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District Cooling

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


In 2008, JCU's Douglas Campus was facing an energy dilemma. It had reached a point where its energy demand was close to that of the 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 Each building had its own air-conditioning plants, and many of these were inefficient, outdated and in need of replacement.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.

JCU's Cairns Campus had already installed a CDC system and it had been successful in reducing energy use while providing efficient, reliable air-conditioning to the campus.

What is the CDC system?

Basically, the CDC system provides chilled water (6oC) to most of JCU's buildings through a network of underground pipes. This chilled water is then provides highly efficient air conditioning to the buildings it supplies.

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

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

For a more detailed explanation of the system click here (external link).

Why do we chill the water at night?

Water is chilled at night for several reasons:

Off peak charges

The cost of electricity is lower during off-peak (11pm - 6am); therefore considerable savings can be achieved by running chillers at night instead of the traditional air-conditioning units that work through the day.

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.

Working together to achieve energy savings

JCU is working closely with Ergon Energy to realise energy savings and demand reduction at the JCU Douglas site.

JCU and Ergon have signed an MOU stating that JCU will reduce its maximum demand by 4.5MW over the next 5 years and will receive $200,000 each year if it does so.

This means everyone is a winner as it negates the need for Ergon to upgrade the electricity supply infrastructure to JCU and save JCU money by reducing its energy use.

Ergon has produced a Network Demand Management Case Study highlighting the benefits of the CDC for JCU and Ergon.

(Reference: http://www.jcu.edu.au/tropeco/sustainatjcu/energy/JCUPRD1_070531.html (external link) )

Contributors to this page: jack.shao372 points  .
Page last modified on Monday 15 of August, 2011 23:14:45 EST by jack.shao372 points .

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