STAN WALERCZYK CLEP, LC
MARCH 21, 2012
For the numerous lighting retrofit contractors, ESCOs, distributors, consultants, end-customers, rebate administrators and others that have been mainly promoting and specifying lamp for lamp retrofits with 28W or 25W F32T8s or minor delamping with those lamps, please consider the advantages of major delamping, especially with high lumen, which is 3000 – 3100 initial catalog or photopic lumen, 32W F32T8s.
This is especially important since lamp prices have about doubled since the summer of 2011 and may continue to increase.
Although 28W and 25W F32T8s can be used for limited delamping, high lumen 32W F32T8s usually provide the lowest number of lamps, highest energy savings and lowest maintenance costs. Many fixtures with up to 3 basic grade T8s can be delamped down to 1 high lumen 32W F32T8 with upscale kits. There are 1-lamp reflector kits for 2-lamp 2x4 lensed troffers, 2-lamp kits for fixtures that have 2 60W F96T12s and numerous other kit and fixture types.
Although there are several kit manufacturers in North America, it has been my experience that Energy Solutions International (ESI) is more willing to design and offer custom kits at a good price, even for relatively modest quantities, than other manufacturers. Plus ESI has a comprehensive line of standard kits and fixtures. You can compare performance, pricing, lead times, etc. among manufacturers.
Kits are necessary for delamping many fixture types. But numerous fixture types, such 4-lamp 2x4 lensed troffers with interior angled long sides and good cleanable white reflective surfaces and 2-lamp 4’ strip fixtures can be delamped with or without kits. There are pros and cons either way.
High lumen 32W F32T8 is best workhorse lamp, even in non-delamping applications.
FOLLOW THE MONEY
Before I read an article or a white paper, I want to know who the writer is and who paid for it, because that helps understand the credibility and any slant of the document. I am an independent lighting consultant, who has written several white papers. I thank ESI for paying for most of my time on this one, so it can be offered for free, instead of me having to charge people for it. Please be aware, that my major message would be the same if I wrote this totally on my own time or if a different company sponsored it. I cannot risk credibility. Other manufacturers are also mentioned.
REASONS FOR LAMP FOR LAMP RETROFITS
Following are some of the reasons that I have heard during my seminars, consultations, etc. to go lamp for lamp with 28W or 25W F32T8s.
- We look at auditing as a necessary evil, necessary to keep the installers working, and we can audit this way the fastest.
- A qualified lighting professional is not required for the audit and specification.
- This way we do not have to measure, order, receive and install any kits, so we can work faster with less potential headaches.
- As a lamp supplier, our sales volume stays high and we sell these lamps for spot or group relamping.
- A retrofit contractor or an ESCO are not always necessary.
- The best rebates are with these lamps.
- The new lighting is very similar to the old lighting, so nobody should complain.
Regarding the last bullet, if the old lighting was crappy, the new lighting can still be crappy. In general, all of those reasons can be overcome.
It is my opinion that the reduced wattage T8s are better for the lamp manufacturers than for end-customers, because there are good profit margins and sales volume can stay high.
Many people think that they can save 4W with a 28W F32T8 and 7W with a 25W F32T8 compared to a basic grade 32W F32T8, but the savings when driven by most high performance electronic ballasts are more like 2.5 with 28 watters and 5 with 25 watters.
28W and 25W F32T8s should not be used below 60F and do not work well with many older fixed output and dimming electronic ballasts.
One plus for 28W and 25W F32T8s in certain hot applications is that they have optimal light output at 92 – 95F, compared to 77F for 32W F32T8s. But with delamping, which usually results in higher fixture efficiency and lower wattage, which translates to less heat, high performance 32W F32T8 systems can usually outperform reduced wattage T8 systems.
An interesting note is that 4 25W F32T8s with high performance .77 BF ballast consumes about the same wattage and provides about the same simple calculated lumens as 2 high lumen 32W F32T8s with high performance 1.15 – 1.20 BF ballast. But including fixture efficiency with fewer lamps, the 2 full wattage lamps and high BF ballast system usually provides more light. Plus who wants to have to buy, install and recycle 2 extra lamps down the road?
High lumen 32W F32T8s and similar life 28W F32T8s cost about the same, while similar life 25W F32T8s cost more.
Reduced wattage T8s usually do not have sufficient lumens to be used in hibays and other fixtures.
