Lighting How to calculate BTU's, Watts do not automatically = heat!!!

[Black Sail]

There are a lot of myths and rumors flying around about LED's, and I consider it a serious problem. My fellow growers are getting ripped off every single day by LED manufacturers due to bad information or no information at all.

At BlackSail we're trying our hardest to help growers make informed decisions!
The truth is our first priority.



The myth that any fixture with the same wattage will produce the same amount of heat regardless of efficiency is wrong. Here's why:

Newton's First Law of Thermodynamics:

In plain english:

Yes, one watt will always create 3.4 BTU's of heat, but only if it's being turned into heat! If you have a more efficient fixture that turns more watts into light, it must be turning less watts into heat!!!


Let's do an example, take a look at that first equation.
U(energy coming in) = Q(heat coming out) + W(light coming out).

U = the energy being added, ie the Wattage
Q = the change in temperature (the heat produced)
W = the work being done, in this case making light. W is a negative number because the energy is leaving the system as light

You have to subtract the number of Watts being turned into light from the total wattage, and only the remaining watts become heat!




Here's an example, a 1000W Double Ended HPS is about 30% efficient. So 300 Watts become light, and the remaining 700W become heat:

1000W (U, energy in) = 700W (Q, Heat) + 300W(W, light)

700W (Q, Heat) x 3.4 (BTU's per Watt) = 2380 BTU's from a 1000W fixture




Now, on a 1000W High Quality COB fixture that's about 50% efficient you get 500W becoming light. That means there's only 500 Watts left to become heat!

1000W (U, energy in) = 500W (Q, Heat) + 500W(W, light)

500W (Q, Heat) x 3.4 (BTU's per Watt) = 1700 BTU's from a 1000W fixture

With the same wattage coming in, more light coming out must mean less heat coming out! Heat and light both contain Energy, and Energy doesn't come from nowhere!

 

[HashMaster]

There are a lot of myths and rumors flying around about LED's, and I consider it a serious problem. My fellow growers are getting ripped off every single day by LED manufacturers due to bad information or no information at all.

At BlackSail we're trying our hardest to help growers make informed decisions, which is why I was so upset to see a trusted LED manufacturer spreading false information on my Instagram:

View attachment 973934



Sorry to put you on blast @BigSm0 but just because you hear someone say something and repeat it, that doesn't make it a fact!

If you have a science/math/fact based issue with what I'm saying please explain it to me. Here at BlackSail the truth is our first priority.



This is why I think you're wrong:

The first law of thermodynamics:

In plain english:

View attachment 973923

Yes, one watt will always create 3.4 BTU's of heat, but only if it's being turned into heat! If you have a more efficient fixture that turns more watts into light, it must be turning less watts into heat!!!


Let's do an example, take a look at that first equation.
U(energy coming in) = Q(heat coming out) + W(light coming out).

U = the energy being added, ie the Wattage
Q = the change in temperature (the heat produced)
W = the work being done, in this case making light. W is a negative number because the energy is leaving the system as light

You have to subtract the number of Watts being turned into light from the total wattage, and only the remaining watts become heat!




Here's an example, a 1000W Double Ended HPS is about 30% efficient. So 300 Watts become light, and the remaining 700W become heat:

1000W (U, energy in) = 700W (Q, Heat) + 300W(W, light)

700W (Q, Heat) x 3.4 (BTU's per Watt) = 2380 BTU's from a 1000W fixture




Now, on a 1000W High Quality COB fixture that's about 50% efficient you get 500W becoming light. That means there's only 500 Watts left to become heat!

1000W (U, energy in) = 500W (Q, Heat) + 500W(W, light)

500W (Q, Heat) x 3.4 (BTU's per Watt) = 1700 BTU's from a 1000W fixture

With the same wattage coming in, more light coming out must mean less heat coming out! Heat and light both contain Energy, and Energy doesn't come from nowhere!

What does the light energy become ?

 

[hairyman]

 

[Black Sail]

What does the light energy become ?

Photons, and then weed!

 

[Black Sail]

Hahahaa, I'll try to keep it family-friendly and put on a good show

 

[hairyman]

Wouldn't the light result in a exothermic reaction where energy is released as heat ,, just kidding I know Jack ,, but very intresting

 

[HashMaster]

Photons, and then weed!

Full disclosure, I'm a busted up old fart who runs HID. Always will. But This thread caught my eye before my Morning bowl of hash and made me go hmmmmm..... hence my question.

So, here is why I asked it: when light energy is absorbed in my system some of it becomes heat. For example a black pot getting warmer, the floor getting warmer, etc.

So wouldn't that light energy (whatever the percentage) be considered as producing both light and heat ?

It first produced light, was absorbed and then produced heat.

And now I'm going to go torch a bowl of hash.....

 

[Black Sail]

Wouldn't the light result in a exothermic reaction where energy is released as heat ,, just kidding I know Jack ,, but very intresting

 

[Black Sail]

Full disclosure, I'm a busted up old fart who runs HID. Always will. But This thread caught my eye before my Morning bowl of hash and made me go hmmmmm..... hence my question.

So, here is why I asked it: when light energy is absorbed in my system some of it becomes heat. For example a black pot getting warmer, the floor getting warmer, etc.

So wouldn't that light energy (whatever the percentage) be considered as producing both light and heat ?

It first produced light, was absorbed and then produced heat.

And now I'm going to torch a bowl of hash.....

You make a very good point! As that light bounces around your growroom some fraction of the photons are absorbed into the walls and turn back into heat. The whiter/ more reflective your walls, the less this will happen. White paint will reflect about 93% of the photons so it's still wayyy worth it to have your watts converted into photons instead of heat. A lot of those photons will hit your leaves!

Chlorophyll and other pigments absorb & use the energy in the photon to bump one of their electrons up to a higher energy level. When the electron is at that higher energy level it can be used to make chemical reactions happen, like photosynthesis!

 

[HashMaster]

You make a very good point! As that light bounces around your growroom some fraction of the photons are absorbed into the walls and turn back into heat. The whiter/ more reflective your walls, the less this will happen. White paint will reflect about 93% of the photons so it's still wayyy worth it to have your watts converted into photons instead of heat. A lot of those photons will hit your leaves!

Chlorophyll and other pigments absorb & use the energy in the photon to bump one of their electrons up to a higher energy level. When the electron is at that higher energy level it can be used to make chemical reactions happen, like photosynthesis!

View attachment 973978

Ok... one bowl of hash down.... so....

So it was a good point, but it was wrong because the watt went to photon and the photon went to heat... correct ?

And as an aside.... I had always thought flat white absorbed less than reflective white... Is that incorrect ?

Bowl II break.....