How the sum works
We take the watts saved, multiply by hours per day and days per year, then divide by 1,000 to get units. Months are counted as 30 days. Your yearly saving is those units times your rate.
The default numbers are examples. Fan power changes with speed, so check the listing for your fan.
Things this leaves out
- Running fans on lower speeds uses less power and lengthens the payback.
- A higher tariff shortens the payback.
- Replacing a fan that already needs changing is different: only the extra price counts.
Next: read Top 5 BLDC fans in India: how to choose.