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Turn off the Lights

In this episode (172) – Turn off the Lights . . .

It happened on Thursday; Fall officially arrived, and soon darkness will be upon us by 5:00 p.m. To prepare, let's look at our energy usage and the most cost-effective way to light our home this winter. Compulsively turning off household lights to save money is a habit most of us have, but it's not the money-saving power move we think it is - unless . . . 

Back in my day, it made sense to turn the lights off when you left the room. As Mom always said, "Turn off the lights! We're not made of money."

Let's be clear, if you turn off any device in your home that uses electricity, no matter how big or small the device, you will, of course, save money. It doesn't matter if the device is a power-hungry tungsten lamp or a tiny night light in the bathroom. You are obviously not paying for electricity if it isn't using electricity.

However, LEDs completely changed the game regarding serious energy savings. The efficiency of LED lighting compared to traditional incandescent lighting is mind-blowing. LED lights use a fraction of conventional incandescent bulbs' energy. Such a small fraction that—depending on the bulbs in question—you can power anywhere from six to a dozen LED bulbs with the power required by the one incandescent bulb you're replacing.

It helps to look at some numbers to put things in perspective. For example, let's say that there are ten light bulbs in your home that you keep on. And let's say you leave them on for five (5) hours every night. These are ten 60-watt (w) incandescent bulbs. They consume a total of 600w per hour or 0.6 kWh. Multiply that usage by the cost your local utility charges per kWh; the U.S. national residential average is ~$0.12 per kWh, so we'll use that. (Note; California average is ~$0.25 per kWh).

Each evening when you leave those ten bulbs on after work, it costs you $0.36 [($0.12 x 0.6) x 5]. Per month, that's * $10.96; per year, it's $131.49. Now let's say you have ten 60w-equivalent LED bulbs used under the same conditions—5 hours per day in the evening after work. Most 60w-equivalent bulbs use 8-9 watts of energy, so we will use 8.5w for our calculations.

Now your per-hour energy use isn't 600w; it's 85w. At the U.S. national average ($0.12), running those ten bulbs for 5 hours after work costs you $0.03 per day [($0.12 x 0.051) x 5], that's $0.91 per month and only $10.96 per year.

To get close to the energy expense of leaving the ten incandescent bulbs on in the evening, you'd need to leave on roughly 70 equivalent LED bulbs.

The point of this exercise isn't to encourage you to be wasteful for the sake of being extravagant. But with the efficiency of LED bulbs, flipping lights off in a room you'll be returning to shortly or not leaving accent lights on around your house just doesn't make a lot of sense.

The cost to run one 60w-equivalent LED bulb is ~$0.001 —a tenth of a cent per hour. You're talking 1,000 hours of operation to hit one dollar at that price point. And hey, if you want to save more money (power), unplug your lesser-used electronics or put them on a power strip; so you can flip them off when you're not using them.

For example, a TV uses about 18W of idle power. That's two LED bulbs worth of energy, 24/7 ($18.93/yr.), completely wasted because it's just powering a TV that's not even turned on.

And granted, you probably leave frequently used items and crucial things like your internet modem and router plugged in; you'll save way more power per year by unplugging unused electronics than you will by beating yourself up for leaving the kitchen lights on.

With winter approaching, if you haven't made the switch to LED lights - think about it.

I'm Patrick Ball; thanks for listening. I'll see you in the next episode.

* (Calculations assume 30.44 days/month & 365.25 days/year) 


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