The 13-storey office tower at 108 King William Street has undergone a major HVAC transformation. By replacing obsolete constant volume systems with patent-pending electronic VAV Helical Vari-Swirl™ Diffusers and the patent-pending Vari-Smart™ Control System (VSCS), the 1972 building now leads in tenant adaptability, indoor air quality (IAQ), and energy performance.
Engineering Highlights:
• Precision IEQ Sensing: Each ‘Works with WELL’ certified Vari-Swirl™ diffuser comes with inbuilt room temperature, supply air temperature and pressure sensors. Optional onboard PIR, RH, and CO2 sensors tighten control and extend VAV turndown.
• Scalable BMS Integration: The VSCS architecture manages 4 AHUs, controlling fan pressure, supply air temperature, and dehumidification. It seamlessly coordinates 24 pairs of corner office supply source dampers, 52 motorised floor take-off pressure dampers and 64 reheat coils, based on inputs from 344 Vari-Swirl™ diffusers.
• Energy Optimisation: Real-time static pressure optimisation and supply air temperature resets reduce fan energy, extend free-cooling and minimise reheat operation to drastically slash power use.
The Bottom Line: Vari-Smart™ adaptive AHU tuning and Vari-Swirl™ diffuser management actively optimise supply air temperature and low-pressure operation – system wide and localised – and control localised VAV and IEQ-based DCV turndown. Comfort and IAQ are directed where required and power consumption is minimised, enhancing comfort and wellness, maximising adaptability to future tenancy changes, futureproofing against global heating, and driving the building towards its engineered design objective of a 5-star NABERS Energy rating.










































