Bendigo Bank will double its data centre compute capacity by virtualising its blade servers and installing new mainframes, and is saving more than $375,000 a year by being more energy efficient with an enterprise-wide green renovation.

The IBM z9 mainframe servers are housed in a new AUD$10 million data centre which will handle the bank's entire network, including 332 branch offices and the new head office, which attained a five-star green rating for its design.

Bendigo Bank strategic solutions senior manager Leigh Watkins said the bank began to aggregate and consolidate its energy costs about four years ago after audits revealed money was being wasted through multiple energy suppliers and excessive power consumption.

"We realized that keeping our old desktop boxes, CRT monitors, and printers constantly turned on for 118 hours a week was costing us AUD$375,000 a year," Watkins said.

"It was part of a plan to aggregate all of our energy suppliers because we had a different one for each of the sites that we had at the time. We had to pull it all together to see what savings we could generate."

The new head office holds more than 1000 staff previously spread across different sites, and has under-floor air-conditioning, solar heating, atriums for natural light, external blinds which track sunlight, louvres for natural airflow, rainwater tanks and black-water recycling.

According to Watkins, the internally managed data centre missed out on the latest power-saving cooling systems because "IT were not engaged in the thrust of the green initiative".

"We will either reduce power consumption or we will get more processing from the same amount, because we will improve air-conditioning, load and everything else," he said.

"IT wanted equipment to stay running for many different reasons but the time for devices to always run just for convenience is past, and we need to look at reducing carbon consumption."

A spokesperson for the bank said devices are intentionally left on overnight to allow software updates out of business hours.

The bank's IT department rejected using bio-diesel to fuel data centre generators because compatibility could not be guaranteed, which could jeopardize certification by the Australian Prudential Regulatory Authority (APRA).

While migrating active data from the blade servers to the mainframes is the most difficult challenge for the bank, Watkins insists it will reduce power costs because the z9s have twice the capacity.

An internal audit of power consumption using a Power-Mate energy monitor triggered the project when it found the power-saving features in the bank's desktops and peripherals did not work.

However, most devices are now capable of running in a power-saving mode following a recent IT hardware refresh.

The bank is the first of its kind to use 50 percent renewable energy green power across all sites and it has developed its own emission offset product for its customers.

Watkins said the financial benefits behind carbon reduction will amplify as energy bills rise due to government plans to factor carbon costs into the price of power.

He said power consumption can be reduced by replacing desktops with laptops.

The data centre is expected to cover the bank's IT requirements for the next 15 to 20 years.