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Currently the most cost effective solution is standard fluorescent fixtures using 6500k tubes. CFL of the same color work well also. Fluorescents produce about 4 times as much light as incandescents do for the same power. LEDs are about the same but cost a lot more right now.
Good LED lights are very expensive but have a very long life and more efficient than fluorescent for the energy consumed.
A recent article in Fine Gardening magazine ran a test on seed growing under several light sources. The expensive LED had the best results (but the lights ranged from $700 to $1400). They had 2 different cheap LED lights (they came in at the bottom), 3 different fluorescent tubes - two different T5 (HO) systems and a T12 standard shop light, and 4 Agrosun incandescent bulbs. The standard shop light came in second best. They grew 9 different plants from seed for five weeks and measured survival rate of the plants and the weight of the harvested plant (not the most scientific but beats nothing). The temps were regulated and the lights were run 14 hours a day.
No the old T12's will be eventually phased out and you are correct that T8 and T5 are more (what does MUCH really mean?) efficient = providing more lumens for less power.
LED lights are more efficient than fluorescent but not all LED lights are equal - you often get what you pay for. The ones in the FG magazine that were affordable came in at the bottom of the performance chart.
We've replaced our can lights with LED bulbs (they use about 1/10 of an incandescent light's power consumption) and they are amazing but expensive with bulbs running 30 to 40 dollars a piece. I really like these lights since they are instant on unlike CFL and are very bright. So we have done 9 in the kitchen and 3 in the basement so far.
Then we started replacing hallway and bathroom regular 60 to 100 W lights with LED lights. At around $15 a pop this can add up quickly compared to incandescent or CFL. Now a lot of these lights just stop working. It's like they heat up and turn off then may come on again later on. This is terrible for the next generation lights. We probably have 15 of these so far and I won't buy anymore until they insure that LED lights will work non stop for the 18 - 22 years they say they will work. We just replaced a few with CFL that we tried to get rid of by going to LED. Not good.
As your oldies slowly quit working (bulbs or ballast) I would replace them with T8 or T5. I have been in the process of replacing my T12's over the last 4 years with T8's as the T12 quits working (usually one side will quit) or as the bulbs burn out (I am not planning on buying any more T12 bulbs). If the fixture is bad then it is going to the trash. If the bulbs burn out I donate the fixture to anyone who wants a freebie. I am running about 75 lights and have replaced over 60 so far. Just a few more to go.
>> correct that T8 and T5 are more (what does MUCH really mean?)
I'll toss out "40% more efficient than old-style T12s" as a ballpark number.
But it depends on what you're comparing to what.
really old-style T12s (1930s technology) = 32 or 40 W 2,100 - 2,800 lumens = around 68 +/- 15lumens / Watt
cheapest or average or high-efficiency or high-output or long-life modern T12s
cheapest T8s and T5s
"average" T8s or T5s - - around 95 lumens per Watt
high-efficiency T8s or T5s
high-output T8s or T5s
long-life T8s or T5s.
For a real efficiency comparison, you would have to specify exact model numbers for each tube, and only compare new bulbs to new bulbs.
Some ballpark numbers I came up with from manufacturers' ratings:
old-style T12s were around 2.5 X as efficient as incandescent
\normal T8s around 1.4 X as efficient as old T12s.
old-style T12s around 68 lumens / Watt
normal T8s around 95 lumens per Watt
Allegedly fluorescent bulbs lose a lot of intensity over a year. Some commercial grower recommends changing all bulbs every six months (seems wasteful). I certainly won't do that. The bulb has to flicker or look very dim to me to change it out. The plant growth is the best indicator. and as long as they look good then I will keep the bulbs. Call me cheap!
I don't know if anyone is running lights 24 hours but anything is possible. The guy was talking about hobbyists changing lights out every six months, a year at the most. He said he had no stock in the light bulb manufacturers too (ha).
Seems like a professional grower would be using HID or as much sun as they can garner. If money was no object, then...
I think his specialty is herbs and poinsettias for the Xmas season.
Not sure what lights he uses if any since he has greenhouses. I think he did a term paper on lights when he was in college decades ago.
