I am a big fan of LEDs. They are energy-efficient and have a long service life. They are ballast-free, which removes a potential point of failure and a consumer of energy.
However, I have not always been sold on replacing fluorescent tubes with LED tubes due to the high material cost, as much as $50 each. The incremental benefit (fewer watts consumed) was not enough to overcome the incremental cost. For clients with low operating hours and/or low energy costs (10 cents/kWh), I had been playing it safe by retrofitting T-12 systems with T-8s or T-5s. The results were very predictable.
Two factors have changed my view. One, the cost of LED lamps continues to fall. Second, a snap-in LED design simplifies installation, further reducing costs. These LED tubes look a little like light sabers from Star Wars movies because they do not have pins on their ends, unlike fluorescent lamps and other LED tubes. They have one flat side with two magnets to snap the lamp into place in a ceiling fixture, where it can be wired directly to line voltage. They do not need any lamp holders (aka tombstones), thus removing another potential point of failure since old plastic lamp holders often break during installation of new lamps.
Each of the following two case studies includes a cost breakdown. While the energy savings are significant, remember that the quality and level of lighting are also critical. Do a test of any proposed relamping project to ensure that occupants will embrace the results.
You can view an 8-minute video with more information on these two case studies at www.profitablegreensolutions.com/content/ballast-free-led-retrofits.
Case Study 1: Bank Office Retrofit
My client had 2-foot by 4-foot T-12 recessed fixtures with four lamps behind a lens (see photo 1). Because these lamps were phased out of production in 2014, the client had to make a change.
My routine retrofit would replace the four lamps and two T-12 magnetic ballasts with two new T-8 or T-5 lamps and one ballast (see photo 2). I tested sample fixtures with T-8s in the client’s office. Then, out of curiosity, I also installed a fixture with $25 snap-in LED strips next to the other test fixtures (photo 3).
Ultimately I chose the LEDs for the client’s project. Lighting levels and light quality were improved and energy cut by 65–70%. Although the facility’s operating hours totaled only 2,000 hours per year, the LEDs had a good payback. (See costs at right.)
This LED retrofit doesn’t require recycling of the old sockets, which may be near the end of their useful life anyway. You also don’t need to fit new lamp holders into your old metal fixture since the LED tubes don’t have the two pins at each end. The small magnets on the back of the LED attach easily to the back of the fixture. Installation labor was less because this retrofit had only five steps:
New two-lamp T-8 fixture with reflector
1) Open lens
2) Cut all the wires
3) Remove the ballasts and lamps
4) Snap in the two LED tubes
5) Hardwire the tubes and close the lens
That’s it! In the now vacant space where the T-12 ballasts were attached, I had ample room to contain the wire connections and wire nuts to satisfy our local electrical code.
Aesthetics, Risks and Downsides
For this project, most occupants preferred reading under the LED fixture, probably because the color rendering index was higher (80 CRI) than that of the existing fluorescents (70 CRI).
Many LED strips/tubes come with either a frosted shield or clear plastic. Frosted is best if the strip/tube is visible to the occupants because it reduces the glare and the ability for someone to see the LED sources, which can be too bright for many people. The clear lens is useful for indirect lighting, when the light source is shielded from occupant view.
LEDs are basically tiny computers that are more sensitive to voltage or current fluctuations than fluorescent lamps. During testing, look for flicker when refrigerators, laser printers and other large devices turn on.
New LED tubes
These LEDs had a five-year, unconditional warranty. When they fail, my client will need to replace two $25 LED tubes instead of two $2 fluorescent lamps. However, if the retrofit economics are favorable today, they should be even more so in the future because LED manufacturing costs are falling rapidly.
Existing fixture energy input: 144 watts per four-lamp fixture
LED fixture energy input: 18 watts per two-lamp fixture
LED tube material cost: $25 each
LED installation cost: $15 per fixture
Fixture rebate from local utility (your rebate may vary): $11
Savings per fixture
= [(144 watts/fixture) – (36 watts/fixture)] x 2,000 hours/year
= 216 kWh/year, which equals about $21.60 per year per fixture
in energy savings @ 10 cents/kWh
When projecting your savings from a retrofit, you may want to include savings from reduced labor and HVAC load. But as you can see below, the payback is impressive without these factors.
