Effiency race... is it necessary ?

Less to do with zone.
Everything to do with insulation/ambient temps.

Are you growing in an garage in Alaska? A converted walk-in fridge in Arizona? A tent in your bedroom?

You're still better off using a space heater to augment your temps and taking advantage of the spectrum/spread of LED's than using HPS.

What is more expensive to purchase/run... A space heater in the winter or a minisplit in the summer?

The fact is, an LED lamp is a better tool than a high pressure sodium lamp. The less you have to rely on exhaust to control your temps especially if you run co2, the better.

The only leg HPS has left to stand on is price and as the price of quality LED's goes through the floor....well you know how this story ends....

ChaosHunter said:

I have my driver plugged into a Kill-A-Watt and use it to dial in what I want the output to be.

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Do you know how the efficiency changes as you change the Kill-A-Watt?

If I can max out the intensity of light without having to use AC I'll be happy. People talk about grams per watt and you rarely see them include air conditioning into that measument.

This measument doesn't even include the initial investment and installation, maintenance, ability or requirements to conceal or environmental monitoring and possible breakdowns associated with it. Not having to deal with air conditioning at all is a huge tangible.

This is most certainly not everbodies situation, but the difference in heat between a hps and uber efficient led should be taken into consideration. I'll install central air to the whole house and double the cobs to gain efficiency if it eliminates the need to consider another costly environmental factor.

tstick said:

I would like to see a new kind of "ratcheted" dimmer that would "click" as you turned it ....and/or some kind of markings to indicate the position of the knob and what output corresponds to that position.

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Use a 12 position Nob check out "3in1 dimming" thread from stardust.



Here I gave you a scientific study showing you that LED need at least 80F ambiant Temp to achieve a good efficiency, maybe even 84F is using monos. I wanted to discuss if really more efficient light means more efficient overall system, and if efficiency is still the limiting factor in our set up...

I will make an example to illustrate better the point I want to discuss:

I have a 1x1x2m box. I maximise my light because I have a high Co2 level in my place and I want to make as much weed as possible in my box. So I need about 350W PAR (about 1500PPFD with 3500K cob). I also need extraction for my plant to breeze, say the minimum is to extract the volume of the box every minutes it make about 150m3/h

In terms of parameters I want 85F for ambiant temp, not less, otherwise, as the paper show, Leaf Surface Temperature become too low and it photosynthesis drop.

I want to achieve all these ideal parameters and spend the less possible money - investment and elec bill needs to be taken into account.

So

1. I get a 40% eff LED lamp, I will need 875W of light in my room, and I will get 525W of heat.
2. I get a 50% eff LED I will need 700W and get 350W electricity bill goes down by 20% here, initial investment goes up.

At this point we make the assumption that this to light enable me to reach this 84F temp, hence I better go with the 50% eff LED. We all agree !!!

But now let's continue the race as it is happening,
>>>>>3. I go for 65% eff LED lamp, then I use only 540W that give me 188W of heat. I put a lot of initial investment because it is way more expensive than 50% eff, but electricity bill is reduce by 22% compare to 50% eff and 38% from my initial 40% eff Light so I will recover my money. Great !

Problem, there is not enough heat with only 188W, my temp in the room goes down to 80F, the plant grow less and they don't use the 350W of PAR light as efficiently as before.
Ouch !!! It means I invested a lot of money to get 5% more efficiency but because of f... Temperature my plants grow 5% more slow... Operation is null and I losed money. Even worst, if race continu to the point temperature is too low, I might pay a lot of $ for 5% percent but the plant will have a metabolism reduced by say 10 or 15% percent.

Why is that ? because the limiting factor here is temperature ! not light, not Co2 not any thing else anymore.

Solutions ?
I decrease the extraction =>> no, we assume it was already at the minimum.
I add heater => it add cost, electricity bill, and my 65% efficiency LED costed me a lot more money than the 50%...

reduce LED efficiency => less investment, more electricity bill but ideal on all the other parameters. It is called a hit, the sweet spot. It will be different for different application, but again I think 65% efficiency might not be better than 55% depending of your case.

Now let's find this sweet spot

I presented it like a Maths system because it really is actually.
But is more something I experienced, improving each year my COB...
I am geek tech anyway and will continue to do so, but still, no need for weapon race in LED grow rooms

speedyganga said:

Hi everyone,

I ressently read this article and some others on the Leaf Surface Temperature comparaison between LED burble vs white, LED vs neon and LED vs HPS.

