On March 18, 2015, I published Part 1 - LED Lighting's Impact to Our Home. I am including part of that blog here. The Energy Independence and Security Act of 2007, signed by President George Bush on December 18, 2007 was an energy policy intended to make better use of our resources and help the United States become energy independent. Part of the law sets energy efficiency standards for light bulbs; the first phase went into effect January 2012. The incandescent light bulbs were phased out January 1, 2012 for 100 watts, January 1, 2013 for 75 watts and January 1, 2014 for 60 and 40 watts. The following table shows the incandescent wattage and its equivalent lumen and LED-CFL wattages (Source: www.energystar.gov/la/products/lighting/cfls).
Incandescent Bulb
(Watts)
|
Minimum Light Output
(Lumens)
|
Common Energy Star
Qualified Bulbs (Watts)
|
25
|
250
|
4 to 9
|
40
|
450
|
9 to 13
|
60
|
800
|
13 to 15
|
75
|
1100
|
18 to 25
|
100
|
1600
|
23 to 30
|
125
|
2000
|
22 to 40
|
150
|
2600
|
40 to 50
|
Efficiency is measured by the number of lumens per watt. Brightness is measured by the number of lumens. Watts is the amount of energy that a light bulb uses.
Below is a comparison of incandescent, CFL and LED bulbs
- A standard 60 watt incandescent light bulb provides 13 to 14 lumens per watt.
- An equivalent CFL provides between 55 and 70 lumens per watt.
- An equivalent LED provides between 60 and 100 lumens per watt.
Source: www.energystar.gov/la/products/lighting/cfls
My first foray into efficient lighting was CFL. I then moved to LED bulbs after the bulb cost dropped to about $5.00 per bulb. I stuck to that price and only purchased them when there were sales or promotions on them. Xcel Energy and Cree offered several sales in 2014, 2015 and this year. I purchased 20 LED bulbs in August 2014. Being an energy analyst, I set up a spreadsheet to measure the electricity use of my house over the past 17 months and included Xcel’s electricity usage by my neighbors and my most energy efficient neighbors.
I now have about four years of data, with August 2014, the beginning date of LED use. As you can see from the below chart, the monthly use of electricity for a 4-person household (two teenaged boys, who think electricity is free as testified by rooms lit up to the max while empty). The use of LED clearly provided us with a savings of electricity of step-wise proportions. I then went for round two of LED bulb purchases, employing them outside which are left on for 6-8 hours depending upon the season. They provided and other step-wise decrease. I went for a third round which was to place LED bulbs in the remaining lights in the house. I also purchased smart plugs which would turn off electrical appliances, when not in use or when no one with a smart phone was present (these smart plugs turn devices on and off depending upon the presence of the smart phone, due to Bluetooth technology). Now look at the energy consumption for 2016. I have been able to take out almost 400 kilowatt-hours of consumptions, about 30% of the 2013 consumption.
So, while the above is actual savings, my spreadsheet is empirical savings based on a huge study entitled "Residential Lighting End-Use Consumption Study: Estimation Framework and Initial Estimates" by DNC KEMA Energy and Sustainability, Pacific Northwest National Laboratory. Assumptions were made about the number of lights in an average home of about 2,400 square feet in area and the number of hours each of the lights were lit, based on metering devices recordings. I used the actual number of lights in my house and used there assumption of the number of hours the lights were lit. Because my house is 4,300 square feet, there are more lights. Some of those rooms are not occupied, so the lights are not lit, while other rooms are occupied longer than the assumptions of lights lit. So, net-net, it should be approximate.
The results of switching from incandescent lighting to LED lighting was a savings of 10,500 watt-hours per day, or 10.5 kilowatt-hours per day, or 315 kilowatt-hours per month, or 3,835 kilowatts-hour/year. Back to the about graph, the empirical calculations are roughly equal to the actual savings shown in the chart. Scientists and statisticians like this kind of back testing and verification.
So, the savings are real. Now, let us calculate something different. How many average sized coal-fire power plants do these savings represent? ( The average coal-fired power plant produces 667 megawatts.) One kwh/year equals 0.114079 watts, translates to 437 watts (3,855 kilowatt-hours per year), or 0.000437 megawatts. That is my energy consumption SAVINGS per year. How many households would that represent to eliminate one 667 megawatt coal-fired power plant? The answer is 1.526 million homes. Assuming that the Bureau of Labor Statistics has measured properly, the number of households in the US, then at 133.9 million households, the savings is 87 coal-fired power plants that could be shut down. Think about that 87 power plants. This does not include electrical consumption from industrial consumers, government consumers, or corporate consumers. My cost for my almost 30% energy savings was $650. Multiply that by the 113.9 households and that equals a cost of $7.4 billion to save 30% on your electrical bill and eliminate 87 power plants. Between 2012 and 2016, there were 175 coal-fired power plants closed representing 27 gigawatts of capacity. LED bulbs barely make any of that impact (total number of coal-fired power plants generating electricity at the end of 2012 was 1,308, obviously less the 175, or 1,133). The 87 coal-fired power plants to be shut down is another 8% of U.S. capacity. WE CAN DO THIS - GET OUT AND PURCHASE LED BULBS. THEY ARE NOW ON SALE EVERY WHERE FOR LESS THAN $5.00 PER BULB.
