Energy efficiency in medicinal cannabis cultivation and processing requires stable environmental conditions due to the specific requirements throughout the growing and processing stages, ensuring consistency in the composition of the different cannabinoids. This allows the final product to be considered a medicinal product with specific properties.
In most cases, energy consumption represents one of the most significant costs in medicinal cannabis production and can ultimately determine whether an industrial operation is profitable. An energy-efficient facility design can directly improve operational profitability while reducing the carbon footprint, adding further value to these plant-based products.
Facility Design Considerations
Most measures aimed at optimising environmental control and stability, as well as improving energy efficiency, require a higher initial investment. Since this investment is decided upon and made well before the operating licence is obtained, assessing a cost whose return may take several years can make the decision-making process more complex.
On the one hand, high energy costs encourage us to design facilities around efficiency and energy savings. On the other, uncertainty surrounding the medicinal cannabis market — including volumes and prices — together with the complexity of the product and its production process, calls for a cautious approach.
There is no single “standard” solution for optimal facility design. The right solution depends on multiple factors and must therefore be tailored to each project:
- Location: environmental conditions, including temperature, humidity and hours of daylight.
- Size of the operation: batch size and potential future expansion.
- Final product: whether intended for direct consumption or extraction.
For all these reasons, this article identifies the different factors that should be analysed when implementing technical solutions designed to improve the facility’s energy efficiency. The results of this analysis should then be incorporated into the profitability assessment for each individual project, taking into account the potential improvements identified.
Energy Efficiency in Medicinal Cannabis Cultivation
Energy efficiency in medicinal cannabis cultivation must be optimised. If there is one point on which the industry agrees, it is that any improvement in the stability and reliability of cultivation conditions leads to better yields and higher product quality, ultimately increasing profitability.
Location
Location is one of the most important considerations due to its significant economic impact. Ideally, the site should be located in an area with a climate suited to the requirements of the crop and sufficient hours of daylight. Access to good-quality water and a reliable electricity supply must also be ensured, as these factors directly influence facility design, capital investment and operating costs.
Lighting
Cultivation lighting can be provided by sunlight, artificial lighting or a combination of both. Using natural light can reduce energy consumption, but the type of building envelope must be carefully considered.
Film-based enclosures provide the highest level of natural light transmission but offer lower airtightness and insulation in cold regions or during colder nights. Blackout screens may therefore be required to improve thermal insulation.
Other materials, such as polycarbonate or glass, improve thermal insulation but reduce solar transmission and increase the initial investment.
Locations close to the equator provide the best natural lighting conditions throughout the year. However, as we move further away from the equator, maintaining a stable light level requires supplementary lighting or even systems capable of providing the entire required light output. In these cases, dimmable LED lighting should be used to provide only the additional light required to complement natural sunlight and minimise energy consumption.
In facilities with opaque building envelopes, such as sandwich panels, lighting is entirely artificial and remains consistent regardless of the season. Where the facility is connected to the electricity grid, one way of controlling consumption and reducing costs is to operate the lighting at night. Where no grid connection is available, photovoltaic panels and battery storage should be considered, allowing lighting to operate during the day and extending the photoperiod to 12 hours or more for vegetative growth and mother plants.
External Insulation
External insulation helps reduce the energy required to regulate and control cultivation temperature and humidity. However, insulating roofs and walls can reduce natural light transmission and consequently increase the energy required for artificial lighting. Each project must therefore be assessed individually to find the right balance.
Except in locations with exceptionally favourable climates, floor insulation is generally a worthwhile investment. A concrete slab installed over an insulation layer and vapour barrier — which also helps preserve the quality and durability of the finishes — provides both insulation and thermal inertia during cold nights. This is particularly beneficial because maintaining a slightly higher temperature around the lower part of the plant, especially the root zone, is desirable.
Indoor Environmental Conditions
Maintaining appropriate temperature and humidity conditions during the day, at night and throughout the year is another major source of energy consumption. Some locations and technical solutions may need to be ruled out during the project assessment due to excessive humidity or unsuitable thermal conditions.
The main challenge is managing the humidity generated by the plants. During the daytime phase, plants transpire almost all the water absorbed through their roots. The most economical way of reducing indoor humidity is to replace greenhouse air with drier outdoor air. Depending on how dry the outdoor air is, there may even be scope for adiabatic cooling, making this one of the most energy-efficient solutions available.
