How much does an Irish SME office spend on energy per year?

A typical small-to-medium Irish office (300–600m²) spends €12,000–€18,000 per year on energy. Heating accounts for 35–45% of this, lighting 20–30%, and equipment (computers, servers, kitchen) 25–35%. Offices in older buildings or with poor insulation can spend significantly more.

What is the biggest source of energy waste in an office?

Heating outside of occupied hours is consistently the single biggest source of waste. Many offices heat from early morning through to evening, including lunch hours when the office may be partially empty, and some heat over weekends due to poorly configured timers. Equipment standby is the second biggest waste — computers, monitors, and kitchen appliances drawing power overnight and at weekends.

How can I reduce heating costs in my office?

The most effective measures are: proper time scheduling (heat only during occupied hours with optimal pre-heat timing), zone control (don't heat empty rooms or corridors to the same temperature as offices), weather compensation (automatically adjust heating based on outside temperature), and setback temperatures (reduce to 15°C overnight instead of maintaining 21°C). These controls can reduce heating costs by 20–35% without any change to the heating plant itself.

How much does office equipment standby cost?

A typical small office with 15–20 workstations, a server, printers, a kitchen, and miscellaneous equipment can have a standby load of 2–4 kW. At current electricity rates, that's €2,000–€4,000 per year — for equipment doing nothing useful. Simple measures like timer switches, power management policies, and smart power strips can reduce this by 60–80%.

Are there grants for office energy efficiency?

Yes. SEAI's Business Energy Upgrades Scheme covers lighting, heating controls, insulation, and building management systems with grants of 30–50%. The Accelerated Capital Allowance provides 100% year-one tax write-off for qualifying equipment. See our SEAI business grants guide for full details and application guidance.

Office Energy Efficiency for Irish SMEs

If you manage or own an office-based Irish SME, your energy bill is probably your third or fourth largest operating cost. And there’s a good chance 20–30% of it is pure waste.

The waste follows predictable patterns: heating an empty building at weekends, computers drawing power overnight, lights on in empty meeting rooms, and a heating system that hasn’t been adjusted since the day it was installed.

This guide breaks down where office energy costs go, identifies the most common (and most expensive) waste patterns, and shows which fixes deliver the fastest return.

This guide covers broader energy costs. For indoor air quality and ventilation topics specific to offices, see our separate workplace air quality guide.

The Quick Version

A typical Irish SME office spends €12,000–€18,000/year on energy
Heating: 35–45% — the biggest cost and the most commonly wasted
Equipment: 25–35% — standby loads are the hidden waste
Lighting: 20–30% — often still fluorescent, often on when nobody’s there
Most offices can save 20–30% with measures that pay back in 1–3 years
SEAI grants and ACA tax relief cut upfront costs significantly

Where Office Energy Goes

Heating and cooling (35–45%)

Heating is the single largest energy cost in most Irish offices. Cooling is significant in some buildings — particularly those with large south-facing glazing or high internal heat gains.

The weekend problem: Imagine a 400m² office that’s occupied Monday to Friday, 8:30am to 5:30pm. The heating system, set up by a contractor years ago, runs from 6am to 7pm Monday to Friday and 8am to 1pm on Saturdays “in case anyone comes in.”

That Saturday heating costs approximately €30–€50 per week through winter — €600–€1,000 per season. For a building nobody’s in.

Now imagine the timer hasn’t been adjusted for summer, so the heating runs April through May “because it’s still Ireland.” Another few hundred euros.

These aren’t hypothetical. They’re what we find in the majority of office energy audits.

Equipment and appliances (25–35%)

Office equipment is the cost that sneaks up on you:

Equipment	Typical Power (on)	Typical Power (standby)	Annual Standby Cost
Desktop PC	80–200W	5–15W	€15–€45 per unit
Monitor (24”)	25–60W	1–3W	€3–€9 per unit
Laser printer	300–600W	5–15W	€15–€45
Server	200–500W	Same (runs 24/7)	€500–€1,250
Kitchen (kettle, fridge, microwave)	Various	50–100W combined	€130–€260
Multifunction copier	200–400W	10–30W	€25–€75

A 20-person office with desktops, monitors, printer, server, and kitchen can have a standby load of 3–4 kW. At 28c/kWh, that’s €3,600/year running when nobody’s using it.

