I have written in the past about the virtues of upgrading a commercial property to LED lighting. I want to now give you a specific example of a project that demonstrates overall savings on a realistic level—let’s talk about a parking garage. The four important pieces of information that must be gathered to calculate the savings on any LED upgrade project are:
- The number of bulbs
- The number of hours that the lights are on
- The utility rate per kWh
- The wattage reduction per bulb in kilowatts
A typical 3 or 4 level parking garage uses around 250 fluorescent tube lights. The fixtures in these applications typically have two fluorescent tubes per fixture. Sometimes they have just one or even three, but commonly it’s two. This makes for a total of 125 ballasts in this project (one ballast per fixture).
Most parking garages using fluorescent tube lights operate 24 hours a day, 7 days a week. This makes for an annual usage of 8,760 hours.
We will assume a utility rate of $0.120 per kWh.
The most common fluorescent tube light operates at 32 watts. The most common LED replacement operates at 18 watts. This makes for a wattage reduction of 14 watts. We have to convert these watts to kilowatts in order to do the calculations. To do this you divide the number of watts by 1,000. So 14 watts divided by 1000 is 0.014 kilowatts.
Now we have gathered all the necessary data and we can estimate the savings of an LED upgrade in our parking garage.
We will start by calculating the estimated annual utility savings for this project.
ANNUAL UTILITY SAVINGS CALCULATION
The formula to calculate the annual utility savings is:
[Bulbs] X [Annual Hours of Operation] X [Utility Rate] X [Watt Reduction in Kilowatts]
So we plug in our numbers:
250 bulbs X 8,760 hours of operation X $0.120 per kWh X 0.014 kilowatts
When you do this multiplication you get $3,679.20. This is the annual utility savings when 250 fluorescent bulbs in a parking garage are switched out to LED bulbs.
MAINTENANCE AND EQUIPMENT SAVINGS
Calculating the maintenance savings is not difficult. We will assume the following:
1. $30 cost for a replacement fluorescent ballast.
2. $45 installation cost for the replacement fluorescent ballast. This is what an electrician usually charges to replace a ballast.
3. $2.50 cost for a replacement fluorescent bulb.
4. We’ll assume there is no cost for the installation of the replacement fluorescent bulb. It’s usually done by employees.
These are conservative estimates.
The normal life expectancy of a fluorescent bulb and ballast is about 20,000 hours. The life expectancy of an LED tube is about 50,000 hours.
So after 20,000 hours one would be making bulb and ballast changes and again after 40,000 hours. That’s two complete replacements that are avoided with LED. Let’s look at the numbers.
There are 125 ballasts. Two complete changes at $30 per ballast would be $7,500. Each ballast is installed by an electrician who charges about $45 per ballast. For 125 ballasts being changed twice the cost is $11,250.00.
And there’s the purchase of 250 bulbs at $2.50 per bulb twice. That comes to $1,250.00.
The estimated maintenance and equipment savings comes to a total of $20,000.00 over one life cycle of LED lights! And this is only for 250 lights!
The lifetime of the LED lights is just under 6 years in this case. Over the first five years the owner of this garage would save $18,396.00 on electricity and $20,000.00 on maintenance and equipment costs for a total savings of $38,396.00! Subtract from that the cost of the LED bulbs and an installation fee. You can do the installation yourself, but let’s look at what an installation for this job would typically cost.
1. 250 LED bulbs cost about $4,600.
2. Hiring an electrical contractor to install them would be about $3,850.
3. The total cost of this job is about $8,428.
4. Plus you can finance this deal for about $200 per month!
You do the math!