Prolly more like photons produced/power consumption=heat or just look up how effiecient the light is its usually posted somewhere
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Calculating Heat Load from Lighting Fixtures
Whenever doing heat-load calculations, we must always count 100% of the fixture wattage-any fixtureâs wattage-as heat, regardless of efficiencies at the source. In any enclosed space, virtually all of the light produced by a lighting fixture is eventually absorbed by surrounding materials (walls, ceilings, etc.). When light gets absorbed by these materials, photons are converted into heat.
New lighting technologies, such as LEDs, allow luminaires to produce light more efficiently, or with higher efficacy than incandescent lamps. This means that we get more lumens per watt; however, heat per watt is constant. What matters is that fewer watts are used to produce comparable brightness, not that these fixtures somehow produce less heat for the wattage that they consume.
1 watt of electricity used by a luminaire = 3.412 BTUs per hour
i am pretty sure i was right the first time actually. heat = watts x 3.412 always
efficacy doesnât matter
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The spectrum is slightly different for each diode. Here is the spectrum anaylsis of the LM302c diode and the LM561c diode temperature and CRI are the same and ran with the same current and voltage (these two diode are in the same family and bin the same way as well)
Its always a good idea to find out which diode the LED strip/cob is using and look at the manufactures data sheets to find the spectrum analysis
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I llive learning something new
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Efficacy matters because you need less Watts for the results.
yes thatâs what i said the first time. you use less watts to achieve the same lumens/PAR, but efficacy doesnât change heat generated per watt. always 3.412 BTUs per hour per watt
Yes @legalcanada and @Ttystikk you are very correct that
1 J/s (Joule per second) = 1 W (Watt)
1 W (Watt) = 3.414 BTU/hr
LED uses less watts to achieve same equivalent wattage HPS output from a lumen standard. Therefore the LED unit will have less BTU/hr than the HPS unit, but that is heat generated. Not how it dissipates throughout the enclosed space.
Temperature over Time is relative to the environment. Its all depends on Thermal Resistance (heatsinks & air), Thermal Conductivity, Ambient Temperature and Humidity, Air flow, Enclosed space
You can find all of those variables and then make a calculation that will give you accurate Temperature over Time
But it all boils down to thisâŠ
You could still have a bad ass LED system running equivalent to an HPS system for less watts(less heat generated), but if your ventilation sucks. then it donât matter because if you canât properly vent off the excess heat then the LED system will heat itself to the fail point (usually over 85Âșc). Think of a boiler, if it didnât have a thermostat to turn it off, BOOM! It would heat itself until it critically fails.
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Where is this from? Is it made in the context of a horticultural environment? From a laws of thermodynamics perspective, this is certainly true, energy is never destroyed, only transferred. In a sealed white cube, any light or source of electrical resistance consuming say 100w per hour will eventually produce the same total amount of âheatâ, all else being equal.
But eventually weâll all be dead. Thermodynamics accepts very long horizons in its proofs.
In a grow room environment we are producing vegetation. Vegetation produced by carbon, hydrogen, oxygen, minerals and light energy. Growers go to great lengths to direct as much of that light energy, photons, at the plant canopy and not allow it to be absorbed by the walls.
Plants do not simply absorb light energy like a rock or piece of sheetrock does, inertly. Plants dynamically convert light energy to sugars, proteins, cellulose, etc. The energy used by plants to grow is not released as heat, it is bound up in the plantâs tissues and fluids. This energy is not released as heat again until the vegetation is burned. The total amount of heat produced by burning all the vegetation produced in the space = the amount of light energy NOT released as heat during the growing period.
Again, conservation of energy principle, your quoted writerâs original point, but in a horticultural context.
Or think of it another way, using the analogy of plant leaves as solar energy panels. If you lined that empty cube with photoelectric panels, and hung a 100w light in the middle, a certain amount of heat AND electricity would be produced. Based on the conservation of energy principle, no energy is created, only transferred. So if all light energy in the box eventually becomes heat, where is the electricity coming from? Itâs coming from the light energy that wasnât converted to heat.
The greater the proportion of watts that can be converted to photons (efficiency) the greater the amount of energy available to be absorbed and converted to plant material. And less energy is emitted as waste heat in the grow space in begin with - remember most of the heat we are talking about was never emitted as âlightâ in a visual or photosynthetic sense, it was emitted as infrared energy, i.e. heat, through electrical resistance. Not from light being absorbed into walls and converting to heat.
Anyone who has grown with both a traditional HID and a modern, efficient LED light (not cheap blurple) in the same space knows this simply by observation. Many folks who convert to LED from HID immediately go from the problem of too much to too little heat in their spaces. They sell their AC units and buy heat mats.
But the pure efficiency argument actually begs the question of how mid-power LED strips are truly better at managing the heat vs. lumens issue. LED strips distribute the lumens, and the waste heat, evenly across the canopy, eliminating the hotspots and variations in intensity that plague single-light HID lit spaces. Even if they emitted exactly the same amount of photons and waste heat per watt, an LED strip system will produce more consistently usable photonic energy at the canopy than a single lamp HID system. More usable photonic energy means less watts needed to create the same or better product.
-b420
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Great explanation! I knew there was something missing form that equation. It seems obvious hearing it now.
The amount of energy absorbed by the plants and concerted into products of photosynthesis is on the order of 1-2% of the total.
Much more is absorbed and then shed through transpiration.
Do yourself a favour and donât buy another blurple, grab 150/200 watts of Solstrips from @Baudelaire, I use COBs and they are fantastic but these Solstrips are a little more efficient, cheaper, easier to put together and make for a better looking and cleaner build.
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Not doubting you, but do you have a cite for this statement? Is it made in the context of outdoor daylight? This would seem to vary depending on the DLI of the environment and the minimum and maximum DLI requirements of the plants within it.
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another very simple thing about LEDâs is the fact that all the light is aimed downward at the canopy. HPS & MH bulbs have a PAR number but that is from a spherical testing chamber. In the real world, 50% of the light must first travel upward, bounce off a reflector, and then back down again, losing intensity all the way.
Iâm liking LED more and more as time goes on. My 600w Gavita HPS, actually 660 true watts, was replaced by a 320w lamp, no bullshit, the yield is at least as high with the Hortiled.
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Do some Google searches, the data is out there.
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photosynthetic efficiency for solar energy is around 1-3% but about half the suns energy is outside the usable range. iâd guess using light thatâs all within the range would double it to 2-6%? this report seems to indicate they were able to increase productivity by ~4% using LEDs, but was for algae not a plant crop
i think safest bet if building new room or adding AC is calculate every watt at 3.412 BTU per hour of heat
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Probably still the safest bet, oversize the A.C. a bit is better than not having enough.
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A little bit late update here 
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We have seen this video in all of your other threads, is it really necessary to post it on every other thread to do with lights as wellâŠ
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Hi
How did you get on with build and during your kit??