Installation costs per fixture
= [($25/tube) x (2 tubes)] + ($15 installation) – ($11 rebate)
= $54 per fixture
= ($54/fixture)/($21.60/year in savings)
= 2.5 years
Case Study 2: Ballast-Free LEDs Reduce Energy by 50% in High Bays
In this high-bay retrofit application, I will show the cost advantages of removing T-5HO lamps or T-8 lamps and replacing these with LED tubes on a one-to-one basis. Replacing a relatively new T-5 system with LEDs may seem baffling, but when you’re going from 230 watts per fixture to 96 watts – while doubling lamp life and maintaining brightness – it makes sense to investigate.
If you are unfamiliar with T-bay fixtures, you can find this type of high-bay lighting in many Sam’s Clubs, Walmarts and Costco warehouses.
The building in this application had T-bay fixtures mounted over 20 feet high, each with four 54-watt T-5HO lamps per fixture. The lamps and ballast were consuming about 230 watts per fixture while providing adequate lighting. The retrofit involved removing all four lamps and the ballast, which results in an empty fixture with only the incoming power wires remaining and the empty lamp holders.
Next, the line voltage wires were connected directly to the first LED tube. Connector whip plugs allow the remaining LED tubes to be quickly wired in a series. Within minutes you have four LED tubes mounted where the fluorescent tubes were located. Figure 1 below shows how the LED tubes are connected.
You can also use this installation design to replace 8-foot fluorescent lamps by using a connector whip between two 4-foot LEDs end to end. In that case, you are going from a minimum of 150 watts (two F96T-12 lamps) to only two 4-foot LED strips end to end, which give off enough light and only require 48 watts and no ballast losses.
Aesthetic Benefits, Risks and Downsides
You want to be sure the LED lights aren’t contributing to glare, although this is not typically an issue in high-bay spaces. You should test whether a frosted shield or clear plastic is better for your particular application before doing a whole building retrofit. In many cases, the LEDs will provide a brighter environment with more vibrant colors. Some building managers have chosen to retrofit a six-lamp fluorescent T-bay units with only five LED tubes, which can maintain the light levels while achieving additional savings.
When the LEDs eventually fail, you will be replacing $40 tubes. However, material costs for LEDs are likely to be much less in five years. Even though these LEDs had a five-year unconditional warranty, it is likely they will last about twice as long as the fluorescent systems. The ballast-free LEDs also eliminate a potential point of failure.
I am excited about the simplicity that this LED technology provides. It provides good energy savings and short paybacks, as well as improved lighting conditions. I don’t typically mention brand names in an article, but if you want to learn about these snap-in LED tubes, feel free to email me (firstname.lastname@example.org) and I will provide the name of the manufacturer.
Existing fixture energy input: 230 watts per four-lamp fixture
LED fixture energy input: 24 watts per tube or 96 watts per fixture
Material cost: $40 per LED tube
Installation: $25 per fixture
Electrical demand cost: $7/kW per month
kWh cost: 10 cents/kWh 3,000 operating hours per year
kW savings per fixture
= [(0.230 kW/fixture) –
(0.096 kW/fixture)] x [$7/kW x 12 months/year]
= $11.2 per year in demand (kW) savings
kW savings per fixture
= [(0.230 kW/fixture) – (0.096 kW/fixture)] x [10 cents/kWh
x 3,000 hours/year]
= $40.20/year per fixture in kWh savings
The total dollar savings per fixture would be about $50 per year. However, with such retrofits, you may also want to count the savings on labor and material for relamping as well as the HVAC savings.
Installation Costs per fixture
= ($40/tube x 4 tubes) + ($25 installation)
= $185 per fixture
= ($185/fixture)/($50/fixture/year in savings)
= 3.7 years
In addition, there may be current tax and utility rebates that can help you reduce your payback by 50% or more.
Eric A. Woodroof, Ph.D., is the Chairman of the Board for the Certified Carbon Reduction Manager (CRM) program and he has been a board member of the Certified Energy Manager (CEM) Program since 1999. His clients include government agencies, airports, utilities, cities, universities and foreign governments. In August 2014, he was named to the Association of Energy Engineers (AEE) Energy Managers Hall of Fame.