What Should I Install In My Underground Parking Garage In Humid, Salty air?
I recently got an email from a gentleman in Florida who was looking to replace lighting in an underground parking garage near the ocean. He was looking to explore T8 fixtures, but was concerned about the humid, salt air as the parking garage had some open exposure to the humidity. If he went with T8, then he was thinking they would have to be explosion proof.
But, he wanted to know how LED would work in his situation. I put together an email, which is the body of this article, and sent it off to him for consideration. Shortly after I sent the email he responded back and said "Jimmy, You are great!". Never hurts to stroke the ego, but it got me thinking that maybe others had the same types of questions.
Here are his questions along with my answers.....
1) Does The LED have a more pleasing, color-friendly light?
As to the color of light from the LED, yes, they do consistently perform very well and have a very crisp look to them. I can actually get you a higher CRI with T8 bulbs that will give the same lighting effect as the higher CRI LED fixtures.
I have them in my office, they are 5900K with a CRI of 93, but they are nearly $10 each.
I always think of Parking Garages as being very dark, so the high Kelvin, high CRI values would be quite a change.
Also the higher the values, the brighter the light seems to your eyes.
Based on this picture, I don't think it would take much! YIKES!!!
2) Do LED's have a longer life?
LED do have a much longer life. The lifetime of the LED Canopy fixture I am recommending has a lifetime value of 143,000 hours. The best I have seen for fluorescent T8 is 42,000 hours.
That means you will change out the t8 bulbs over 3 times to get the comparable lifetime. That doesn’t include ballast changes you might incur along the way, which with the conditions these are in, would be a possibility.
3) How much more efficient are LED fixtures vs. T8 fluorescent?
LED is much more energy efficient. Assuming 127-277 input voltage at 8’ high ceilings, you would only be using 58 watts.
The T8’s are all over the place for rated wattage, but the best we have worked with is a 4 bulb T8 that is rated for around 78 watts. That means you will be burning nearly 20% less energy with the LED over the T8. When you consider the lifetime values, the higher upfront costs should easily outperform the T8 based on energy consumption.
4) My application is next to the ocean, will the humid, salty air cause arcing in the fixtures?
As far as arcing and humidity, if the lights are wired properly you shouldn’t have issues with
arcing, but the salt water climate you are in may impact that more than I realize. We have the freshwater up this way.
You can’t get away from the humidity, so LED would be a good option here as well. But, not all LED fixtures are rated for wet areas.
I was originally going to recommend a 36 watt Troffer, but I notice those are for dry areas. The LED canopy light I am looking at is rated for wet areas.
Wet areas are typically those areas that are exposed to direct exposure to moisture. Poor electrical work will never help the situation, and it appears as though you may have some issues there.
5) We are going to have to do some re-wiring, is it true that with the lower draw of current on LED mean fewer circuits and lower re-wiring costs?
Less wattage does indeed equate to less wiring and the ability to put more lights on a circuit. Your cost escalates quickly based on the amount of circuits you’re dealing with, because the home runs often use up the most wire.
The fewer times you make a home run, the better as your costs will be lower for labor and material.
If you did need new wiring, you could use conduit as you mentioned. Being a parking garage, I would think it would already have conduit there, but every jurisdiction is a little different.
6) Will LED qualify for a tax deduction?
There are a couple different types of incentives out there, cash incentives and tax deductions to encourage investment into energy saving technologies. You will have to check out your local utility for what types of incentives they have out there.
They will either be based on wattage/kilowatt-hour reduction, or you may have a list already that pays out a fixed dollar amount based on the fixture you are using. For tax deductions, there is the Energy and Policy Act of 2005 that was renewed in 2008 when President Obama took office. It is set to expire at the end of 2013.
So your time is a little limited in regards to that. But, if you were able to qualify, it would be good for up to a $.60 per square foot deduction. It’s not something automatic though, you have to have it certified by a qualified person. A Contractor or Engineer would be that type of person.
7-How does the LED compare in operating costs vs. t8?
The upfront cost of the LED will be higher than what a typical T8 fixture would run. To see, I have provided a comparison of T12 vs. T8 vs. LED Canopy Fixture:
Operating Cost Assumptions
We can assume the 2x4 T12 is using 178 watts approximately.
We will base it on a 12 hour day, assuming they are on at night only.
We will assume a rate of $.10 per k/hr.
You have 180 fixtures.
180 fixtures x 178 watts = 32,040 watts
32,040 watts/1000 = 32.04 kw
32.04 kw x 4,380 hours operations = 140,335 kwh
140,335 kwh x $.10 kwh = $14,033.50 to operate your 2x4-T-12 annually
Replacement T8 Fixtures
180 fixtures x 73 watts = 13,140 watts
13,140 watts/1000 = 13.14 kw
13.14 kw x 4,380 hours operations = 57,553.2 kwh
57,553.2 kwh x $.10 kwh = $5,755.32 to operate replacement 2x4-T-8
Replacement LED Fixtures
180 fixtures x 58 watts = 32,040 watts
32,040 watts/1000 = 10.44 kw
10.44 kw x 4,380 hours operations = 45,727 kwh
45,727 kwh x $.10 kwh = $4,572.00 to operate replacement LED Lighting
T8 Replacement – 36,000 hours or 8.2 years before replacement
LED Replacement – 143,000 hours or 32 years before replacement
If your incentives are based on kwh saved vs. existing T12, you will have saved;
T8- 82,802 kwh saved
LED-94,608 kwh saved
What Do You Think?
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