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What’s the Difference Between kWh and kW?

A kilowatt-hour (kWh) and a kilowatt (kW) may sound like the same thing, but they’re not quite tomato-tomahto. While both are interrelated units of measurement, the important difference between kWh and kW is that a kWh reflects the total amount of electricity used, whereas a kW reflects the rate of electricity usage.

And technically the difference between kW vs kWh is that a kWh is a measurement of energy, whereas a kW is a measurement of power, but the terms power and energy are often mistakenly used interchangeably. In actuality, energy refers to the ability to do work, whereas power refers to the rate of energy production or consumption. To really understand kWh vs. kW, though, you also need to think about time.

Timing Is Everything

An appliance consuming electricity at a rate of 2 kW vs 1 kW, for example, is consuming electricity twice as fast. In order to quantify the actual amount of electricity consumed, though, there needs to be a period of time in which that rate occurs, and that’s where a kWh comes in. 1 kWh equals one hour of electricity usage at a rate of 1 kW, and thus the 2 kW appliance would consume 2 kWh in one hour, or 1 kWh in half an hour. The equation is simply kW x time = kWh.

The Significance of kWh vs. kW

So, what does the difference between a kWh vs. kW really matter for businesses? While it may just seem like a scientific differentiation, paying attention to these measurements can lower your energy bills.

Most electric utilities bill customers for total kWh energy consumption and peak kW power consumption.  Knowing when, and at what rate energy is consumed, allows customers to reduce electricity expenses.

The average Connecticut electricity rate for commercial customers is 12.22 cents/kWh and $15.45/kW during peak hours.  For example, a 2 kW appliance that ran for 100 hours in a month would equate to 200 kWh and therefore cost $24.44 in kWh consumption charges and $30.90 in kW demand charges. That’s why it can be beneficial to use devices that consume electricity at a lower rate. If that appliance ran at a more efficient 1-kW rate, the total energy cost would be cut in half, assuming it ran for the same amount of time.

Keep in mind, however, that a lower kW device is not always able to function the same as a higher kW one. It would have to run for longer periods of time in order to generate the same amount of energy, and as a result, the device could end up running during high-cost periods.

Certain devices, however, such as LED light bulbs, can run at a lower wattage for the same amount of time as a higher wattage device like an incandescent bulb, because an LED light bulb does not let as much energy escape as heat and therefore requires less energy to have the same lighting capabilities.

That’s why it’s important to not only understand the difference between kWh and kW, but also to have tools such as energy analytics software (EAS) that can help you monitor these measurements and get insights into determining the right balance between wattage and time to ultimately lower costs.

Request a complimentary energy efficiency assessment to find out how Artis Energy’s RTIS® energy analytics platform can provide you with the visibility and insight to transform energy from a fixed cost into a distinct competitive advantage.