I hope light design has changed since he did his study but if not then I am still trying to be economical by not jumping on the newest thing. If we swapped every time something new came out we might be broke and also sorely disappointed when the new stuff didn't work as advertised.
So when will they be phasing out the T12 units? (Guess I should stock up on them since I have boxes of the T12 bulbs?) Has anyone ever changed out the ballast, how hard is it and how much do they cost? I have 36 T12 light fixtures which are only in use from Dec-April for starting seedlings. I've eyed the newer units but the $$$ are prohibitive... If and when I ever get done creating new gardens maybe the newer units won't seem soooo expensive.. But til then I've got quite an investment. in both stands and lighting...
Not sure exactly when they phase out T12 - thought it was underway. Ballasts are not hard to change out - a few wiring connection, and bolt the new one in place. Color coded wiring and simple directions. The problem is sometimes the ballast cost as much as a new fixture but then maybe the ballast is better than the new fixture's ballast?
Just looked up the phase out - it was supposed to begin July 14, 2012! So if you find any old T12 fixtures you better buy them if that is what you really, really want to stay with. You can always look for people who are giving away their old fixtures as well.
I would phase out any old T12's that use magnetic ballast as they go "bad" and buy new T8 or T5 that use electronic ballast. Last longer (allegedly) and also make the bulbs last longer too.
I go for cheap fixtures - it was about $12 to $14 for a T12 fixture and about $20 for a T8 fixture (shop light). Bulbs are a little cheaper if you buy them in 20 to 30 per case (less than $2 a bulb). The energy savings and slightly better light output should pay for itself in less than a year. If your energy rates are 10 cents per KW then 30 days * 12 hours a day would save you 58 cents of a T8 over a T12 (two 32 watt bulbs vs. two 40 watt bulbs). To make up the $8 would take about 14 months while to make up $6 difference in the cost of fixtures would take about ten months. If you go with T5 HO expect to pay more for the fixtures, bulbs, and energy costs.
I still have 2 full boxes of T12 bulbs yet, think I'm good on bulbs for a while (20 yrs) LOL.
Thanks for the info on ballasts, I may have to head over to H.D. and see if I can find one to try it. I've just bought a new unit when they get persnickity. Always thought that was such a waste tho.
I would think if they were sincere about phasing them out they'ld put them o sale to get rid of them. Was there a date included in the info you found as to a final date that they are suppose to be off the market??
I built my plant stands with the T12 in mind too. My first unit is 61" long and the one I made last year is 71" long. The maximuum space for 1020 trays or half trays, 7 1/2 trays per shelf on the smaller unit, that's 240 plants per 2 units...(of course it depends on the trays I use or should I say size of pot.
It's really not a stop making T12s as much as you must meet this minimum lumens/watt goal. I'm not sure why a smaller diameter makes for a more efficient light or maybe it's just that the newer technology goes with the smaller diameter tubes.
>> it's just that the newer technology goes with the smaller diameter tubes.
The T8 and T5 bulbs use "CFL" technology (Compact Florescent Light"). I've read that the T12 technology goes back to the 1930s, almost unchanged.
>> Maybe in another 20 years it will be a Mylar strip you tape up and get all your light with zero headroom running off low voltage (just dreaming).
If you change "Mylar" to "LED" and "20 years" to "now", I think you have it exactly right. The light-emitting part is really thin, and new homes may have it installed as if "painted on" walls and ceilings.
Of course there is a catch: right now it is still really expensive.
If they do it's likely to be a byproduct of solar cell technology. I expect that fluorescents to be around a long time. After all they've been around since the 1930's and have just ended incandescent lighting.
I wonder about the odd shaped incandescent bulbs for chandeliers, ovens, microwaves, refrigerators, and the big decorative bulbs over bathroom sinks. I haven't seen replacements in CFL or LED for these specialty lights yet. Light manufacturers need to get on the ball.
LED lights have to improve to where they live up to their long life claims as well. People are going to get pretty upset if they spend $15 on a bulb that quits after a few months. It is bad enough spending a dollar or two on an incandescent bulb that quits after a few days.