While I believe there will always be a market for high-quality indoor flower product, ultimately the energy costs of production will be too high for cultivators trying to stay competitive in the commercial marketplace on indoor alone. There is no other plant in the world being cultivated on a massive scale where most of the production takes place indoors.
As @thatgatesguy mentioned, cannabis that is skillfully grown in a high-tech modern greenhouse can compete with indoor when it comes to quality and potency. While these structures can have a high start-up cost, building out an entirely new indoor facility of the same size will cost far more. Even retrofitting existing warehouse space to properly cultivate cannabis may end up costing more than a new greenhouse in some cases. I have seen indoor retrofit operations where environmental control was more of a concept than an achievable goal and the results can be disastrous and ultimately expensive.
In the webinar that @Dan_Monk shared, Nick Earls broke down the energy usage of indoor operations and found that lighting, cooling and dehumidification comprised 89% of energy consumption. There are many ways to reduce those energy costs in a greenhouse. Evaporative cooling systems cost 50% less than traditional A/C systems. Dehumidifiers are often unnecessary and even when required they will not be utilized as often as is typical in a sealed indoor setting.
Then there are the obvious savings on lighting. As demonstrated in the webinar, the ability to use the sun as a primary light-source for just a few hours per day resulted in a 4.5x reduction in energy usage.
Many growers are resistant to a greenhouse operation due to concerns over heating the structure in the winter. While that is a valid concern, in most cases the savings on energy consumption will outweigh the added costs of heating.
Zachary Carr, one of our Commercial Greenhouse Designers, has provided a tool to help growers estimate annual energy costs and make that assessment:
Estimated fuel use - Fuel use (FU) = C x U x A x D where
C = coefficient based on heat value of fuel and efficiency of heating unit
U = “U” value of glazing or building wall
A = surface area of building where heat is lost
D = degree days for period when greenhouse is heated (inside night temperature minus 5°f to 6°F for solar gain). Degree days are available at www.degreedays.net. A site nearest the greenhouse should be selected. An average of three years data is best. Degree days may from year to year vary by 20% above or below the average.
After calculating fuel use we factor in energy savings from use of screens (light deprivation or shade systems) with a 25% safety factor.
For electric (heating, venting & cooling only) we assume 3.5kWh/ft2 coefficient.
The number below represents a 10,080 square foot Series 2000 greenhouse facility using 93% efficient heaters & a temperature setpoint of 70F – all one room with 14’ sidewalls – comprised of (3) 35’ wide x 96’ long spans gutter connected using 2017 weather station data from Pueblo Memorial Airport in CO.
Based on my calculations we would conservatively estimate that 10,296 gallons of propane & 35,280 kWh would be consumed annually.
10,296 X $2.00 = $20,592.00
35,280 X $0.20 = $7,056.00
Compare this with Nick Earls’ conservative estimate of 175kWh/ft2 for annual indoor energy consumption. Powering an indoor facility of the same size could cost over $350,000 a year.
175 X 10,080 = 176,4000kWh
176,4000 X $0.20 = $352,800.00