Throughout my house for safety reasons I have these LED night lights that are automatically on once its dark in every hallway or room that isn’t a bedroom. These are mainly for if someone has to use the bathroom in the middle of the night or any other scenario where someone wants to walk through the house in the middle and not have to find the main switch to turn on the regular lights.
According to the spec sheet it says
0.3W LED and without bulb replacement, Less than 25 cents cost for annual power consumption.
Now since I’m only walking through my hallway in the dead of night maybe once a night, I was wondering if these nightlights were even worth it? If each hallway or room only has one or two LED 8.5 watt bulbs and I will only turn those on for less than 3 minutes a night (and usually its only a hallway then the bathroom and back) am I really saving money with these or should I just reach for the light switch instead of buying these and using them 24/7?
Your post does seem to confuse energy usage vs cost and you seem to use the term somewhat interchangeable, though each one may motivate a person differently. If its cost savings you are after, an always on night light may be more cost effective than one that turns on or off by itself.
But strictly looking at the energy usage, which one must consider the energy that goes into making the small lights, as well as the energy use fraction for the existing switch and light that will have slightly less life due to that increased run times and switch cycle. If looking at the cost one must consider the replacing of the switch, & possibly having a electrician to do it and you may be doubling the amount of switching you do on that switch.
Another factor is the question do you want a full bright light coming on in the middle of the night? Many people don’t and it can interfere with sleep patterns. For me I have 3 light switches for my bathroom, and for one I have a small compact florescent bulb in it. I use that switch for night time/ having to use the bathroom during sleeping times. The CF bulb does not reach full brightness till about a minute after I turn it on, so for quick stuff the light is very gentle and if I need more time it gradually brightens up.
The night lights use more electricity. 0.3 watts x 12 hours per day = 3.6 watt-hours. One 8.5 watt hall light (which is pretty bright for an LED) for three minutes is only 0.425 watt-hours, or about 1/8 as much. Since you say you have multiple night lights, and only one or two full-sized hall lights, the ratio tilts even more in favor of the hall lights. The $0.25/year cost is apparently assuming either fairly expensive electricity (like $0.20/kWh) or being on for much more than 12 hours per day. Most night lights seem to have pretty sensitive photocells, but there may still not be enough ambient light to turn them off even during the day. Regardless, we’re talking about $0.25/year for the night light and $0.03/year for the hall lights.
Maybe also consider replacement cost. LED night lights aren’t exactly expensive, but a 2-pack may be $5 or $6 and they don’t seem to last as long as they should. I don’t think I’ve ever had one burn out, but they never maintain their brightness for long. I think an LED is technically considered failed when it falls below 80% of its initial/rated brightness, so all of the ones I’ve ever bought have “failed” within a year or two. Your hall lights should last way longer than that, even with their non-middle-of-the-night usage. Also, what @kanicbird said about not wanting to turn on bright lights at night is important, if irrelevant from a cost standpoint. You also don’t want to turn those on if they might wake up someone else because their bedroom door is cracked open.
While we can talk about which one is more efficient, both of them are so extremely efficient that we really ought to be comparing other factors instead, like which one is less likely to result in a stubbed toe from not seeing something left in the middle of the floor.
This is small potatoes. We think about the energy wasted by such lights because, well, they are visible. But every Wall Wart adapter you have plugged into the wall can consume .5W to 2W 24/7 due to eddy currents, even if the thing they are powering isn’t on - or even plugged in to the wart. How many wall warts do you have in your place? That phone charger sitting there while your phone isn’t charging is still eating power.
Cable set top boxes are often horrible, because their ‘standby’ mode is nearly fully functional, and they can consume as much as 30W on standby. Some people have three or four of these in their homes. TV’s and monitors can consume 5W each or more in standby. Wireless routers are on all the time. Alexa and Google Home devices can consume a reasonable amount of power when not in use, because they are still listening and processing.
Poorly designed smoke alarms can consume 2W constantly. The best ones less than half a watt. If you have a cheap smoke alarm, you could check intomits power consumption and if it’s high replace it with one that isn’t, You probably won’t save the money it costs, though.
Air conditioners, heaters, and other devices with large transformers can be a real energy sink. An AC unit can consume as much as 30W when it is NOT running.
If you have a multifunction printer on your home network, it’s probably drawing some juice all the time. If you have an XBox 1 in ‘instant on’ mode, it’s drawing a continuous 13W of power. A Playstation 5 draws a coiple of watts in standby.
Your home or apartment is filled with energy-leaking devices. I wouldn’t sweat the night light, especially if it improves your quality of life. You’d get a lot more bang for your buck by simply turning off the ‘instant on’ features of your TVs and monitors and powering down your computers and accessories rather than leaving them on standby.
These “vampire devices” get a lot of talk, but really, they’re small potatoes, too. You should worry a lot more about how much energy your AC consumes when it is running.
Check that your air filters are clean (dirty air filters will result in poorer heat transfer because of deposited dirt on the heat exchanger (coils) surface), check the refrigerant levels are okay, wash the fins on the condenser.
those 3 alone will give you the biggest bang for your effort.
Usually the only transformer in an a/c system is for the 24 volt control (thermostat) side. I’m not aware of other “large transformers” in such devices. That said, the crankcase heater for the a/c compressor uses roughly 30W and that can be energized all winter when you’re not otherwise using the thing. Is that what you might be thinking of?
It really depends. Each one of those devices is trivial, but some homes have lot of them. In our bedroom we have a TV on standby, an Apple TV, two clock radios with wall warts, two iphone chargers, an elliptical with a wall wart, and a telephone with a wall wart. That could be as much as 10W being consumed 24/7.
In our kitchen we have a power bar full of chargers, a microwave oven on standby, a radio with a wall wart, a Keurig that has a ‘constant heat’ for the reservoir option, and a USB-C charger on our eating bar for my iPad.
I wouldn’t be surprised if our ‘vampire’ devices consume 50-100W total, every hour of the day. Maybe even a little more if you add in the furnace, AC residual, etc.
It’s not a huge amount, but 100W X 24 hours is 2.4 kWh,. Depending on where you live that could be as little as 18 cents per day, or as high as a dollar per day.
The AC thing is news to me. Assuming I want to have AC, is there anything to do about this? Is the heater there to keep things from freezing, and it’s only on when the weather gets cold enough?
It’s to prevent liquid refrigerant from damaging the compressor, which can happen in cold weather. I’ve heard that you can shut off the breaker for the winter, but when you turn the breaker on again you have to wait 24 hours before actually running the a/c.