High lumen 32W F32T8s have about the same lumens per watt than 28W or 25W F32T8s, when used with the same electronic ballasts. High performance 32W F32T8 systems also have higher lumens per watt than T5 and T5HO systems. Just dividing initial lumens by lamp wattages from lamp catalogs gives T5s, T5HOs and reduced wattage T8s an artificial advantage over high lumen 32W F32T8s, because the 32W F32T8s are tested with reference magnetic ballasts, while the newer lamp types are tested with reference electronic ballasts, which are more efficient.
28W F32T8s with 1.00 BF ballast provide about as much lumens at about the same wattage as high lumen 32W F32T8 with .87 BF ballast, but 1.00 BF can be more expensive.
For T12, T8 and T5 fluorescents going from standard output to high output increase lumens, but reduce lumens per watt. High performance T8 systems are 8 – 18% more efficient than T5HO systems.
In the fluorescent world, lumens and life fight against each other. So you can get the highest lumens or the longest life, but not both. Sometimes saving every watt is the most important. Sometimes saving the most on maintenance is the most important.
After China really started jacking up the price of rare earth materials necessary in phosphors, at least one major lamp manufacturer has introduced reduced wattage T8s with less phosphors in order to keep the pricing down, but these lamps have less lumens.
The following table should be helpful. B - D columns is information that can be attained from a lamp catalog, but those columns are not that good. E – N columns are much more realistic. I used 2-lamp systems, but 1, 3 or 4-lamp systems could be used. The most important columns are M and N. The lower phosphor lamps are not included.
High lumen 32W F32T8s are the best over-all linear fluorescent lamp, not only because of efficacy.
- When lamp for lamp can use down to .60 BF fixed output ballasts
- Can be used with all older fixed output and dimming T8 ballasts
- Usually better than T5HOs in hibays
- Can be started down to -20F with proper ballasting
- Minimize lamp and ballast types
Lamp minimization can be so important to facility and maintenance departments, because fewer types have to be purchased, stocked and carried around.
If 28W and 25W F32T8s are used in offices, classrooms, etc., usually T5HO lamps and ballasts have to be used in hibays, because the reduced wattage T8s do not usually have sufficient lumens for hibays. So the facility and maintenance people are stuck with two types of lamps and ballasts. High lumen 32W F32T8s can be used almost everywhere.
SPECTRALLY ENHANCED LIGHTING
For those not already aware, spectrally enhanced lighting is basically the benefit of high Kelvin lamps, which have more blue content. Over 80% of my projects have at least 5000K, because I can allow fewer lamps and lower BF. This Department of Energy (DOE) website explains spectrally enhanced lighting, has links to phase 1 and 2 research reports, and has links to several case studies, several of which are mine: http://www1.eere.energy.gov/buildings/spectrally_enhanced.html
Over the last few years, the IES Visual Effects of Lamp Spectral Distribution Committee, which Brian Liebel is the chair and I am a member, has been writing Technical Memorandum 24 on this subject. It has been approved by the IES Technical Review Committee and, after modification, will be sent to the IES Board of Directors. If the Board approves this Technical Matrix, spectrally enhanced lighting will become more accepted and how to use it correctly will become more spelled out, including equivalent visual efficiency (EVE) calculation tools.
WHY BETTER REBATES FOR 28W & 25W F32T8s?
Numerous programs give higher rebates for 28W and 25W F32T8s than for high lumen 32W F32T8s, and some programs only allow these reduced wattage T8s, even though more energy can usually be saved with the high lumen 32W F32T8s.
Often only 28W and 25W F32T8s are included in prescriptive rebate programs, and 32W F32T8s have to be used in customized rebate programs based on how much KWH is saved over the first year. Often, unless there are high annual hours of operation, the rebate is so much higher with the reduced wattage T8s, even if significantly less energy is saved.
Some prescriptive rebate programs only allow up to 50% delamping, which provides a higher rebate for using more 28 or 25W F32T8s than for using fewer high lumen 32W F32T8s, even though there is sufficient light and more savings with the fewer high lumen 32W F32T8s.
Except maybe for emerging technologies, rebate programs should be technology neutral, based on energy savings. I would appreciate any help getting rebate organizations to make their rebate programs fairer.
NO MAN’S LAND
Going lamp for lamp with 28W or 25W F32T8s can save energy, but often after they are installed, there is not sufficient potential savings to go with an optimal solution, such as delamping with high lumen 32W F32T8s and high performance ballast. So maximum energy savings is sacrificed for partial energy savings in this no man’s land.
