Most offices burn through more power than they realise — and it’s not always from where you’d expect. While lighting and air con might seem like the obvious culprits, the real electricity guzzlers are often the devices and behaviours we’ve simply accepted as ‘part of the job’.

So, what actually uses the most electricity in an office? Let’s unpack the top offenders, backed by behavioural science, smart strategy, and a little common sense — with practical takeaways for large businesses ready to rein in their energy bills.

What appliances use the most electricity in a modern office?

Here’s the short answer: Heating, ventilation and air conditioning (HVAC) systems dominate electricity use in most office buildings — typically making up 40–50% of total energy consumption. But they’re not alone at the top of the leaderboard.

Here’s a breakdown of the usual suspects:

• HVAC (Heating, ventilation, air conditioning) – 40–50%

• Office lighting – 15–25%

• Computers, monitors & peripherals – 10–15%

• Servers & networking gear – 10–12%

• Kitchen appliances – 5–8%

• Printers & copiers – 2–5%

• Standby power (phantom load) – 1–3%

But data alone isn’t enough. The key to fixing waste lies in how we think and behave in those office spaces.

Why is HVAC such a massive energy drain?

Most Aussie office buildings run central HVAC systems that are:

• Oversized for their space

• Left running after hours

• Set to rigid temperature targets (often due to outdated “comfort” assumptions)

We also see thermostat wars — some people cranking the heat, others opening windows — which creates an energy tug-of-war.

💡 Behavioural trigger: This is a classic choice architecture problem. When defaults (like 21°C settings) aren’t questioned, nobody touches them — even if they’re wrong for the space or the season.

Real-world example

A Melbourne consultancy firm found their HVAC was running 24/7 for a 9-to-5 team. A simple occupancy sensor retrofit saved them $13,000 per year. No tech overhaul — just behaviour-led thinking.

Does office lighting still matter with modern LEDs?

Yes — but in a different way.

While LEDs are far more efficient than old fluorescents, bad habits cancel out the gains:

• Lights left on overnight or in unused meeting rooms

• Daylight being blocked by blinds and screens

• Inflexible lighting zones (e.g., one switch controls an entire floor)

🧠 Bias in play: Default bias — If the light’s already on when you walk in, you’re less likely to turn it off when you leave.

A 2021 study across NSW office buildings showed that manual lighting zones led to 19% more energy use than motion-activated or timer-based alternatives.

Are computers and monitors really energy hogs?

Individually, no. But collectively? Absolutely.

A single desktop PC and monitor running all day can draw around 200–300 watts — small beer on its own. But 100 of them left on overnight for a year? You’re looking at over $10,000 in wasted electricity.

What’s worse is standby mode — aka phantom power. Devices that aren’t ‘off’, just ‘sleeping’, still sip energy 24/7.

📉 Persuasion play: Use consistency bias by setting a company-wide shutdown policy — and make the behaviour public. People are more likely to stick to actions they’ve committed to (especially if others can see it).

What about the office kitchen?

Microwaves and kettles only use power briefly — but fridges, dishwashers, and coffee machines? They’re on all day, every day.

Some common inefficiencies:

• Old fridges without energy ratings — can cost 2–3× more to run

• Multiple fridges for a small team

• Instant boiling water taps left running 24/7

A Sydney-based co-working hub slashed their kitchen energy costs by 36% by switching to smart plug timers and energy-rated appliances.

Is it worth worrying about servers and IT rooms?

If you’re housing your own servers or networking gear onsite, absolutely. These setups:

• Run non-stop

• Generate heat, adding load to your HVAC

• Often run older, less efficient equipment

Even small server rooms can quietly rack up $5,000–$15,000 in annual electricity. Colocation or cloud solutions aren’t just about security — they can be energy wins too.

💡 Framing effect: Reframing this cost from “IT infrastructure” to “avoidable overhead” can shift decision-making — especially for CFOs.

So how do you automate energy savings in an office?

This is where behavioural science meets smart tech. Automation isn’t about gadgets — it’s about removing human error from the energy equation.

Start with these:

• Occupancy sensors – for HVAC, lights, and even plug loads

• Smart plugs – schedule off-hours shutdowns for appliances

• Zoned lighting & HVAC – avoid heating/cooling empty areas

• Usage dashboards – visible data nudges better behaviour

🎯 Cialdini principle: Social proof – Showing teams live energy usage comparisons (by floor, department, or building) taps into our competitive instincts and drives down waste.

What are the hidden costs of energy waste in offices?

Beyond the electricity bill, there’s a knock-on effect:

• Premature equipment failure (from constant use)

• Over-servicing HVAC (due to 24/7 demand)

• Employee discomfort (think overcooled meeting rooms)

• Sustainability goals being missed (impacting brand trust)

For large businesses especially, these issues accumulate fast — and often silently.

How do behavioural tweaks drive real savings?

It’s not always about upgrading to the latest smart system. Sometimes, it’s about:

• Changing defaults – like adjusting the central thermostat by 1°C

• Making energy data visible – screens in common areas work wonders

• Public commitment – “Team A reduced usage by 12%” becomes contagious

• Ease of action – make shutdown the default, not the exception

🔁 Nudge tactic: Use “active choice” framing — instead of assuming employees will shut down their devices, prompt them clearly at 4:45pm: “Will you shut down your station before you leave?”

FAQ

What’s the most energy-hungry thing in an office?

Heating and cooling systems — especially in open-plan offices — typically use the most electricity.

How can I cut energy use without big investments?

Start with automation tools like timers and sensors, and behaviour nudges like shutdown policies.

Are laptops more efficient than desktops?

Yes — generally using 50–80% less power. For companies going hybrid, laptops are the smarter move.

Final thoughts

Most office energy waste doesn’t come from lack of knowledge — it comes from unchecked habits and invisible defaults. We assume the lights, air con, and screens must be on all the time… because they always have been. But change doesn’t have to be disruptive.

If you’re managing a large business, it’s worth exploring how to automate energy savings for large businesses through smart defaults, behavioural nudges, and a few well-placed sensors.

The truth is, energy savings aren’t just about cost-cutting — they’re about creating a smarter, more adaptable workplace. And in a climate-conscious world, that’s a power move.