GREENPEACE activists have staged an hour-long rooftop protest at computer giant Apple's European headquarters.
The group aims to raise awareness about the growing use and scale of cloud data centres which store information for customers and companies at a central base housing thousands of computers.
Kumi Naidoo, Greenpeace International executive director, said customers of some of the world leading IT and internet companies want to know the companies' energy policies are sustainable.
"When people around the world share their music or photos on the cloud, they want to know that the cloud is powered by clean, safe energy," he said.
A number of protesters scaled the Apple building in Holyhill at around 7am and voluntarily came down after an hour.
Gardai and the fire service were called to the scene and other activists distributed leaflets to staff.
Greenpeace, which praised Apple's energy policy in Ireland, also staged protests over cloud computing centres in Turkey and Luxembourg. It is angered over the use of coal generated energy for new cloud sites.
Iris Cheng, campaigner from Greenpeace International, said some major IT companies are not innovative enough about how they power their centres.
"Coal is one of the dirtiest fuels on the planet, causing untold damage to the environment and global climate," she said.
"A company that prides itself for its vision and innovation should not be using outdated polluting coal.
"The irony here in Cork is that Apple's HQ is powered by renewable energy sources. The much needed jobs this HQ provides to the local community are also increasing the jobs in the Irish renewable energy sector. Apple has shown it can power with clean energy in Cork, it is now time to clean up globally."
Ireland is increasingly becoming an important base for cloud computing with the Government and investors highlighting the cool climate and westerly weather patterns as a big draw.
The units house thousands of computers and consume huge amounts of electricity with Greenpeace claiming some can use as much electricity as 250,000 European homes.
The report, How Clean is Your Cloud?, found that if the cloud were a country its electricity demand would rank fifth in the world and is expected to triple by 2020.