DELAMPING & LAMP FOR LAMP COMPARISONS
Following are just few examples:
2x4 Lensed Troffer with 2 F34T12s or Basic Grade F32T8s
These troffers can be retrofitted lamp for lamp or delamped as shown here:
A good example of a 1-cove reflector kit is the ESI KT Series 1L Parabolic/Prismatic Troffer Retrofit Kit.
The bolded columns in this table are the most important. Visually effective lumens are based on spectrally enhanced lighting. If maintaining existing light levels is important the two gray background options are probably the best. Since payback does not include any benefit after payback period, and there is usually more benefit after payback, the long term benefit column is much better. Net present value, modified internal rate of return and savings to investment ratio are even better financial tools.
2x4 Lensed Troffer with 3 or 4 F34T12s or Basic Grade F32T8s
These troffers are worse than 2-lampers, because these have less efficiency, because there are usually 2 lamps in 1 reflective compartment with nothing between the lamps, so light is wasted bouncing directly between pairs of lamps and indirectly from lamp’s light hitting the reflective housing and then hitting the other lamp. Unless these fixtures are air handlers, the heat from the lamps and ballasting can bring the ambient air temperature in the lamp compartment to about 100F or even higher.
Delamping down to 2 better T8s and high performance ballast can bring the temperature down in non-air handler troffers much closer to the optimal 77F for full wattage T8s. Delamping also only has 1 lamp in a each reflective chamber, which increases fixture efficiency.
If the long interior sides are angled and if the original white paint or powder coating is in good shape, often a reflector kit is not necessary with delamping to 2 lamps. Often the existing outboard lamp holders can be used, and for rebate purposes, the inner lamp holders can be removed. Although this will provide sufficient light, the lamps are usually not centered, which is okay for some end-customers. Sometimes a higher BF is required without a reflector.
If the existing troffers do not have angled long interior sides and if the reflective surfaces are in not good shape and cannot be cleaned, reflectors should be used with delamping. If the end-customer wants centered lamps for aesthetics, a reflector or centering-bracket kit should be used.
2x2 Lensed Troffer with 2 U-bend T12s or T8s
Although every facility manager and maintenance person, who I have communicated with, has wanted to get rid of U-bend lamps because of cost and bulkiness, there are still some retrofit contractors and others that want to retrofit these fixtures with reduced wattage U-bend T8s.
The best retrofit is usually a 2-cove white reflector kit, 2 high lumen 17W F17T8s and a .87 – 1.15 BF high performance ballast. The reflector is necessary to get power to both sides of the fixture. The BF depends on how much light is needed.
8’ Strip with 2 60W F96T12CWs
Almost every facility manager and maintenance person wants to get rid of 8’ lamps, but some retrofit contractors and others want to retrofit these fixtures lamp for lamp with full or reduced wattage 8’ T8s. A kit is necessary to convert this fixture with 4’ T8s.
If the existing up and side light is important, it can be a strip kit. To provide as much light as existing the best solution is usually 2 high lumen 32W F32T8s and high performance 1.15 – 1.20 BF ballast, which reduces wattage from about 123 to 70 – 72.
If the existing up and side light is really wasted light, then it can be a deep or shallow hooded industrial reflector kit. Often 2 high lumen 32W F32T8s and .71 - .89 BF high performance ballast works the best, maintaining existing light levels where needed and reducing wattage from 123 to 46 – 60.
8’ Strip with 4 F34T12s or basic grade F32T8s
This is similar to above, but another option is delamping without a kit and installing 2 lamps in opposite corners.
2x4 18 Cell Parabolic Troffer with 3 F34T12s or Basic Grade F32T8s
Parabolic troffers were popular in the late 80s and early 90s, when computers became popular in offices. Those computers had curved screens without anti-glare coating. Parabolics helped. But now computer screens are flat and have anti-glare coating. The downsides of parabolic troffers are currently known.
- Dreaded cave effect from dark ceilings and upper walls, which makes the space seem dark and smaller
- 70 – 75% fixture efficiency
- Lack of vertical footcandles
- Overhead glare, which can cause eye strain and headaches
Here is one example of an office worker hating parabolic troffers:
The maintenance person told me that it took 2 months to get this office worker to take down the tent.
