Norway's Green Mountain Data Centre - which comes with a tagline of 'Greenest Data Centre in the World’ and sits underground in a former NATO facility - has signed an anchor tenant.

The new follows the announcement that the 21,000 sq m Green Mountain Data Centre is now under construction and will be fully operational at a Tier III standard in Q1 next year.

A major Nordic IT Company has signed up to be Green Mountain's first customer.

Green Mountain said it took months to sign its first customer due to the complex nature of the customer's requirements, especially in the areas of data center design and commercial elements.

Green Mountain CEO Knut Molaug said, however, that having a first customer was a key moment for the data center operator, which in the end was selected because of "the high security of the facility, its low operational costs and its green credentials".

"For Green Mountain this is a key moment as we view this as market acceptance of our data center," Molaug said.

"We are in negotiations with several other local companies but as it will be one of the largest facilities of its type in the Nordics. . .We also wish to attract large environmentally aware multinationals to the data center who wish to lower their operating costs and carbon emissions, good connectivity enables us to do that."

Green Mountain Data Centre is a multi-million pound development funded by the Smedvig family.

Part of its green credentials are down to its planned use of hydropower, removing all carbon emissions.

Overall, Molaug said the 20MW data center will have about 76,000 tonnes less CO2 compared to US and UK facilities.

It is also using heat from the servers to cool the water used in the data center, which comes from a nearby fjord.

Norway is also known for its cheap energy costs - about 40% less than in the UK, according to Molaug.