Circular Cannabis Systems: Tracking and Minimizing Waste and Emissions Impacts

Published on: 
Cannabis Science and Technology, November/December 2021, Volume 4, Issue 9

Columns | <b>The Cultivation Classroom</b>

Learn how to bring efficiency concepts together to create circular cannabis systems.

Cultivation operations use resources such as energy and water and also generate waste products like wastewater, biomass waste, and other solid waste such as growing supplies and packaging materials. Growers can benefit from learning about circular processes that recapture waste streams to improve operational efficiency and reduce impacts on surrounding communities and sensitive environments. Specialized waste benchmarks help businesses track emissions of cultivation facilities to quantify the costs and benefits of implementing circular best practices. Compare year-over-year performance and contrast key performance indicators against industry averages to value and prioritize strategies. Minimize environmental impacts by controlling horticultural lighting to improve yields, recapturing, treating, and reusing drained irrigation water, and minimizing crop loss through effective integrated pest management (IPM). In this final “Cultivation Classroom” column of 2021, bring efficiency concepts together to create circular cannabis systems.

Emissions associated with cannabis operations include greenhouse gas emissions from production processes, wastewater, and solid waste. For growers in some regions such as Illinois and Colorado, there may be regulations requiring the management of certain types of emissions. It is crucial for cannabis businesses to stay competitive in changing markets by understanding the opportunities for circularity in their facilities. Circular economy metrics benchmark the emissions generated by facilities to measure progress towards regenerative practices and reward validated sustainability performance.

Resource Innovation Institute (RII) gathers Technical Advisory Council key stakeholders and subject matter experts in the Emissions Working Group (1) to standardize methodology for quantifying emissions associated with indoor agriculture, determine data the market needs to understand the emissions impacts and benefits of controlled environment agriculture, and motivate the industry to utilize low-carbon approaches across a range of cultivation methods and geographies to increase resilience and reduce vulnerability.

Avoiding Greenhouse Gas Energy Emissions

The greenhouse gas (GHG) emissions impacts of cannabis production include emissions from cultivation and post-harvest supply chain processes. In cultivation and processing, cannabis demands energy and creates associated emissions impacts. Globally, nearly 80% of all GHG emissions come from the production and consumption of energy. Growers of all kinds use systems that need energy in order to increase yields.

Outdoor farms use energy for pumping for cultivation, environmental control, and on-farm transportation and hauling. Irrigation systems require electricity for pumping water. Equipment for heating and farm vehicles require fuel. Greenhouse and indoor facilities can have higher energy demands than field farms. Indoor vertical farms use high-intensity sole-source horticultural lighting systems to optimize growth and high-capacity HVAC systems to maintain climate and airflow. Greenhouses use electricity for supplemental lighting, and in colder climates where greenhouses seek to supply year-round harvest, greenhouses also use fuel for heating.

Energy used for cannabis cultivation has different emissions impacts depending on fuel choice and source energy for regional electric grids (2). Facilities can minimize GHG emissions by using energy-efficient lighting and HVAC equipment, producing on-site renewable energy, and minimizing use of fossil fuels.


Closing the Water Loop

Climate change, resource constraints, and environmental disasters impact cannabis businesses along with human and ecosystem health. During peak drought cycles approximately one-quarter of the US experiences extreme or exceptional drought (4). A future of rising costs and tightening access to water due to prolonged and historic droughts make water efficiency an increasingly urgent priority.

In field farming, water that is not retained by plants is evaporated back into the surrounding environment or drains as runoff, carrying soil and fertilizer into groundwater, rivers, and lakes. Water recirculation systems used by greenhouses and indoor cultivation facilities design out waste and keep a constrained resource in use. Both kinds of facilities present opportunities to recapture, treat, and reuse irrigation water (5). Indoor farming can also recycle condensate captured from HVAC and dehumidification systems. Regenerative practices are phenomenal opportunities for sustainable water practices; recirculating indoor farms can use 90–95% less water than field farms (6). In some regions, cannabis operations must implement wastewater treatment plans to recapture condensate and treat and reuse drained irrigation water.

