TL :: DR
-gpw is not accurate
-gpw does not allow direct comparison of growths
- g per kWatt hour is more accurate and allows direct comparisons of growth
- g per kWatt hour is a correct estimation of the amount of electricity (hence cost in bills) going in each growth
Fellow growers, you know better than me that, as gardeners (or hunters or fishermans or anyone which deals with "nature"), we like to compare our growths with each other. Either to improve ourselves or just for the sake of competition and ego stroking
.
The main and most immediate "method" that is used to measure buds productivity is usually the "gram per watts" (gpw): pretty much dividing the amount of dried buds produced by the amout of watts of lighting used in the growth. a quick example: 1000g of buds produced in a system with 500W or lights would be 2gpw (1000/500).
this method however lacks one critical information: time. this method does not account for how long plants have been grown under said amount of Watts of lights. this critical flaw of this method not only makes growths not comparable to each other (as different growth times alter the final size of the plants), but also does not accurately calculate the amount of electricity put (and paid for) in the growth.
A simple example (note, numbers are just pulled from my ass): grower A grows in a small tent, with 150W of LED lights per plant. Because of space limitations, he only vegs for 3 weeks then flowers. on average one of its plants yields 100 grams of dried buds, making a gpw of 0.66. on the other hand, grower B has a full growth room, and can afford to veg his plants for 3 months then flower. at the end, each of his plants make on average 300g of dried buds, for a gpw of 2. using only gpw, it would look that grower B would be a much better grower, but you can see that this method does not account for the fact that grower B spent more than twice the amount of electricity to produce his buds.
The alternative: the only accurate way to compare different growths productivity is to use the "grams per kiloWatt hour" (gpkWh). This method factors in the amount of time (and hence electricity) that went into each growth.
how do you calculate it? is very simple. you measure the amount of watts of lights of your system, and you multiply it for the amount of time the lights were on to calculate the total amount of kilowatt hour that went into your growth. formula: grams of dried buds/(kilowatts of light system * hours of lights on per day* number of days of growth)
taking the example above, Grower A vegged for 3 weeks with 150W of lights, which make 0.15kW * 24 hours (the amount of hours the lights were on during veg) * 21 (number of days of veg), for a total of 75kW hour for veg. for flowering would be 0.15kW * 12 (only 12 hours of lights on per day) *56 (number of days in 8 weeks of flower), for a total of 100kW hour used in flower. that makes a complete 175kW hour used for the whole growth, ie 0.85 gpkWh.
For Grower B the 3 months of veg would use 0.15*24*90 (approximate days of 3 months) = 324kW hour used. assuming equal flowering time, the flowering of grower B would also take 100kW hour, as explained above. a total of 424 kW hour used over the whole growth, which make a gpkWh of only 0.35.
now you see that using this method of calculating productivity grower B is actually much less efficient in transforming electricity into buds.
additionally, since electricity bills are usually calculated on the Kwatt hour used, this method allows to precisely calculate how much money in electricity bills went into your growth.
so my advice is to use this method when calculating your growth productivity, is better, is more informative and allows for direct comparisons. grams per watts pretty much mean nothing by itself.
-gpw is not accurate
-gpw does not allow direct comparison of growths
- g per kWatt hour is more accurate and allows direct comparisons of growth
- g per kWatt hour is a correct estimation of the amount of electricity (hence cost in bills) going in each growth
Fellow growers, you know better than me that, as gardeners (or hunters or fishermans or anyone which deals with "nature"), we like to compare our growths with each other. Either to improve ourselves or just for the sake of competition and ego stroking
.The main and most immediate "method" that is used to measure buds productivity is usually the "gram per watts" (gpw): pretty much dividing the amount of dried buds produced by the amout of watts of lighting used in the growth. a quick example: 1000g of buds produced in a system with 500W or lights would be 2gpw (1000/500).
this method however lacks one critical information: time. this method does not account for how long plants have been grown under said amount of Watts of lights. this critical flaw of this method not only makes growths not comparable to each other (as different growth times alter the final size of the plants), but also does not accurately calculate the amount of electricity put (and paid for) in the growth.
A simple example (note, numbers are just pulled from my ass): grower A grows in a small tent, with 150W of LED lights per plant. Because of space limitations, he only vegs for 3 weeks then flowers. on average one of its plants yields 100 grams of dried buds, making a gpw of 0.66. on the other hand, grower B has a full growth room, and can afford to veg his plants for 3 months then flower. at the end, each of his plants make on average 300g of dried buds, for a gpw of 2. using only gpw, it would look that grower B would be a much better grower, but you can see that this method does not account for the fact that grower B spent more than twice the amount of electricity to produce his buds.
The alternative: the only accurate way to compare different growths productivity is to use the "grams per kiloWatt hour" (gpkWh). This method factors in the amount of time (and hence electricity) that went into each growth.
how do you calculate it? is very simple. you measure the amount of watts of lights of your system, and you multiply it for the amount of time the lights were on to calculate the total amount of kilowatt hour that went into your growth. formula: grams of dried buds/(kilowatts of light system * hours of lights on per day* number of days of growth)
taking the example above, Grower A vegged for 3 weeks with 150W of lights, which make 0.15kW * 24 hours (the amount of hours the lights were on during veg) * 21 (number of days of veg), for a total of 75kW hour for veg. for flowering would be 0.15kW * 12 (only 12 hours of lights on per day) *56 (number of days in 8 weeks of flower), for a total of 100kW hour used in flower. that makes a complete 175kW hour used for the whole growth, ie 0.85 gpkWh.
For Grower B the 3 months of veg would use 0.15*24*90 (approximate days of 3 months) = 324kW hour used. assuming equal flowering time, the flowering of grower B would also take 100kW hour, as explained above. a total of 424 kW hour used over the whole growth, which make a gpkWh of only 0.35.
now you see that using this method of calculating productivity grower B is actually much less efficient in transforming electricity into buds.
additionally, since electricity bills are usually calculated on the Kwatt hour used, this method allows to precisely calculate how much money in electricity bills went into your growth.
so my advice is to use this method when calculating your growth productivity, is better, is more informative and allows for direct comparisons. grams per watts pretty much mean nothing by itself.