I was shooting for 75F in my grow room when using HPS, and when I made the switch to Led, and then COB, I kept my habits. After reading this article, I started raising the Air temp to 80F and saw higher growth, so I went up to 85F by reducing a lot the extraction. So far plants respond better than at 70F and I intent to keep runing my grow at 82-85F for now on.

Now, we all sicks more efficient COB and while I feel that is great, I think we are already at the limit...
Lamp needs to heat the grow room as well as provide light.
If let say you spend high $ on a 80% efficient LED, and you need to add a low efficiency heater in the room to achieve the correct temperature and you run a huge and expensive extrcation fan, Is that still efficient ?

Because HPS output lot of IR we needed strong extraction. When room temp is at 70F the LST is actually around 83F.
With Led we can reduce the extraction to what is needed for the plant - i.e the volume of the room extracted 4-8 times per hour - and rise the room temp at 80F to achieve this ideal 83F LST.
Right now, I have a LED lamp around 55% efficient in my box, and I have sometimes difficulties to reach this 80F degrees.

So let me ask:
what is the point to pay $$ for 60% efficient LED if I need to add a heater ?
What is the point to have 60% efficient LED if plant metabolism is low in the room ?

Isn't 50% and "great spectrum" sufficient in most of our application ?
At 40% efficiency, LED are already better than HPS due to their adapted spectrum, going to 50% enable us to reduce electricity cost and extraction speed, but above that, depending on the Temperatures in your place I don't think you actually benefit of the $$ you invest.

Please guys, let's discuss this issue

I also think while people switch from HPS to LED, they do not use their LED to full efficiency. For 2 years now, I changed the way I water, the nutrients regimen, the room temperature etc...
We should start to talk more about these, instead of numbers and BS around LED brand. Truth is, I saw some guys doing great grow under any lighting, providing they dialed in the environment...
-----------LET'S TALK GROWING----------- under LED


peace

Click to expand...

Mine runs at 61% efficient and holds the room at 75F with out any air exchange. The thing is if you run a sealed room with LED it's a benifit to not need much cooling. Run co2 and more LEDs bring the temp up.

Co2 generators are a perfect solution. Warm up the room a bit as a byproduct and use the crazy amount of PPFD you can get to push the room hard. That's my goal at least in the next 2 years.

I'm in Michigan, it's cold out... To be fair that test was ran in the summer. I should re run it lol.

speedyganga said:

I think 65% efficiency might not be better than 55%

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You can maintain the same temp with the same wattage and get more light with the 65% efficiency option. The light is converted to heat at some point, so 100w of 65% efficient light will produce similar heat as 100w of 55% efficient light.

Rahz said:

You can maintain the same temp with the same wattage and get more light with the 65% efficiency option. The light is converted to heat at some point, so 100w of 65% efficient light will produce similar heat as 100w of 55% efficient light.

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Yes, very true Rahz , but...
Why would I run 100W at 65% ? I said before, max PPFD achieved for every efficency, if I run at 65% I reduce the total power.
if the room needs 50W PAR to be max out I will run 100W @ 50% but only 67,5W @65% and this is where I was saying at some point there is a heat problem...

Numbers I took are just for the sakes of example, I don't know where is the limit where efficiency is not a limiting factor anymore. I guess LED maker themselves will soon stop this race to concentrate on uniformity, shapes, and other as important parameters

speedyganga said:

Yes, very true Rahz , but...
Why would I run 100W at 65% ? I said before, max PPFD achieved for every efficency, if I run at 65% I reduce the total power.
if the room needs 50W PAR to be max out I will run 100W @ 50% but only 67,5W @65% and this is where I was saying at some point there is a heat problem...

Numbers I took are just for the sakes of example, I don't know where is the limit where efficiency is not a limiting factor anymore. I guess LED maker themselves will soon stop this race to concentrate on uniformity, shapes, and other as important parameters

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The point is you can get the same light for less wattage. People assume WATTS is how much light you get... When in part that's true, but the real answer is that that's not the only part of the equation. That extra efficiency will manifest itself as a better g/W number pretty much every time all things the same

I think efficiency is often way overrated and incorrectly interpreted. Increasing efficacy by running the COBs softer increases the initial investment quite dramatically relative to the small extra cost savings you get in electricity cost.

