Why turn off lights?

[Mcgiiver]

We have a fairly well insulated home. We heat with hot air, gas fired furnaces. I am wondering if it really saves money by shutting off lights in rooms not constantly used in winter. My thinking is that since they are incandescant lights, in winter leaving them on, produces heat, which helps lessen the heat needed to be produced by the furnaces. Summer is obviously a different matter. Since energy is not lost, just changed in form, I am thinking the lights on approach is not very bad. I will acknowledge that the furnace is probably a more efficient way to produce heat, but we need light anyway. Any thoughts?

[Cobb]

Being a reverse vampire I leave lights on. I found the cf buls work best, about a year on 24x7, then they burn out one dark night. The filiment bulbs ask about 39 days, then go poof. LED bulbs like to flicker when they go bad.

I had gas heat and in the winter would switch out to filiment bulbs to heat and reduce use of gas heat as it was noisy to have it on all the time. It made a good deal of heat, but it ran my power bill up 10 bucks a month with 3 of them on all the time.

[RobertISaar]

in the winter, it's really a question of how much heat you're getting for the money... in the summer and above comfortable temperatures, anything that draws power gets evil glares from me.

Watts to Btus (IT)/Hour Conversion Calculator

that should give you a rough idea of how much heat you're generating, you'll have to figure out cost on your own since power rates are so incredibly variable depending on where you're located, time of year, even time of day for some people.

in my personal digging:

1500 watt electric heater = 5118 BTU/hr assuming it's running at 100% DC. BTW: electric heat is so close to 100% efficient, it's hilarious when ads run for those infrared heaters that claim to be better than a regular electric heater.

http://www.handymath.com/cgi-bin/electric.cgi

it costs me 11.6993 cents per KW/H last month for power.

if it ran at all times(24 hours X 30 days = 720 hours), it would end up costing 126.35 for 3,684,960 BTUs.

compare that to how much it costs you to run the gas furnace and you'll see if you're actually saving or losing money.

[roosterk0031]

I have propane heat, one gallon of propane cost $1.50 and has 92,000 btu, furnace is just better than 90% efficent so I get about 83,000 btu of heat for $1.50, at 12(using the above cost, mine's closer to 15) cents a KWH, $1.50 buys 12.5 kwhs or (1 kwh = 3412 btu) or 42650 btu, about half the heat from electricity as from propane. Electric heat would cost me 2x as much per month.


Natural gas is way better, it's usually sold by the therm I think, which is 1,000,000 btus, last time I look it was about $4-5 a therm. one therm = 293 kwh which would cost $35 in electricity. Electric heat would cost 7-8x as much per month. (I don't and have never had natural gas so not sure on these numbers)

EDIT: forgot to factor in 90% efficient furnace with Natural Gas so closer to 1/6-1/7the cost of resistant electric heating.

[redpoint5]

In the Northwest, heating with gas is roughly 1/3 the cost of heating with electricity. I would bet just about anywhere in the country gas is 1/2 the cost or better.

Lights that tend to be used for extended periods of time are either CFL or LED. Lights that get cycled often such as closets and vanity are all incandescent. My outdoor lights are on a switch that knows when sunrise and sunset is, and acts accordingly.

[S-cort]

There are many reasons to turn off the lights. I am an energy auditor by trade. As Roosterk0031 states above you will pay roughly 6-7 times as much to heat your home with electricity than with natural gas. There are many factors that can make it complicated: furnace efficiency 80-96%, incandescent bulb heating efficiency 95%, and transmission losses of 35% on average from the power plant to your home. The take away is that unless you are getting electricity for under 2 cents per kwh you will pay more.
Beyond saving you money, anytime you conserve electricity you are reducing emissions at the power plant. This is especially important if your powerplant burns coal. Coal is a dirty dirty fuel that emits greenhouse gases that are causing climate change.
You are best off using the gas furnace and supplementing with electric space heaters as little as possible. Change those incandescents out to LEDs or CFLs and see even more savings.

[WyrTwister]

I once lived in an efficiency apartment that had a window unit . Refrigeration cool / resistance heat . With incandescent lamps , in cold weather , I turned on every light in the place . This gave a well distributed heat . I only turned on the resistance heat when it got really cold .

Since I was heating with electricity , it made little difference between the two methods . And with the incandescent lighting , I got plenty of light , also .

God bless
Wyr

[redpoint5]

Originally Posted by WyrTwister

I once lived in an efficiency apartment that had a window unit . Refrigeration cool / resistance heat . With incandescent lamps , in cold weather , I turned on every light in the place . This gave a well distributed heat . I only turned on the resistance heat when it got really cold .

Since I was heating with electricity , it made little difference between the two methods . And with the incandescent lighting , I got plenty of light , also .

God bless
Wyr

For your situation, it seems that leaving lights on is nearly equivalent in efficiency compared with the resistance heater. If you prefer the extra light, then that is an excellent way to heat.

During summer months though, I would swap out the incandescents with CFL for the lights that tend to stay on long periods of time.

[WyrTwister]

Originally Posted by redpoint5

For your situation, it seems that leaving lights on is nearly equivalent in efficiency compared with the resistance heater. If you prefer the extra light, then that is an excellent way to heat.

During summer months though, I would swap out the incandescents with CFL for the lights that tend to stay on long periods of time.

Weren't no CFL's . :-) This was back in the stone age , in my early / mid 20's .

I did skimp on the lighting in the summer .

Also , the apartment was on the 2nd of 3 floors . So the apartment had a conditioned space above me and below me . And only 2 outside walls . The side walls were common with conditioned space , also .

The disadvantage with the 2nd floor was toting my stuff up or down the stairs , when I moved in and moved out .

I now have CFL's all over the house . Been using them a LONG time . Since before they came down in price .

But , I have gas heat . Except for the 12,000 BTU mini split A/C - Heat Pump we installed this summer . I have been experimenting with the HP ( living room and dining room ) . So far , I think I like it .

God bless
Wyr

[gone-ot]

Aah, but the REAL question is: which co$t$ more, electricity for the lighting or electricity/gas/oil for heating?

If electricity is less costly (as I think it is), then lights can be beneficial for reducing heat loss, but certainly NOT useful for creating enough heat to offset outside cold.

Here, in ariz-zona, where summer A/C isn't cheap, I religously turn OFF anything that's not absolutely needed...or actually IN USE.

...and, I've found that LED lamps are slightly more efficient (9W vs. 14W for 800-Lumen, 5K lamps) than CFL's at power consumption, but vastly better at survivability when installed pointing downward. CFL's tend to "cook" their electronics when oriented base-UP/globe-DOWN...causing their electronics to "cook" and fail WAY too often. Hence, we've switched to LED's.