Property Australia

Rhodes Central’s crowning glory

Karen Jamal Karen Jamal September 21, 2021

The glittering golden jewel that crowns Billbergia’s 39-storey tower at Sydney’s Rhodes Central is not just eye-catching. It is also a world-leading heliostat that reflects sunlight onto the spaces below.


  Why we love this project:

  • Billbergia’s Rhodes Central heliostat is one of only two in the world to sit atop a mixed-use development; the other is Frasers Property Australia’s One Central Park, also in Sydney.
  • The 27-metre-high heliostat – from ‘helios’ meaning ‘sun’ in Greek and ‘stat’ as in stationary – features a series of custom-made smart mirrors.
  • The mirrors autonomously shift and tilt towards the sun and then reflect sunlight onto the otherwise overshadowed Union Square Plaza below.


Billbergia Group’s $2 billion Rhodes Central precinct will feature a striking golden heliostat that will set the 39-storey tower at 14-22 Walker Street soaring to 145 metres.

While heliostat technology has been around for some time, most are used in solar plants “in the middle of the desert,” says Alex Lehmann, research scientist at Heliosystems and designer of the Rhodes Central heliostat.

“It’s only very recently that they’ve been adapted for this kind of architectural use, and we are only just beginning to understand what you can do with active and passive lighting in our cities.”

As buildings get taller, new options are emerging to direct light to public spaces on the ground. Lehmann says this “latest generation” heliostat is one for developers to ponder as they “think about lighting in public spaces”.

The heliostat is a collaboration between HeliostatSA, SJB Architecture, Inhabit Technical Design and Samaras Engineering.

The Rhodes Central heliostat is made up of several complex parts. The striking golden crown is made from high-quality structural steel wrapped in gold-coloured, solid aluminium panels.

A network of sun-tracking motorised mirrors – invisible to street dwellers – follow the sun’s movement during the day. Sunlight bounces from these mirrors to a second set of reflector mirrors in the golden crown that then direct the sunlight towards Union Square Plaza. Special plastic sheeting covers the reflective surface and filters out harmful UV light.

The project team installed a weather station on the roof that monitors wind and weather conditions, and the heliostats responds accordingly. “The autonomous reflectors put themselves in a brace position if it’s windy, and if it rains, they position themselves to get a wash. If it’s hailing, they tilt themselves into a position to minimise any hail damage,” Lehmann explains.

The final touch to the Rhodes Central heliostat is a special ‘night glow’ feature that will showcase the structural design when the sun goes down.

SJB_Rhodes-Heliostat-Diagram (1)