Lighting (20–30%)

Office lighting follows the same pattern as retail — older fluorescent fittings use 2-3x the energy of LED alternatives. But offices have an additional problem: over-lit spaces.

Building standards specify minimum lighting levels for different tasks. Many offices exceed these levels significantly — either because the original design over-specified, or because all lights are on regardless of which areas are occupied.

Common waste:

Meeting rooms lit all day for 2 hours of meetings
Corridor and circulation lighting at full power during daylight
Individual offices lit when the occupant is elsewhere
Emergency lighting using older lamp types (now available in LED)

The Most Expensive Habits

1. Heating an empty office

Cost: €1,000–€3,000/year in a typical SME office

The heating system runs on a fixed schedule set when the building was first occupied. Nobody has reviewed it since. It heats over weekends, starts too early, finishes too late, and maintains full temperature during holidays.

Fix: Optimise your heating schedule. Match it to actual occupancy. Add a 7-day programmable timer (€200–€500) or upgrade to a building management system (€3,000–€8,000) for larger offices. Add weather compensation so the system adjusts output based on outside temperature.

2. Equipment on overnight and at weekends

Cost: €2,000–€4,000/year

Computers on standby, monitors not fully off, printers and copiers in sleep mode, kitchen equipment, and phone chargers all contribute. Individually small, collectively significant.

Fix: Implement a “last out” shutdown procedure. Use smart power strips that cut power when the primary device (PC) is shut down. Set aggressive power management policies on all computers. Put non-essential equipment on timer switches.

3. Over-heating in winter

Cost: Every 1°C above 19°C adds approximately 8% to heating costs

When staff feel cold, they adjust the thermostat. The thermostat goes up to 23°C and stays there. At 23°C vs 19°C, heating costs are approximately 30% higher.

Fix: Set thermostats to 19–20°C (the recommended range for office work) and protect them from casual adjustment. Address draughts that cause localised cold spots — draught-proofing is cheaper than overheating the entire building.

4. Meeting rooms heated and lit all day

Cost: €500–€1,500/year for a typical meeting room suite

A meeting room that’s used for 2-3 hours a day but heated and lit for 12 hours a day wastes 75% of its energy budget.

Fix: Occupancy sensors for lighting (automatic off after 15 minutes of no movement). Radiator TRVs set to a lower temperature (16°C) as setback, rising when occupied. This is particularly effective in buildings with multiple meeting rooms.

Practical Measures by Payback

Measure	Annual Saving	Approximate Cost	Payback
Heating schedule optimisation	€1,000–€3,000	€0–€500	Immediate
Equipment standby reduction	€1,500–€3,000	€200–€500	1–3 months
LED lighting with sensors	€2,000–€4,000	€5,000–€12,000	18–36 months
Building management system	€3,000–€6,000	€5,000–€15,000	18–36 months
Insulation (roof + walls)	€2,000–€5,000	€10,000–€30,000	4–7 years
Heating system replacement	€3,000–€6,000	€15,000–€35,000	3–6 years

With SEAI grants (30–50% of cost) and ACA tax relief (100% year-one write-off), payback periods for the capital measures shorten by 40–55%.

The Monitoring Step

After implementing improvements, monitor your consumption to ensure savings persist. Without monitoring, 20–40% of savings typically degrade within 2 years as controls get overridden and equipment drifts.

Basic interval meter data analysis (free from your electricity supplier) shows your baseload, peak demand, and weekend consumption — the three key indicators of office energy waste.

BER and Compliance

Office buildings are subject to BER certification requirements and will be affected by EPBD minimum energy standards. Improving energy efficiency now delivers cost savings AND positions your building for regulatory compliance.

Next Steps

Walk your office after hours. What’s still on that shouldn’t be? What’s warm that shouldn’t be?
Check your heating schedule. Does it match your actual occupancy? Is it different on weekends?
Calculate your standby load. Read your meter at close of business and first thing in the morning. The difference is your overnight consumption.
Book a commercial energy audit for a comprehensive assessment with costed recommendations
Review the SEAI grants guide for funding options

Office energy waste follows predictable patterns, and the fixes are well-proven. Most offices can achieve 20–30% savings with measures that pay for themselves within two years.

Your office energy bill isn’t a fixed cost — it’s a reflection of how well your building is managed. The equipment matters, but how it’s controlled matters more. The cheapest energy improvement in any office is making sure the heating isn’t running when nobody’s there.