank is required.
Appelgryn notes that the PVs add an aesthetic appeal inside the building as their reflection is seen in the internal space. This constantly reminds occupants of their role in energy saving within the context of Eskom’s 49M energy efficiency campaign.
Slabbert says convincing the owner, developer and tenant to implement the BIPV was no easy feat. They wanted to be sure of the potential impacts on the tenants, and a walk-in mock-up of the site was built.
Managing perceptions was important, and what ultimately sealed the deal was that this building would be positively contributing to something that is a global issue, concludes Slabbert.
The full feature appears in the October – November 2014 issue.