The institution joins a growing number of firms aiming to improve their green credentials by using energy from renewable sources.
Commenting on the switch, Martin Pascoe, RIBA head of property and facilities, said: "RIBA has adopted a robust climate change policy.
"We have implemented many projects to address our corporate behaviour and reduce our own environmental impact, and are therefore delighted to have switched to Green Energy UK."
According to Green Energy UK's chief executive Doug Stewart, the construction sector has a large part to play in helping the government meet its carbon emissions targets.
He said reducing energy consumption is the best way to cut greenhouse gas emissions.
Recent government figures show the UK has achieved an 8.5 per cent reduction in carbon emissions when compared with figures from 1990 11.5 per cent less than its 2010 target.
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