It's better to calculate what the cheapest efficacy is for your kWh price over a certain period of time . For me that's around 2.3umol/s/W.

If I go lower, the electricity costs start to outweigh the initial cost savings within 18 months. If I go for higher efficacy it takes about 4 years to recover the extra expenditure in COBs by savings in electricity. It really is quite a sharp peak.

With prices dropping at the speed they are at the moment, I'd rather err on the side of lower efficacy anyway.

Also don't assume bigger COBs are more efficient. Of course they are when all COBs are compared at 50W, but in the end they can all run at 2.3umol/s/W. Just find the current/watts where each model COB reaches the efficacy you picked and you can compare all of them on equal power cost.

speedyganga said:

Yes, very true Rahz , but...
Why would I run 100W at 65% ? I said before, max PPFD achieved for every efficency, if I run at 65% I reduce the total power.
if the room needs 50W PAR to be max out I will run 100W @ 50% but only 67,5W @65% and this is where I was saying at some point there is a heat problem...

Numbers I took are just for the sakes of example, I don't know where is the limit where efficiency is not a limiting factor anymore. I guess LED maker themselves will soon stop this race to concentrate on uniformity, shapes, and other as important parameters

Click to expand...

That's true. I run on the assumption that most people aren't building 1300 PPFD lamps. Between 800 and 1000 has been the generally accepted happy medium and most lamps today have that as their level in the target footprint, so bumping up the efficiency with the same wattage is still appealing for many.

Yep, I like to grow the max out of my space, I don't have much so I can't dedicate a entire room or basement like you guys do in US.
Did you try going at 1300ppfd and up ? Find plants really enjoy it ! they just grow stronger
But It make sense I could maybe lower my intensity and harvest the same, I need heat right now anyway...

The most I've used is about 780. 800 is excellent when there's plenty of space but yes most people aren't in that situation.

speedyganga said:

Yep, I like to grow the max out of my space, I don't have much so I can't dedicate a entire room or basement like you guys do in US.
Did you try going at 1300ppfd and up ? Find plants really enjoy it ! they just grow stronger
But It make sense I could maybe lower my intensity and harvest the same, I need heat right now anyway...

Click to expand...

I'm in the same situation as you. My climate in the U.S. Pacific Northwest creates a situation where my 3ft x 3ft grow closet tends to be too cool right now with LEDs. Temps are around 73 - 75F. I decided to go with a 50% efficient light (800 ppfd) with the thought I would want a bit of heat from it. But, I have been surprised at how cool the closet is. I put the exhaust fan on a speed controller, but that only raised the temps up to around 77F and 40% RH. So, I put the exhaust fan on a timer and run it on a cycle of 15 minutes on, 15 minutes off. This puts temps at 77F - 85F and 40 - 75% RH. So, I figure average temp is 81F and average humidity is 60%. Leaf temps have been 78 - 80F. I'm wondering if maybe this fluctuation might be good for the plants... or bad? But, I figured it was worth a try to get temps up. I may eventually add a few more COBs to increase temps and get the added benefit of extra ppfd. Although, at some point the plants can't use the extra ppfd, and I don't run CO2.

PDX Joe said:

I'm in the same situation as you. My climate in the U.S. Pacific Northwest creates a situation where my 3ft x 3ft grow closet tends to be too cool right now with LEDs. Temps are around 73 - 75F. I decided to go with a 50% efficient light (800 ppfd) with the thought I would want a bit of heat from it. But, I have been surprised at how cool the closet is. I put the exhaust fan on a speed controller, but that only raised the temps up to around 77F and 40% RH. So, I put the exhaust fan on a timer and run it on a cycle of 15 minutes on, 15 minutes off. This puts temps at 77F - 85F and 40 - 75% RH. So, I figure average temp is 81F and average humidity is 60%. Leaf temps have been 78 - 80F. I'm wondering if maybe this fluctuation might be good for the plants... or bad? But, I figured it was worth a try to get temps up. I may eventually add a few more COBs to increase temps and get the added benefit of extra ppfd. Although, at some point the plants can't use the extra ppfd, and I don't run CO2.

Click to expand...

The heat from LEDs comes out the vents and is generally sucked up towards the exhaust. A small fan above the lamp tilted downward can help move some of the heat below the canopy. Doing the exhaust in reverse can also increase temps below the lamp rather than above.

