Specific Energy Consumption

  • Energy calculation is straightforward. The unit of electrical energy is the kilowatt-hour (kWh), found by multiplying the power use (in kilowatts, kW) by the number of hours during which the power is consumed. Multiply that value by the cost per kWh, which gives the total energy cost.

        Total energy cost = (Power in watts/1000) × hours operating × cost per kWh

  • While the energy calculation is straightforward, there are variables to consider.

         -Varying electric rates

        -Differences between labeled and actual power

        -How many hours a day the device operates

        -Different operating modes 


*Varying Rates

In most communities, energy costs are not constant. Residential rates are often "layered." The more you use, the more you pay. Some utilities even charge by time of day, with lower rates during off-peak hours.


*Power Consumption

Next, we need to find out how much power the device uses. power could be calculated using power meter else the best way is to use some math:
Power (watts, W) = Current (amperes, A) × Voltage (volts, V).


*Hours of Operation and Modes

Some devices operate at full load 24 hours a day. Many devices use power even when they are "off." Chargers that remain plugged in while the devices that they charge are unplugged, can still consume power, especially in older designs.

(p.s: careful, do not forget to pull off the charger or at least off the switch when not in use)


example:

Specific energy consumption -->
In a classroom-

Tube light- 60 Watts - 5x6 = 300 Watts

Fan- 80 Watts - 4x80 = 320 Watts

Cameras- 1 Watts - 2x1 = 2 Watts

Projector- 20 Watts - 20x1 = 20 Watts

Charger- 5 Watts - 5x6 = 30 Watts

                                          -----------------

                                              672 Watts

For one month: 672x30 = 20.16 Kw

Total units: 20.16x24 = 482.84 Kwh

Total Electric bill: 483.84x5 =  2419.2/-

Commercial: 3386.80/-




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