One of those "a friend of mine" stories

[mshields]

But this one really is about "a friend of mine". So anyway, that friend is going to the electrical work for a Marijuana growing facility and he wanted me to check his calculations. I have the connected load. And of course as much of it is heat related, I'm taking that at 100%. But what I'm wondering is what, as a practical basis, a good diversity estimate. Or, sliced another way, does anyone have experience with what these facilities run in terms of watts per square feet. You know, if you too have a "friend" in that industry.

PS: Why am I so coy. It's perfectly legal and besides it really is for a friend

 

[GoldDigger]

The main way there could be diversity in the lighting would be if the grower had multiple separate growing areas which were blocked off from outside light and operated them each on a different 24 hour cycle. The down time for harvesting and moving in new plants would be minimal AFAIK.

 

[electrofelon]

I have done parts of/upgrades in several such facilities and one from the ground up. The one from the ground up I did all the design. The bloom rooms are on 12 hour cycles so they should stagger those to reduce electrical infrastructure costs. The vegetative stage runs 18-6 though so practically you have to count that full time. I just got the grower to tell me how many lights they want to run at one time, and it was more than half but less than all.

Lights were 1000W HPS (1050 to-1100 watts actual draw) on a 5x5 grid. The air conditioning was engineered so I just used the MCA. Just for rough numbers, this is a 100x300 building and the service I installed was 277/480 1200 amps and will do the whole facility to NEC load calcs.

 

[gadfly56]

I have done parts of/upgrades in several such facilities and one from the ground up. The one from the ground up I did all the design. The bloom rooms are on 12 hour cycles so they should stagger those to reduce electrical infrastructure costs. The vegetative stage runs 18-6 though so practically you have to count that full time. I just got the grower to tell me how many lights they want to run at one time, and it was more than half but less than all.

Lights were 1000W HPS (1050 to-1100 watts actual draw) on a 5x5 grid. The air conditioning was engineered so I just used the MCA. Just for rough numbers, this is a 100x300 building and the service I installed was 277/480 1200 amps and will do the whole facility to NEC load calcs.

So, if my math is correct, that's about 33 watts/sqft which is about 3 times what my house is per square foot for the connected service. How close are they running to their installed capacity?

 

[electrofelon]

So, if my math is correct, that's about 33 watts/sqft which is about 3 times what my house is per square foot for the connected service. How close are they running to their installed capacity?

The place is currently only half built out. Out of that half, one out of the two bloom rooms is not set up either. If fully operational , considering NEC fudge, I bet the place would see about 700 amps max. 428 lights max on at one time is what they told me. So assuming that 700 amp max guess, that is only 19 watts/sq ft. But that includes processing and drying space, etc.....take just a bloom room 75X50, 104 lights, AC MCA is about 100 @ 480, actual draw probably around 65 = 44 watts/sqft, but at 50% duty cycle.

 

[ggunn]

The main way there could be diversity in the lighting would be if the grower had multiple separate growing areas which were blocked off from outside light and operated them each on a different 24 hour cycle. The down time for harvesting and moving in new plants would be minimal AFAIK.

This is especially important if the POCO tariff includes demand charges.

 

[JFletcher]

But this one really is about "a friend of mine". So anyway, that friend is going to the electrical work for a Marijuana growing facility and he wanted me to check his calculations. I have the connected load. And of course as much of it is heat related, I'm taking that at 100%. But what I'm wondering is what, as a practical basis, a good diversity estimate. Or, sliced another way, does anyone have experience with what these facilities run in terms of watts per square feet. You know, if you too have a "friend" in that industry.

PS: Why am I so coy. It's perfectly legal and besides it really is for a friend

From what I've read, Watts per sq ft of grow space would be nearly 100 at 12on/12off, tho I see electrofelon's real world numbers much lower than that. AC loading could vary greatly depending on geography. Other spaces/sq ft of the facility will have relatively light loads compared to the grow/bloom rooms and AC demand.

 

[lakecitieselectric]

From what I've read, Watts per sq ft of grow space would be nearly 100 at 12on/12off, tho I see electrofelon's real world numbers much lower than that. AC loading could vary greatly depending on geography. Other spaces/sq ft of the facility will have relatively light loads compared to the grow/bloom rooms and AC demand.

[why not use LED]

 

[gadfly56]

[why not use LED]

As I understand it, not the right spectrum, although I do recall reading something that someone was tackling the issue.

 

[GoldDigger]

[why not use LED]

Wrong spectrum.

 

[electrofelon]

Wrong spectrum.

There are some grow LEDs that are supposed to be as good or better than HPS...Not sure if thats BS or not - saw it on a glossy sales brochure with all sorts of tables and graphs . One place I did some work in had some LED's and I recall them not being happy with them. IT would seem that LED's would be more efficient, but if you look at the lumens per watt, I dont think it is better than HPS believe it or not. In my limited experience in that industry, it seems HPS is still king.

 

[JFletcher]

[why not use LED

afaik, mj is a lumens whore. it wants lumens, lots of lumens, and lumens only. mushrooms care about spectrum, mj want the Sun to be about 10' overhead vs ~93M miles away haha. that's still HPS