When people say "it's saved to the cloud," they say it as if the data is floating somewhere vague and ethereal. It isn't. Your photos, messages, bank details, and streaming videos live in very real, very large buildings full of humming computers. Those buildings are called data centres.
What's inside
A data centre is essentially a warehouse stuffed with servers — powerful computers designed to run 24 hours a day, 7 days a week, for years at a time. These servers don't have screens or keyboards; they're just metal boxes packed with processors, memory, and storage, stacked in tall racks like shelves in a library.
A large data centre might contain hundreds of thousands of servers. Companies like Google, Amazon, and Microsoft run some of the biggest, each the size of multiple football pitches.
Think of a data centre as a giant post office warehouse where instead of parcels, it stores information — and instead of sorting and delivering letters, it processes requests: "send this email," "load this webpage," "stream this video." Every time you do anything online, it's almost certainly a request going to a computer in one of these buildings.
The cooling problem
Computers generate heat. Lots of it. Pack a hundred thousand computers into a building and you have an extraordinary amount of heat to get rid of — otherwise the equipment would overheat and fail. This is why data centres spend enormous amounts of energy on cooling systems: industrial air conditioning, cold water pipes, and in some cases actually building near cold rivers or in cold countries (Iceland is popular for this reason).
The environmental cost
Data centres currently consume around 1-2% of global electricity — a figure that's growing rapidly as more of our lives move online and as AI systems (which are extraordinarily hungry for computing power) become more common. Tech companies have made big promises about using renewable energy, and many are making genuine progress, though the sheer scale of energy demand remains a challenge.
Where are they?
Data centres are often built in areas with cheap electricity, good internet connections, and cooler climates. The UK has a large cluster in London and the South East. You've almost certainly driven past one without knowing — they tend to look like anonymous grey warehouses with no windows and a lot of security fencing.
When people say "it's saved to the cloud," they make it sound like your data floats in the sky. It doesn't. Your photos, messages, bank details, and videos are stored in real, very large buildings. These buildings are full of humming computers. They are called data centres.
What's inside
A data centre is like a huge warehouse packed with servers. Servers are powerful computers that run all day and all night. They never switch off, even on weekends or holidays. These computers do not have screens or keyboards. They are just metal boxes full of parts that store and process information. They are stacked in tall rows, like books on library shelves.
A big data centre can hold hundreds of thousands of servers. Companies like Google, Amazon, and Microsoft run some of the largest ones. Some are as big as several football pitches put together.
Think of a data centre like a giant post office warehouse. But instead of storing parcels, it stores information. Instead of sorting letters, it handles requests like "send this email," "open this webpage," or "play this video." Every time you do something online, a computer in one of these buildings does the work.
The cooling problem
Computers get hot when they work. Now imagine hundreds of thousands of computers in one building. That creates an enormous amount of heat. If the heat is not removed, the computers would break. Data centres use huge cooling systems to fix this. They use industrial air conditioning and cold water pipes. Some data centres are even built near cold rivers or in cold countries. Iceland is a popular choice because it is naturally cold there.
The environmental cost
Data centres use a lot of electricity. They currently use around one to two percent of all the electricity in the world. That number is growing. More people are going online every year. AI computer systems also use huge amounts of power. Many big tech companies have promised to use cleaner energy like wind and solar power. Some are making good progress. But the amount of energy needed is still a big challenge.
Where are they?
Data centres are usually built where electricity is cheap and the weather is cool. They also need strong internet connections. In the UK, many are found in London and the South East. You have probably driven past one without noticing. They look like plain grey warehouses with no windows. They usually have lots of security fencing around them.