AIR-conditioning is a key contributor to the British Library's £20m Yorkshire depository designed to protect 7 million of the UK's written works.
Based in Boston Spa near Leeds, the warehouse's air conditioning will ensure 52.5% humidity (plus or minus 5%) will preserve and protect a steady temperature and minimise the risk of damage to printed items.

Its oxygen levels will be regulated to between 15.8 and 16.2% and the whole warehouse will be sealed to protect its contents.

Scheduled to complete next year, the warehouse will house hardly-read books, journals and magazines. A reader's request will result in a published work being released from the sealed building to make its way to London's British Library.

The British Library by law must receive a copy of everything published in the UK and with up to 100,000 books published in the country each year, a home must be found to store the growing number of printed documents.