Why Do Data Centres Use So Much Power?

Why do data centres use so much power? A data centre runs thousands of servers every hour of every day, nearly every watt those servers use turns into heat that needs more power to remove, and backup systems must be ready to carry the full load if the grid drops out. AI chips have pushed this further, because a single rack of GPU servers can draw several times what a traditional rack did, which is why data centres are planned in megawatts rather than the kilowatts of an ordinary commercial building.

⚡ Quick Answers: Why Data Centres Use So Much Power

• What uses the most power in a data centre? The servers and chips themselves, followed by the cooling needed to remove the heat they create.
• Why does cooling use so much? Almost every watt a server draws becomes heat, and moving that heat out of the building takes pumps, fans and chillers running constantly.
• Why is backup power part of the story? Batteries and generators must be sized to carry the whole site, so the supply is built far larger than the average load.
• Why is AI making it worse? A rack of AI servers can draw several times the power of a traditional rack, which concentrates both load and heat into the same floor space.
• How fast is Australian demand growing? AEMO’s 2026 forecast has data centre consumption rising from about 5 TWh a year today to about 34 TWh by 2035 to 2036.
• Where does an electrician come in? Someone has to size the cables, mains and switchboards that deliver all that capacity, and get the distributor to approve a bigger supply.

1. The servers never switch off

An office goes quiet at night. A data centre does not. Servers, storage and network gear run every hour of every day, because the websites, banking apps, streaming services and AI tools they host are expected to answer instantly at any time. A single 100 megawatt site running flat out for a year would use about 0.9 terawatt hours, which is why these facilities are measured in megawatts rather than the kilowatts we size for a typical home or shopfront.

That constant load is the first reason the totals are so large. Most buildings have a peak and a quiet period. A data centre has a high floor and a high ceiling, so the meter keeps climbing all year. AEMO estimates that the roughly 165 data centres connected to the National Electricity Market today use about 5 terawatt hours a year, and average monthly data centre demand has grown from almost 200 megawatts in 2018 to more than 700 megawatts in June 2026.

2. Every watt becomes heat, and heat has to go somewhere

Electricity that goes into a server does not disappear. Almost all of it ends up as heat, and if that heat is not removed the equipment slows itself down, fails early or shuts off. Chillers, fans, pumps and cooling towers run constantly to move heat out of the data hall, and they draw serious power doing it.

The industry measures this with Power Usage Effectiveness, or PUE. It divides the total power the whole facility uses by the power the IT equipment uses. A PUE of 1.5 means that for every 1 kilowatt reaching the servers, another half a kilowatt goes to cooling, lighting and power conversion. Traditional air cooled halls are often quoted at around 1.5 or higher, while modern liquid cooled designs are often quoted between about 1.1 and 1.2. Industry estimates commonly put cooling at roughly a quarter to 40 per cent of total power in older air cooled facilities, although the real figure varies a lot with design and climate.

3. Power is converted and lost many times before it reaches a chip

Power from the grid arrives at high voltage and is stepped down through transformers, switchgear, uninterruptible power supplies and rack power supplies before it reaches a processor. Each step is efficient, but none is perfect, and the small losses add up across a large site. Those losses also turn into heat, which loops straight back into the cooling load.

Even inside an AI facility the chips are only part of the story. Research from Epoch AI estimates that GPUs account for about 40 per cent of peak power in frontier AI data centres, with the rest going to CPUs, networking, storage, cooling and power conversion. Halving the chip power does not halve the site power, because everything around the chip scales with it.

4. Redundancy means the supply is built bigger than the average load

A data centre cannot afford an outage, so power is built with spare paths. Common arrangements are described as N+1, where there is one extra unit beyond what the load needs, and 2N, where there are two complete independent systems each able to carry everything. Uninterruptible power supplies bridge the first seconds of an outage and generators carry the site for hours or days.

This matters for the electrical connection. The supply, cables, mains and switchboards have to be sized for the peak the site could draw, with redundancy on top, not for the average. A site that uses 60 per cent of its capacity on a normal day still needs the other 40 per cent available, and a second path if the design calls for it. That is why data centre connections are large relative to the energy actually consumed. The same thinking applies to any business that cannot afford downtime, which we cover for refrigerated sites in our guide to supermarket and grocery store electrical requirements.

