Investa | 259 Queen Street | Case Study

Background on Investa 259 Queen Street, Brisbane.

Investa partnered with Bueno across its office portfolio in 2019, entrusting Bueno to manage DLP projects, NABERS and GRESB data inputs as well as reaching ambitious target towards Net Zero.

259 Queen St had achieved a 5 star NABERS energy rating but now required further improvement as new regulations for government tenants seeking a 5.5 star energy rating.

A focused and collaborative approach from Investa and the site teams saw improved NABERS energy, despite the hot 2024 summer.

The Challenge

In 2024, Australia experienced a much warmer summer than previous years. One metric used to measure this is “Cooling Degree Days” (CDD). Queensland experienced a 30% increase in CDD during 2024 summer compared to 2023. As a result, many buildings and portfolios expected increases in cooling operation and costs associated with the cooling demand increase.

The Journey Begins

Bueno adopted a systematic approach to enhancing operational efficiencies across each asset. The team at 259 Queen St, Brisbane exemplified proactive engagement, collaborating closely with Bueno’s Building Performance Specialists to implement identified optimization strategies and seize savings opportunities and defy the hot summer trends. Their efforts directed towards reducing utility consumption, enhancing tenant comfort, and curbing emissions.

The Summary

Numerous A-grade office towers across Australia saw an increase in energy consumption during the summer of 2023/24 compared to the previous years. 259 Queen St bucked the trend with a notable reduction of -4.5%. This achievement was made possible through the implementation of Bueno’s recommended actions, along with the site teams’ dedication to playing their part in achieving Investa’s energy efficiency goals.

Conclusion

259 Queen St, Brisbane is tracking over 5.5 stars NABERS Energy, and with Bueno continuing to monitor and analyze all systems will continue to improve. This great result was achieved through Bueno’s platform; uncovering improved efficiency opportunities that an engaged and committed Investa site team aligned with to improve tenant comfort and retention and NABERS Energy uplift.

Results

Bueno’s Performance Services team utilized The Bueno Platform and their extensive site knowledge to create several effective strategies to reduce electricity consumption.

Chilled Water System (CHWS)

Bueno discovered the chilled water plant overshooting pressure and temperature set points, causing excessive energy consumption and tenant comfort complaints.  Site teams were engaged and found faults with a pressure sensor and Chiller controls strategy.  Prompt rectification achieved savings of:

Electricity savings 11,500 kWh / pa

Financial saving  ~ $2,300 pa

Tenant Condenser Water System (TCDWS)

A review of the sites’ highest energy-consuming equipment found that the tenant condenser water systems would benefit from the installation of variable speed drives (VSD). A VSD controlling with a differential pressure sensor reduced pump energy consumption by 45%, 24 hours a day. This optimization strategy alone saw significant site improvements of:

NABERS energy +0.04 stars

Electricity savings 70,000 kWh / pa

Financial saving  ~ $11,000 pa

Cooling Tower Systems

Cooling towers are required to reject heat, and often run after hours to support comms room units and 24 hour operation centres. The fans for heat rejection were found to be unnecessarily running at high speeds overnight.  An afterhours temperature reset was implemented, resulting in savings of:

Electricity savings 68,000 kWh / pa

Financial savings ~ $11,000 / pa

Further savings were achieved by changing the cooling towers’ fan controls logic to run both fans in parallel.

Electricity savings 28,000 kWh / pa

Financial savings ~ $5,500 / pa

Zone Temperature Control

Bueno observed that the base building variable air volume (VAV) heaters were running during summer, with ambient temperatures over 30 degrees, as a result of tenant AC units excessive cooling. The tenant AC units were cooling the base building zone temp sensors, imitating a heating demand. A 4pm lockout and an outside air lockout was introduced to all heater enables, as well as adjusting the tenant AC set points. Tenant comfort was drastically improved and achieved savings of:

Electricity savings 17,500 kWh / pa

Financial saving  ~ $3,500 pa