Exhaust fan: units per month in Pakistan
Short answer. An exhaust fan draws around 45 watts and is typically used for a couple of hours a day, which works out at roughly 2.7 units a month for a kitchen fan. It is one of the smallest loads in the house and one of the few that reduces other loads by removing heat and humidity.
Power draw
- Low: 25 W
- Typical: 45 W — the figure used in every calculation below
- High: 90 W
Small bathroom units at the bottom, large kitchen and industrial-style wall fans at the top.
Units and cost by usage pattern
Each row is 45 W × the hours shown ÷ 1,000, over 30 days. The three cost columns exist because the rupee cost of a unit depends entirely on which slab your month lands in — the same consumption costs a light user and a heavy summer household very different amounts. Rates are illustrative and not a substitute for the tariff table printed on your own bill.
| Usage pattern | Units / day | Units / month | At Rs 12.5/unit | At Rs 27.5/unit | At Rs 36/unit |
|---|---|---|---|---|---|
| Kitchen during cooking (2 hours) | 0.09 | 2.7 | Rs 34 | Rs 74 | Rs 97 |
| Bathroom, intermittent (1 hour) | 0.05 | 1.4 | Rs 18 | Rs 39 | Rs 50 |
| Continuous ventilation in a workshop (10 hours) | 0.45 | 13.5 | Rs 169 | Rs 371 | Rs 486 |
Rate bands: Rs 12.5 — light user, protected (≈150 units/month); Rs 27.5 — average household (≈250 units/month); Rs 36 — heavy summer month (700+ units). This appliance runs all year, so the monthly figure applies in every cycle.
The load it removes is bigger than the load it adds
Cooking puts several kilowatts of heat and a great deal of moisture into a house. An exhaust fan running during and just after cooking removes both, and in a house with air conditioning that reduces the compressor work needed afterwards.
Forty-five watts to avoid several hundred watts of extra cooling is an unambiguously good trade in summer.
Running it in winter is the wrong instinct
In winter the same fan pulls heated air out of the house. Use it during cooking and switch it off afterwards, rather than leaving it running as a habit carried over from summer.
How to use less
- Run it during cooking and for ten minutes after, not all day.
- Fit a backdraft shutter — an open exhaust duct lets hot outside air in whenever the fan is off.
- Clean the blades and grille; grease build-up in a kitchen fan halves its airflow within a season.
Frequently asked questions
Does an exhaust fan reduce my air conditioning bill?
In a kitchen, yes — removing cooking heat and moisture before it spreads reduces the cooling load elsewhere. Running one continuously in an air-conditioned room does the opposite, because it pulls conditioned air out and hot air in.
Compare with
- Ceiling fan — 65 W typical
- Air cooler (evaporative) — 190 W typical
- Air conditioner (1.5 ton, non-inverter) — 1800 W typical
Filed under cooling in the full appliance index. Add your own hours in the consumption calculator, or open your actual bill with the reference number lookup.