Hong Life CalculatorsUnderstanding the fridge energy cost and upgrade payback calculator — concept and principle
A refrigerator runs all day, every day, so its yearly energy use matters more than its wattage. This calculator compares an old fridge with a new one using their yearly kWh, works out the yearly saving at your electricity price, and estimates the simple payback period: how many years of savings it takes to cover the price of the new fridge.
How it is calculated
- Old fridge cost per year = old kWh per year × price per kWh
- Yearly saving = (old kWh per year − new kWh per year) × price per kWh
- Payback (years) = new fridge price ÷ yearly saving
For the new fridge, use the kWh per year printed on its energy label. For the old one, the original label figure is a start, but ageing seals and compressors often raise consumption; measuring with a plug-in energy meter for at least a day and scaling to a year gives a better number.
The principle
A fridge does not draw constant power: its compressor switches on and off to hold the set temperature, so the useful figure is total energy over a year. Energy labels report this from a standard laboratory test under fixed conditions, which makes models comparable even if your own use differs. Saving per year is simply the energy difference times your price. Payback divides an up-front cost by a steady annual saving, assuming the electricity price stays the same and ignoring interest, maintenance and resale value.
Worked example
- Inputs: old fridge 450 kWh/year, new fridge 200 kWh/year, $0.25 per kWh, new fridge price $800.
- Old fridge cost: 450 × $0.25 = $112.50 per year.
- Energy saved: 450 − 200 = 250 kWh per year.
- Yearly saving: 250 × $0.25 = $62.50.
- Payback: $800 ÷ $62.50 = 12.8 years.
| Old fridge kWh/year | Yearly saving |
|---|---|
| 112 | -$21.88 |
| 225 | $6.25 |
| 338 | $34.38 |
| 450 | $62.50 |
| 562 | $90.63 |
| 675 | $118.75 |
| 900 | $175.00 |
How to read the result
Compare the payback period with how long the new fridge is likely to last. If payback is longer than the expected life, the upgrade does not pay for itself on energy alone, though it can still make sense if the old fridge is failing or you need a different size. A short payback, say a few years, means replacement is clearly worthwhile. Rising electricity prices shorten payback; buying a new fridge anyway and picking the efficient model means only the price difference between models should be divided by the saving.
Common mistakes
- Dividing the full price by the saving when you would buy a new fridge anyway.
- Using an old label figure that understates an ageing fridge's real use.
- Keeping the old fridge running as a second fridge, which cancels the saving.
Frequently asked questions
How do I measure my old fridge's consumption?
Plug it into an energy meter for 24 hours or longer and multiply the daily kWh by 365.
Why does my fridge use more in summer?
A warmer room means more heat leaks in, so the compressor runs longer.
Is a fridge in a cold garage cheaper to run?
It may use less, but many fridges are not designed for very cold rooms. Check the climate class in the manual.
Sources: Regulation (EU) 2019/2016 — energy labelling of refrigerating appliances · U.S. ENERGY STAR — refrigerators