However, as outdoor environmental conditions cannot be guaranteed, dehumidification and cooling systems must also be considered to manage the moisture generated by the plants, as well as internal heat loads from lighting and external thermal loads. Energy efficiency will depend heavily on an effective control system capable of reducing operating costs whenever outdoor conditions are favourable.
At night, particularly in colder regions, it is important to:
- Reduce air changes to the minimum required, while ensuring sufficient oxygen supply.
- Increase thermal insulation using blackout screens, air-gap curtains or similar systems.
- Heat the areas around the roots, even if the upper areas of the greenhouse are allowed to cool.
Carbon Dioxide (CO₂)
To increase crop yields, it is common practice to raise CO₂ concentrations above ambient levels during the day. However, this practice involves both financial costs and a carbon footprint that must be assessed to ensure profitability.
Operating with higher CO₂ concentrations requires a precise balance between nutrient supply and light levels. Without this balance, the expected increase in yield will not be achieved, while costs may rise and final product quality may even decline.
Increasing CO₂ concentrations while introducing high volumes of fresh air is generally uneconomical. For this reason, CO₂ enrichment is primarily recommended for indoor cultivation facilities or airtight greenhouses.
In large-scale facilities where combustion processes are used to generate energy or hot water, combustion gases could potentially be recovered to increase CO₂ concentrations through appropriate filtration, storage and cooling systems.
Efficient Heating and Cooling Generation
Climate control, dehumidification and drying processes all require efficient heating and cooling generation. We recommend considering centralised production systems which, despite requiring a higher initial investment, offer several advantages:
- Larger equipment generally provides better control — including condensation control and inverter technology — together with higher-performance compressors and therefore greater energy efficiency.
- These systems can generate heating and cooling simultaneously, improving overall efficiency, particularly because cultivation and processing areas often require heating and cooling at the same time.
- The total quantity of refrigerant gases is reduced, maintenance can be managed more effectively, and industrial equipment is designed for continuous operation.
For heating and cooling distribution, hot- and chilled-water circuits are recommended. Variable-flow distribution systems are particularly suitable for these facilities because heating and cooling requirements can vary considerably between day and night and across different seasons.
Energy Efficiency in GMP Processing Rooms
Energy-efficiency solutions for GMP processing rooms are well established within HVAC systems. However, there are several specific considerations when applying them to medicinal cannabis processing.
Air Handling Unit Zoning
It is important to distinguish between different areas according to their environmental requirements and operating schedules. Humidity-controlled environments are only necessary in rooms where the product is already dry and exposed to the surrounding environment, such as dry trimming, curing and packaging areas.
In areas where the material remains wet, such as defoliation and wet trimming, lower temperatures are required. It can therefore be beneficial to provide these areas with an independent air handling system.
Within the same facility, most rooms will operate for one or two shifts and, until the facility reaches full production capacity, some rooms may remain unoccupied. Other areas, such as drying tunnels, may operate 24 hours a day.
It is therefore important for air handling systems to allow individual zones to be isolated or switched off, or to operate at reduced temperature settings and airflow rates when full capacity is not required.
Efficient Water Management
The quality and quantity of available water are key considerations when selecting a site, although they may not always be the determining factor. Several aspects should be considered:
- Irrigation will normally be hydroponic, preferably using controlled and channelled drainage systems so that drainage water can potentially be reused for less sensitive crops, landscaping or other applications where higher conductivity is acceptable.
- Rainwater and condensate generated by dehumidification systems can be recovered and redirected to emergency irrigation water storage tanks. These tanks are already present in most facilities, meaning that the additional investment required for water recovery is relatively low while providing a valuable source of high-quality water.
- Reverse osmosis reject water can be reused for non-GMP cleaning, toilet flushing and other suitable applications.
Conclusions
The technical solutions required to improve energy efficiency already exist and are well understood. The main challenge in medicinal cannabis production lies in evaluating their impact due to the limited availability of data on how these measures affect product yield and quality.
Based on our experience, we believe that the starting point should be a robust facility design that ensures product quality. Once operations have reached a stable level, continuous monitoring and analysis by experienced, specialised personnel should be used to progressively achieve energy-efficiency and profitability objectives while maintaining compliance with GMP requirements.