Recycling Waste

Solid waste emissions from cannabis facilities include biomass, cultivation supplies, and packaging waste. Used substrate and root balls from grow rooms and branches, stems, and leaves from trimming are examples of cannabis biomass waste. In some regions, cannabis biomass cannot be composted, or is required to be mixed with other kinds of waste. Supplies to support optimal plant growth and development such as trellis netting can be challenging to reuse and impossible to recycle. Many growers and consumers are also concerned about packaging waste. Regulations in some areas can make recycling packaging materials difficult, and consumers are often left responsible for finding sustainable options.

Benchmarking Cannabis Emissions

Accounting for the emissions impacts of cannabis is possible with specialized benchmarking tools like Resource Innovation Institute’s PowerScore (7) that can calculate key performance indicators (KPIs) for resource efficiency and productivity for outdoor, greenhouse, and indoor cultivation operations. PowerScore has KPIs for energy-associated greenhouse gas emissions, water, and solid waste. RII’s Emissions Working Group peer reviews changes to the PowerScore platform related to emissions and prioritizes new KPIs to measure both emissions impacts and benefits (see Figure 1).

Cannabis businesses can be recognized for excellence with environmental reporting and certification programs. Certification programs help address the need to measure progress toward circularity as climate change, resource constraints, and environmental disasters impact human and ecosystem health. Benchmarking tools such as PowerScore can be used as inputs to the certification process to prove circularity of resources like energy and water. Certification programs and benchmarking tools like PowerScore evaluate the resource efficiency and productivity of controlled-environment agriculture (CEA) facilities while rewarding regenerative practices like keeping materials in use, conserving water, and reducing energy consumption.

Creating a Circular Cannabis Economy

Greenhouse and indoor cultivation approaches offer pathways to a circular cannabis economy and are increasingly important strategies as extreme weather events increase in frequency, resources like water are further constrained, and demand for cannabis continues to increase globally. Energy use and associated greenhouse gas emissions of cannabis production should be measured with benchmarking tools to understand ecosystem impacts so certification programs reward circular practices in the cannabis industry.

Download RII’s latest free “Best Practices Guide on Automation & Controls for Cannabis Cultivation” (8). Access RII’s guides on LED Lighting, HVAC, and Controls for Cannabis Cultivation at Check out RII’s past “Cultivation Classroom” columns on their author page (9-13).


  10. G. Schimelpfenig, Cannabis Science and Technology 4(1), 16-18 (2021).
  11. G. Schimelpfenig, Cannabis Science and Technology 4(2), 14-16, 23 (2021).
  12. G. Schimelpfenig and T. Robinson, Cannabis Science and Technology 4(4), 13-18 (2021).
  13. G. Schimelpfenig, J. Porter, and C. Burg, Cannabis Science and Technology 4(6), 18-25 (2021).


GRETCHEN SCHIMELPFENIG, PE, As Technical & Operations Director, Gretchen manages the PowerScore resource benchmarking platform, facilitates RII’s Technical Advisory Council Working Groups, and manages RII’s continuing education program for producers, efficiency programs, and design and construction communities. She works with members and subject matter experts to publish technical guidance for the production of plants in controlled environments, develops and delivers curriculum, and supports PowerScore users with resource benchmarking analysis and reporting compliance. She authors RII’s Best Practices Guides for controlled environment agriculture.

Gretchen is a licensed Civil Professional Engineer (Construction) in California and Vermont. She also has a specialty in analyzing the interactive effects between HVAC and lighting systems and commissioning controls systems. Gretchen grows vine crops, cannabis, and herbs in her veggie garden, greenhouse, and basement in her Vermont farmhouse and is constantly using her HVAC and lighting knowledge to optimize her grow environment.

How to Cite this Article

G. Schimelpfenig, Cannabis Science and Technology 4(9), 22-24 (2021).