5. AI has pushed the density up sharply

A traditional enterprise rack has commonly drawn somewhere around 5 to 15 kilowatts. Racks built for AI training, packed with GPUs, are now commonly quoted from about 40 kilowatts up to 100 kilowatts or more. That is a jump of several times in the same footprint, and it forces liquid cooling, heavier cabling and much larger electrical distribution. Older halls often cannot take that density without new supply, new switchboards and new cooling.

The same pressure shows up in smaller facilities. A comms room or server room that sat comfortably at 10 kilowatts a few years ago can outgrow its supply quickly when a business adds GPU servers or edge computing equipment. We cover how to size a facility properly in how much power a data centre uses in Australia.

6. What it means for Australia and Sydney

AEMO’s 2026 Electricity Statement of Opportunities forecasts data centre consumption rising from about 5 terawatt hours a year to about 34 terawatt hours by 2035 to 2036, lifting data centres from roughly 3 per cent to about 13 per cent of National Electricity Market consumption. The number of proposed projects it considered more than doubled in a year, from 97 to 225. AEMO also cautions that many proposals never reach construction, so the pipeline is not a forecast of what will be built.

Closer to home, Ausgrid told a NSW inquiry that its data centre pipeline sits at 7.5 gigawatts, most of it still in assessment, and the state’s distributors warned that data centres could reach as much as 30 per cent of NSW electricity load by 2040. Endeavour Energy has floated a Western Sydney Energy Hub concept to cluster data centre connections around shared infrastructure. Each project still needs a connection approved by the local distributor. If you are not sure which one serves your site, check your network area in seconds with our postcode checker.

7. Where the electrical work sits, from server room to campus

The very largest campuses connect at high voltage. Endeavour Energy states that large or technically complex installations may be required to connect to its network at voltages from 11,000 volts to 132,000 volts, and large customers pay for the works needed upstream of the connection point. That pathway runs through the distributor’s own large customer process and high voltage design. Our Level 3 design page explains how network connection design works.

Most of the work businesses actually need sits below that. Server rooms, comms rooms, colocation suites, edge sites and existing data halls that need more capacity run on low voltage supply: consumer mains, a main switchboard, metering and the distributor’s service connection. Getting a bigger supply to one of these sites means a load assessment, a network application, larger cables, an upgraded switchboard and a carefully staged cutover. Our data centre power upgrades page covers how we approach that, and our guide to data centre power supply upgrades in Sydney walks through the steps.

Why it’s Level 2 ASP work

Increasing the capacity of the cables and mains that feed a site changes the connection between the distributor’s network and the customer’s installation. That is work for an accredited service provider, not an ordinary electrician. As a Level 2 ASP we prepare the network application, install the new mains and coordinate the connection with Ausgrid, Endeavour Energy or Essential Energy, depending on where the site is. Our Level 2 electrician page explains what that accreditation covers, and our three phase upgrade guide shows the same process on a smaller scale.

How High Demand Electrical helps

We are a licensed local team, not a call centre, and we focus on the part of the data centre story that decides whether a site can grow: the supply. That means increasing the capacity of the cables and mains going into a facility, preparing the approvals with the network, and upgrading the switchboards and distribution behind them. If you are looking for a data centre electrician near you in Sydney, we work across Sydney’s West, South West and Sutherland Shire, and we take on server rooms, comms rooms and existing data halls where more power is the constraint. For work at the highest voltages the distributor’s own process applies, and we will tell you plainly when a project sits outside what we do.

Why Data Centres Use So Much Power FAQs (Sydney)

How much electricity does a data centre use?

It ranges from a few kilowatts for a small server room to 100 megawatts or more for a large campus. Our guide to how much power a data centre uses in Australia works through the numbers.

Is cooling the biggest power user in a data centre?

The servers themselves are normally the largest share, with cooling usually the second largest. Efficient designs reduce the cooling share, which is exactly what PUE measures.

Why do data centres need generators and batteries?

An outage can take down services that thousands of people depend on. Batteries cover the first moments and generators carry the site for longer, so both must be sized for the full load.

Who connects a data centre to the grid in NSW?

The local distributor, which is Ausgrid, Endeavour Energy or Essential Energy depending on location. Large loads go through the distributor’s own large customer process, while smaller sites connect through a Level 2 ASP. See our guide to data centre power supply upgrades.

Who can increase the power supply to a server room in Sydney?

Call High Demand Electrical on 0402 559 777. We assess the load, prepare the network application and upgrade the mains and switchboard. See power supply upgrades.

Get a Power Supply Upgrade Quote: Call High Demand Electrical on 0402 559 777 for your data centre, server room or comms room. Every job needs a site assessment before scope or pricing can be confirmed.