The Department for Environment, Food and Rural Affairs (Defra) will start to roll out Microsoft's Windows Vista operating system from June.
The deployment will cover 10,000 computers and is expected to be completed by the end of the year. The cost of the rollout is covered by an annual service agreement with IBM.
Although it's unclear if Defra is the first central government department to commit to a Vista deployment, it is among the early adopters.
According to Defra, Vista's power-management features will help reduce the department's carbon footprint while the BitLocker encryption system will boost security.
In a parliament-written answer earlier this month, Jonathan Shaw MP, parliamentary under secretary of state at Defra, said Vista's hibernating feature — where it powers down when not in use — could potentially save around £20,000 in energy costs per year.
Shaw added the department was looking at the NightWatchman power-management technology from 1E, a Windows systems-management software and services firm. However, the department has put this on the backburner until the results of the Vista rollout are known.
The Vista upgrade is part of a regular technical refresh of Defra systems and was chosen over XP to avoid another near-term upgrade, saving time and resources.
Speaking to ZDNet.co.uk's sister site, silicon.com, Mike Haigh, government marketing manager for Microsoft in the UK, said: "We've actually got a number of [central] government departments deploying or planning to deploy Vista."