To function, electronic devices consume different amounts of energy.
The consumption of each depends on its power — usually indicated on the packaging and product manual — and the usage time.
The calculation is done by multiplying these two values.
For example, considering an electric shower with a power of 5,500 W and a 12-minute shower, the first step to calculate energy consumption is to convert the power to kW by dividing it by a thousand, and the time to hours by dividing it by 60.
Therefore, we have:
Pot = 5,500W/1000 = 5.5kW
Δt = 12min/60 = 0.2h
With the power in kW and the time in hours, we will have the result in kWh, a measure conventionally used to present energy consumption on our electricity bill.
Now just apply the formula:
Eel = Pot . Δt
Eel = 5.5kW . 0.2h
Eel = 1.1 kWh
If we know the cost per kWh, it is possible to calculate the cost of the shower.
The Aneel (National Electric Energy Agency) website provides the cost for each location.
If we check São Paulo, for example, where the charged rate is R$ 0.28, we will have the following result:
C = 1.1kWh . 0.28 = 0.308
The cost of a shower is, therefore, 30 cents.
This means that, in a house with a daily 12-minute shower, the monthly expense will be approximately R$ 9.00.
This calculation can be done for all electrical equipment, and it is an efficient tool to have control and an estimate of electricity expenses in any environment, whether residential or commercial.
