Hello Neighbor
You don't know me. I live in this subdivision a few blocks north of you on a different street. I drive by your house on my way to and from work. For much of this year, I notice the five incandescent lights in your garage are turned ON. It doesn't seem to matter what time of day. They are visible through the windows in your garage door. Your lights are often ON when your door is open in broad daylight.
I am concerned about the environment and the waste of natural resources. I taught science to high school students for 38 years and stressed to them the importance of conservation. Seeing your lights ON unnecessarily so much of the time brings about two questions. First, what is the cost in dollars, and the cost to the environment? Second, what can be done to reduce those costs? Yes. I am going to tell you answers to both.
What is the Cost?
I need to make a couple of assumptions based on what I see when I drive by. It appears you have five bulbs of at least 100 W each. It appears your lights are on as much as 10 hours each day. You can adjust the figures below if those are wrong. Whatever the case, you will get my point.
First the $$$...
5 x 100 W = 500 W = 0.500 kW of power
10 h/day x 30 day/mo x 12mo/yr = 3600 hours per year of time
Energy = power x time = 0.500 kW x 3600 h = 1800 kWh of electric energy
1800 kWh x $0.10 per kWh = $180 each year based on our utility bill figures
Now the resource...
Typical thermal efficiency for electrical generators in the industry is around 33% for coal and oil-fired plants. That means you are receiving only one third of the burned coal's heat energy from the power plant near us. The plant thermal losses go to the environment.
1800 kWh x 3,600,000 Joules/kW = 6,480,000,000 Joules to light your bulbs
A Joule is about the energy needed to lift an apple from the floor to the counter.
6,480,000,000 Joules = 0.33 x power plant energy
Plant burns coal to make 19,640,000,000 Joules so you get 6,480,000,000 Joules.
A kilogram of hard coal (2.2 lbs) makes 29,310,000 Joules of heat energy when burned.
19,640,000,000 Joules x 1 kg/29,310,000 Joules = 670 kg = 1480 lb of coal
That's about half of what the typical American car weighs. Pile that in your driveway
and burn it over the course of a year to light your bulbs. It seems unnecessary.
This figure does not include the mining and transportation costs to get the coal.
How to Reduce the Cost?
Shut OFF the lights more often.
Buy Compact Fluorescent bulbs.
Incandescent bulbs convert 25% of the electric energy into light and 75% into heat. That's why the bulbs are so hot. CFL bulbs are much more efficient. They use one quarter of the energy for the same light output. This alone would save you a lot of money.
Use CFL bulbs and turn them OFF when not needed to save even more.
Don't be offended by my note to you. Yes, I may have overstepped my boundary. But, as a concerned citizen of the Earth, I feel it is up to all of us to do our part to help save resources and keep our planet habitable. There are many simple things we can do. This is one of them. Education is the way to bring that to the attention of people such as yourself. It's easy to follow our habits and forget some simple actions that can have some big consequences. I trust you understand.
Sincerely
Your neighbor
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