Rahz said:

The heat from LEDs comes out the vents and is generally sucked up towards the exhaust. A small fan above the lamp tilted downward can help move some of the heat below the canopy. Doing the exhaust in reverse can also increase temps below the lamp rather than above.

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Yes, I did this too with the oscillating fan and it does seem to help a bit. I think it raised temps around the plants by a couple degrees.

active light engines blowing warm air down on canopy could be useful for this

CobKits said:

active light engines blowing warm air down on canopy could be useful for this

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Hummm... using an air cooled hood to warm fresh air inlet would be really cool. Using all the resources from the light, not only its photons but also recovering the wasted energy/heat.

Unfortunately for me, that's not an option. When the outside temps are 90-100f, you want as much efficiency as you can get. I would love a chip that would transform ambient heat into light and make the place cooler. If I could use only 100w of light, I could invest in a small thermoelectric AC, like a bigger brother of those wine coolers, and would solve ambient heat issues without using too much power(around 150w to cool the intake air).

If you are using your lamp as a heater, you are not looking into efficiency at all since the lamp is not the most efficient heater. There are products designed specially for that that have a higher efficiency and you will end up paying less on your electrical/gas bill.

"Oh, there is too much light and not enough heat": Have you considered a burner to generate the CO2 that your plants will need because of so much light ? Won't that burner help with your low temp issues ?

Now, one thing for sure: It will requires you to pay more upfront, as any high efficiency system. But will save you later on the bills.

Good question, I've seen a few comments related to using the tech where appropriate which is what I'd recommend. The overall environment is as or more important than the lighting tech and if you have to jump through too many hoops to dial any lighting tech, to me it's not worthwhile nor the appropriate tech for your specific environment.

That said I'd stick with COBs after a few runs just for the quality, even if it cost the same to run. BUT, I'll use my CMH hood through winter likely for the extra heat and mix it with LED for the free heat and bringing my environment to where I want it if I need the heat. Probably won't need it in my case because I hooked into my HVAC in my flower room so I get AC in summer or heat in winter for the cost of running an inline fan with a variable controller. It essentially lets me "dial-in" by turning the variable controller up/down as needed.

GroErr said:

Good question, I've seen a few comments related to using the tech where appropriate which is what I'd recommend. The overall environment is as or more important than the lighting tech and if you have to jump through too many hoops to dial any lighting tech, to me it's not worthwhile nor the appropriate tech for your specific environment.

That said I'd stick with COBs after a few runs just for the quality, even if it cost the same to run. BUT, I'll use my CMH hood through winter likely for the extra heat and mix it with LED for the free heat and bringing my environment to where I want it if I need the heat. Probably won't need it in my case because I hooked into my HVAC in my flower room so I get AC in summer or heat in winter for the cost of running an inline fan with a variable controller. It essentially lets me "dial-in" by turning the variable controller up/down as needed.

Click to expand...

You could run a few cobs harder in winter, it will provide you good light and more heat...

PDX Joe said:

I'm in the same situation as you. My climate in the U.S. Pacific Northwest creates a situation where my 3ft x 3ft grow closet tends to be too cool right now with LEDs. Temps are around 73 - 75F. I decided to go with a 50% efficient light (800 ppfd) with the thought I would want a bit of heat from it. But, I have been surprised at how cool the closet is. I put the exhaust fan on a speed controller, but that only raised the temps up to around 77F and 40% RH. So, I put the exhaust fan on a timer and run it on a cycle of 15 minutes on, 15 minutes off. This puts temps at 77F - 85F and 40 - 75% RH. So, I figure average temp is 81F and average humidity is 60%. Leaf temps have been 78 - 80F. I'm wondering if maybe this fluctuation might be good for the plants... or bad? But, I figured it was worth a try to get temps up. I may eventually add a few more COBs to increase temps and get the added benefit of extra ppfd. Although, at some point the plants can't use the extra ppfd, and I don't run CO2.

Click to expand...

In my opinion a steady environnent is the best.
I grow SOG with 1-4 plants a sq foot depending on hydro or soil, so increasing PPFD and defoliation helps me a lot to achieve big yields in a small surface. Depending on your grow method you could benefit more or less from more light, but you will for sure always benefit from more light.
Maybe increase PPFD to 1200, but don't add new cobs, just run the one you have a little harder, they will heat the space more efficiently and you will have minimal investment.