Some retrofitters and others go lamp for lamp with 28W or 25W F32T8s, but that keeps all of the listed downsides of parabolics.
Some retrofitters and others go for 2-cove white reflector and 2 high lumen 32W or reduced wattage F32T8s. Light levels can be okay, but for office applications, this ruins proper cut-off angles, which can create a glare bomb. Plus if a specular reflector is used, the fixture looks like a house of mirrors.
Replacing parabolic louvers with upscale kits is a great way to do an upgrade, and usually a retrofit without an upgrade is a wasted opportunity.
ESI’s Direct/Indirect Troffer Kit greatly improves lighting quality and greatly reduces wattage in parabolic troffers. Up to 3 F34T12s or basic grade T8s can be replaced with 1 high lumen 32W F32T8. If 5000 or higher Kelvin is used, the BF may be as low as .87. This kit can also be used with 28W or 25W F32T8s, T5s and T5HOs.
Some customers want low prices, even if performance suffers. But with proper design fewer lamps and/or lower BF can be used to save more energy, which is really a better solution.
One way some manufacturers try to keep costs down is to design most or all reflectors for smaller diameter T5s and T5HOs and then also use those same reflectors with larger diameter T8s, which reduces efficiency and optical control with T8s.
ESI and some manufacturers have commodity grade reflector kits, hibays and other fixtures, and also more expensive spec grade kits and fixtures, which are usually a better total value, because more wattage can be saved cost effectively. For example, I usually only recommend reflectors for T8s that are at least 4” nominally wide, which can be down to 3.75” wide and the reflector should protrude further than the lamp. Also there should be only 1 lamp per reflector cove.
One example of a good T8 high bay is the ESI Premium HS Series.
Over the years in typical offices, classrooms and halls, specular reflectors have been more popular in the east and white reflectors have been more popular in the west. For most of these applications, white is better, because less glare, better uniformity, and not seeing the reflector bends on the lens.
There are mainly two types of white reflector, which can be called prepaint and white powder coat. Prepaint is usually less expensive and has slightly less reflectivity. White powder coat can be considered more environmentally friendly, because no paint thinners or solvents.
For high heights specular is usually the best. For mid heights in gyms, retail stores and conference centers often the best material is Alanod’s Micro Matt, which looks white for less glare, but has the optical control of specular.
In addition to ESI, some other reflector kit, lamp holder kit, fluorescent hibay and other fixture manufacturers, that you may already know about include:
- Precision – Paragon
- Lithonia, Daybrite and some other large manufacturers that have gotten into kits because the new construction market is so bad
If you get a quote from any of these other manufacturers, please check what ESI can do for you.
FUTURE IS BECOMING NOW
Check out ESI’s current and upcoming LED kits and fixtures. The 2x2 and 2x4 LED fixtures and retrofits are available now. ESI also has other LED fixtures, including:
- CA Series LED Lowbay Fixture
- HB Series LED Retail High Bay
- WP Series LED Wallpack
ESI CONTACT INFORMATION
ABOUT THE AUTHOR
Stan Walerczyk is principal of Lighting Wizards, an independent energy efficiency consulting firm. His 23 years lighting experience includes distribution, maintenance, retrofit contracting, 3rd party review, consulting, design and research. He has been assisting on DOE research on spectrally/scotopically enhanced lighting. He is a DOE CALiPER Guidance Committee member on LED products. He has written over 30 published papers and presented over 700 seminars, including in 2011 speaking twice at Lightfair and ArchLED and all day at WEEC. His Advanced Lighting Retrofit Options, Interiors – LED vs. Incumbents and How Low Can You Go seminars further discuss the benefits of delamping with high lumen 32W F32T8s. He is a Certified Lighting Energy Professional by the Association of Energy Engineers and is Lighting Certified by the National Council on Qualifications for the Lighting Professions. He was a member of the Illuminating Engineering Society from 1995 to 2008 and is currently on its Visual Effects of Lamp Spectral Distribution and Energy Management Committees. Complete bio, seminar schedule, testimonials and other information are available at www.lightingwizards.com.
These are all of his free white papers, which are downloadable:
- EHID & LED For Exterior, Hibays, Etc.
- High Bay Occupancy Sensors: A Comparison
- How to Retrofit Parabolic Troffers
- LED vs. Induction – Full Cut-Off Streetlights, Etc.
STAN’S LAST WORDS
Please avoid induction and LED T8s.