There’s one common thread that runs through each of these questions: the difference between watts (W), kilowatts (kW), và kilowatt-hours (kWh). Calculating watts to lớn kWh could help you understand the answers khổng lồ the questions above.Bạn sẽ xem: Watts to lớn kilowatts (kw) conversion calculator
The energy industry is almost as bad as the lighting industry at using abbreviations & jargon, so we’ll try to lớn break each of these down with some practical examples.
In this article, I’m going to use the analogy of equating electrithành phố to lớn water. This is a common analogy that we can’t clayên ổn as our own, but hopefully our specific examples will help explain how much energy lighting really uses.
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What is a watt (W)?
You’ve probably made a lot of lighting decisions based on wattage. You unscrew a burned out light bulb và look at the top và see “60W.” All you have is a light bulb labeled “25W,” so you screw it in, và to lớn your dismay, it’s way too dlặng. You go lớn the store và pick out a “60W” bulb. Your lights are bright again. Crisis averted.
So what is a watt, anyway? Technically speaking, it"s a unit of electrical power equal to 1 joule per second. Light bulbs are rated in watts to lớn indicate how much energy they consume.
Does the wattage of a light bulb have sầu anything lớn bởi with brightness? Well, sort of.
For so long, many of us have sầu associated watts with the amount of light a bulb gives off. In general, that works well with traditional incandescent light bulbs. A 60W incandescent bulb typically gives off around 650-800 lumens. A 25W incandescent bulb typically produces around 150 lumens — much less light.
With the introduction of more efficient lighting, though, it’s not uncommon lớn see a “60W equivalent” bulb that uses far less energy & gives off roughly the same amount of light. Here’s a breakdown:
|Lumens per watt (LPW)||13||18.5||60||75-100+|
(The photos above are representative sầu of the giải pháp công nghệ, not specific product specifications.)
So, as you are comparing light bulbs, remember that wattage is a measure of how much energy the light bulb will use as it produces light, & the lumens will give you a measure of how much light it will produce.
Ready khổng lồ shop light bulbs? Cliông xã here và use the filters on the left to lớn sort by lumens.
What is a kilowatt (kW)?
Just lượt thích watts, kilowatts is a measure of how much energy something will consume. Going from watts (W) khổng lồ kilowatts (kW) is a pretty straightforward calculation: 1kW is equal khổng lồ 1,000W. To convert W to kW, divide the total wattage by 1,000.
Here’s an example: if you turned on ten 100W light bulbs, that would equal 1kW of energy usage.
10 bulbs x 100W = 1,000W
1,000W / 1,000 = 1kW
It’s also worth noting that kW can be synonymous with “demand” if you’re talking to lớn a utility company. Imagine that you turn on those ten light bulbs và a 3,000-watt clothes dryer at the same time. The utility company needs to lớn be able to supply enough electriđô thị khổng lồ meet that 4kW of demand at the moment you turn everything on.
Your energy usage, though, depends on how long you keep everything on, which leads us to…
What is a kilowatt-hour (kWh)?
Let’s go back khổng lồ the example of having ten 100W light bulbs. How much energy would you use of the course of a month if you turn them on for 10 hours a day?
That’s where kWh comes inlớn play. Here’s the breakdown:
10 bulbs X 100W = 1,000W or 1kW of lighting
10 hours of daily use X 30 days in the month = 300 hours of use
1kW X 300 hours of use = 300kWh of energy consumption
So why is kWh so important if you can compare lighting products based on wattage & light output? In the kết thúc, a significant portion of your electricity bill is based on your energy consumption in kilowatt-hours. If you want lớn calculate the dollar savings you’ll get from a retrofit lớn more efficient lighting, kWh will come inlớn play.
kW vs kWh: A practical example
Okay, enough theory.
How about a practical example to explain the difference between kW và kWh? (Here’s where the water analogy comes in.)
Let’s imagine that we have two garden hoses, one with a 3/8-inch diameter and one with a 5/8-inch diameter.
The 5/8-inch hose has a larger capađô thị than the 3/8-inch hose, so it can carry more water at any given moment. This is the idea of kW — the capađô thị to lớn use electricity.
Now, let’s imagine that we want khổng lồ fill up a two-gallon watering can. The amount of water that we use lớn fill up the can is two gallons. This is the idea of kWh — the total amount of energy consumed over time.
How long would it take to lớn fill up the watering can? That depends on which hose we choose. The 5/8-inch hose — because of the larger capacity — will fill up the watering can more quickly than the 3/8-inch hose.
In the same way, a 100W light bulb will consume a total of 10kWh of energy faster than a 60W light bulb.
Here is a parallel example:
|Step 1: Capacity|
Let’s use our 5/8” diameter hose which we will assume carries 16 gallons per minute
|Let’s use a 60W (0.06kW) incandescent bulb|
|Step 2: Time||Let’s run the hose for đôi mươi minutes||Let’s operate the light bulb for 2,000 hours|
|Step 3: Consumption||16 gal/ min x 20 min= 3trăng tròn gal consumed||0.06 kW x 2,000 hrs = 1trăng tròn kWh consumed|
Let’s bring in the efficiency piece to lớn the example & compare an incandescent light bulb to lớn an LED light bulb:
|Step 1: Capacity||60W (0.06kW) incandescent bulb||5W (0.005kW)LED bulb|
|Step 2: Time||Let’s operate the light bulb for 2,000 hours||Let’s operate the light bulb for 2,000 hours.|
|Step 3: Consumption||10.06 kW x 2,000 hrs = 1đôi mươi kWh consumed||0.005 kW X 2,000 hrs =10 kWh consumed|
In this example, we got the same light output, và we operated the light bulbs for the same amount of time, but the total energy consumption over the 2,000 hours of operation was 110 kWh less for the LED bulb.
W vs kWh in lighting rebates
Lighting rebate programs are one area where we tend to see the difference between a wattage reduction & kWh usage reduction on a regular basis.
In general, there are two kinds of lighting rebates we run across:
Demand-reduction lighting rebates:
Some lighting rebates are focused on the wattage reduction of a retrofit. If you replace a 100W PAR38 bulb with a more efficient 14W LED PAR38, the utility will pay a rebate based on the 76 watts of energy reduced.
Usage-reduction lighting rebates:
Other lighting rebates are focused on the overall reduction in energy usage for a retrofit. If you operate your lighting for 4,3đôi mươi hours per year (12 hours per day, 360 days per year), the 100W PAR38 would use 432 kWh per year & the 14W LED PAR38 would use just over 60 kWh per year.
In this case, the utility would pay a rebate based on the 372 kWh of energy consumption saved over the course of the year from the more efficient lighting.
Hopefully our explanation of the difference between watts, kilowatts, & kilowatt-hours is helpful.
We want to make this as easy as possible, so we’ve sầu put together a calculator that you can use khổng lồ quickly — và easily — get the numbers you need.
Watts to kWh calculator
Now that you’re a pro at knowing the difference between kW and kWh, check out our posts on understanding the total cost of lighting or how to calculate energy savings and paybachồng for lighting projects.