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HVAC Running Cost Calculator

How much does your air conditioning actually cost to run each year? Enter your unit's cooling capacity, efficiency rating (EER), daily usage hours and electricity price to see the exact annual cost — and whether upgrading to a more efficient system would save you money.

Quick Start

Step 1. Find your unit's specs
cooling capacity (kW or BTU) and EER from the data plate or manual
Step 2. Enter usage hours
how many hours per day and days per year you run the AC
Step 3. Set electricity price
your current tariff per kWh from your energy bill
Step 4. See results
annual kWh, cost per hour, annual cost and CO₂ emissions

Tip: The EER (or SEER) is printed on the energy label on your unit, or in the product manual. If you only know BTU capacity, divide by 3.412 to get kW (e.g. 12,000 BTU = 3.5 kW).

Settings

Your AC / HVAC System

Selects a typical EER for the system type. Adjust below if you know your exact rating.
From the data plate or manual. Common sizes: 2.5, 3.5, 5.0, 7.0 kW. Divide BTU by 3.412 to get kW.
From energy label or manual. Modern inverter units: 4.0–6.0. Older units: 2.0–3.0. Portable: 1.5–2.0.
If all units are the same model and usage pattern, multiply here.
Your current electricity tariff. Check your energy bill.

Cooling Usage

Average hours the AC runs on days you use it.
Mediterranean / Southern Europe: 120–180. Northern Europe: 20–60. Middle East: 200–300.

Toggle on if your split or heat pump unit runs in heating mode during winter. We will add the heating cost to the total.

Multi-year Projection

Air conditioning running costs explained: EER, SEER and how to reduce your AC electricity bill

How to calculate air conditioning running cost

Air conditioning running cost depends on three things: how much cooling power the unit uses (cooling capacity divided by EER), how many hours it runs, and your electricity tariff. A 3.5 kW unit with EER 3.5 draws exactly 1 kW of electricity — at €0.28/kWh that is €0.28 per hour. Over a 90-day cooling season at 8 hours/day, the annual cost is €201.

EER vs SEER: which number to use

EER (Energy Efficiency Ratio) is measured at a single fixed operating point (typically 35°C outdoor temperature). SEER (Seasonal Energy Efficiency Ratio) averages efficiency across a range of temperatures representing a full cooling season — it is always higher than EER because the unit runs at part-load and milder temperatures for most of the season. For running cost calculations, EER gives a more conservative (slightly pessimistic) estimate; SEER gives a more realistic annual average.

Why portable ACs cost so much more to run

Portable air conditioners exhaust hot air through a duct — but this also creates negative pressure in the room, drawing warm air in through gaps around doors and windows. The effective cooling is significantly less than the rated capacity, while electricity use remains the same. Real-world EER for portable units is often 1.0–1.5, versus the rated 1.8. A wall-mounted split unit with EER 4.5 delivers the same cooling for one-third the electricity.

Reducing AC running costs

The most impactful changes are: raising the setpoint by 1–2°C (saves 6–12%), using ceiling fans to allow a higher perceived comfort temperature, blocking direct sunlight with external shutters or blinds (reduces cooling load by 20–30%), and running the AC during off-peak tariff hours if you have time-of-use pricing. Cleaning or replacing air filters every 3 months maintains rated efficiency — a clogged filter can reduce efficiency by 5–15%.

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