How much can you really save by turning off the lights in the rooms you leave?

We are officially entering a period of collective belt-tightening as the economy goes through a difficult period. Everything suddenly seems more expensive, wages don't go up, and old-school money-saving methods resurface from the depths of our memory. But what if you still want to save a few more dollars? One of the classic saving tips is to turn off the lights you don't use, shares Lifehacker

On the one hand, it seems obvious: you pay for electricity. So turning things off when you're not using them makes sense. On the other hand, constantly turning off the light can be inconvenient. And the reason we switched to these fancy new light bulbs is because they are supposed to be more energy efficient. Will walking through a dark, 19th-century house save you enough money to make it worth it?

The answer is… complex. Let's look at how much money you can save by turning off the lights.

You need to count a little

So we'll have to cut some numbers the old fashioned way. First you need to know the wattage of your light bulb and the price you pay for electricity. The first is indicated on the light bulb itself or on the packaging. You must then convert those watts to kilowatt hours (kWh). For example, if your bulb is 13 watts, you multiply the wattage (13) by the number of hours it's been on, then divide by 1000. So, if your bulb has been on for one hour, your equation would look like this: way:

(13 * 1) / 1000 = 0,013 kWh

Now look at your electricity bill and find out how much you are paying for each kilowatt hour of electricity you consume. Multiply your tariff by the kWh you just calculated. Let's say you pay 10 cents for a kilowatt-hour of electricity. Turning on this bulb for one hour will cost you 0,0013 cents. If you pay 20 cents per kWh, you pay 0,0026 cents.

It's not that much. In case you're wondering, at 10 cents per kilowatt hour, leaving this bulb on for 24 hours straight will only cost you 3 cents. Obviously, less efficient lamps will cost more. For example, an old 100-watt incandescent light bulb will cost you cents if you leave it on for 24 hours straight.

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It's still not exactly a fortune, but let's look at your situation as a whole. How many light bulbs do you leave on each day and for how long? Let's say you have 10 lights in your house that you usually just leave on for eight hours when it's dark outside. Let's also say that half is nine watts and half is 13 watts, and you pay 10 cents per kilowatt hour.

(13 * 8) / 1000 = 0,104 kWh which is $0,0104 per day x 5 = $0,052

(9 * 8) / 1000 = 0,072 kWh which is $0,0072 per day x 5 = $0,036

So you spend about 9 cents a day on lighting your home. Now, assuming you do this 50 weeks a year (we'll ignore things like daylight saving time), you're spending about $31 to run these lamps a year. Should I run around and turn them off?

While it's true that running LED bulbs all the time will shorten their lifespan, they still usually last for years, even with constant use. Your cost to replace these bulbs will be fairly minimal, especially since you can buy LED bulbs for a little over a dollar each.

Other considerations for your lighting costs

Here are a few other things to consider when saving energy and money with light bulb controls:

CFL: While the math is the same for compact fluorescent lamps (CFLs), their different design means they react differently when turned on and off. Frequent switching on and off of a CFL incandescent lamp can significantly shorten its life. The rule of thumb is 15 minutes. If you need the light again after 15 minutes or less, just leave it on. If you're going to leave it off for longer than 15 minutes, turn it off.

Incandescent Bulbs: This shows you how smart it is to switch from classic incandescent bulbs, as even the lowest wattage you typically find around the house, 40 watts, will set you back about $112 a year if you use 10 of them eight hours a day. day.

Bottom line: You can save some money by turning off the lights, but not much. Whether it's worth it depends entirely on how much you value each dollar.