Data centres are big, expensive buildings
Why? Power and cooling equipment — and lots of it. The plant, not the floor, is what makes a data centre big and costly.
Data centres are big, expensive buildings. Why? Power and cooling equipment — and lots of it.
The power and cooling demands are extremely high, and they run 24/7/365 with built-in redundancy. That demand is driven by the data hall: the more servers you pack into racks, the more heat they throw off, and the more cooling and power you need to keep the building running.
Redundancy multiplies the plant
On top of that, data centres build redundancy into their systems, so that if one fails another keeps things running while it is repaired — typically:
- 2N — e.g. two generators each sized for 100% of the load; if one fails, the other starts.
- N+1 — e.g. three generators each at 50% of the load, two running; if one fails, the third comes on.
The result is a building with a relatively small useable area — the data hall — and a large plant area full of generators, chillers and UPS systems.
A comparison
Compare a 1,000 m² office with a 1,000 m² data hall (approximate figures, based on South African construction costs). In an office, mechanical and electrical plant takes up 6–10% of the area — about 100 m² for our office. In a colocation data centre, the plant area for a 1,000 m² hall is around 1,000–1,500 m². That is roughly 10–15 times the plant of an office.
Because the plant is so large, it dominates the cost too: around 80% of the cost of a data centre is plant, versus 20–25% for an office. Two things follow — the plant equipment is the major driver when costing a data centre, and because that plant is bought on the global market, data centre construction costs are heavily influenced by global costs and trends.