Campus District Cooling (CDC) System - Averting an Energy Crisis

In 2008, JCU's Townsville Campus was facing an energy dilemma. It had reached a point where its energy demand was close to that of the available supply. Thus, it could no longer expand its operations without major infrastructure upgrades to the electricity supply or a major rethink of its energy efficiency.

It was identified that air-conditioning was a major consumer of electricity, using close to 60% of the total energy for the campus. Each building had its own air-conditioning plants, and many of these were inefficient, outdated and in need of replacement.

Instead of upgrading the electricity infrastructure to meet the growing demand, the University decided to pursue energy efficiency as the solution to the growing campus. This was a more sustainable approach and looked at a long term solution for the University.

The CDC system provides chilled water (4^oC) to most of JCU's buildings through a network of underground pipes. This chilled water provides highly efficient air conditioning to the buildings it supplies.

The water is cooled at night using large chillers and then stored in a large steel tank measuring 17 metres high and 30 metres in diameter.

JCU's Townsville Campus has the largest CDC tank in the Southern Hemisphere, holding 12.5 million litres of water.

Water is chilled at night for several reasons:

Peak demand

Electricity is charged on both energy consumed and the peak demand. Peak demand is the peak energy use for each month and can increase charges significantly. Traditionally for JCU, peak demand occurs during daytime periods, when lighting, air-conditioning and other power uses are all occurring at the same time. By taking out the air-conditioning portion of this, the daytime peak demand is reduced significantly (up to 40%).

Cooler temperatures

Cooler night time temperatures mean the chillers don't need to work as hard to chill the water than during the day, resulting in efficiency gains.

Due to the success of the Townsville system, a 9ML tank and central cooling system were installed in Cairns in 2012. Many of the lessons learned from the Townsville CDC system were used to improve the efficiency and usability of the Cairns system.

These systems have helped to reduce JCU’s electricity costs by over $3 million per year.