Significant changes to lighting for plant growth in the 2021 International Energy Conservation Code

An addition to Section C405.4 (Lighting for Plant Growth) of the 2021 International Energy Conservation Code (IECC) states that a provision regulating lighting for plant growth and maintenance has been added to ensure indoor agriculture operations are energy efficient.

Previous editions of the IECC have not addressed lighting requirements for indoor agriculture plant growth and maintenance, yet indoor growing operations are becoming increasingly common for both traditional farming crops and marijuana. Indoor agriculture energy usage is projected to grow substantially over the next several years due in part to the legalization of medicinal and recreational marijuana growth and sales. The Northwest Power and Conservation Council projects that indoor marijuana growing operations alone will add as much as 300 average megawatts by 2030. This is equivalent to 1.5 percent of total regional electricity demand. Other studies have shown that lighting for indoor agriculture has accounted for 45 percent of the electric load growth in some states.

This new provision and associated standard—ANSI/ASABE S640— require 95 percent of the lighting used for plant growth or maintenance to meet an efficiency metric of 1.6 μmol/J (micromoles per joule). The metric was developed in collaboration with the American Society of Agricultural and Biological Engineers specifically for lighting used for plant growth. It measures the number of photons emitted from the fixture per joule of energy consumed. This minimum photon efficiency is consistent with the Conservation Practice Standard Energy Efficient Lighting System Code 670 issued by the U.S. Department of Agriculture in January 2020.

This provision is applicable to both IECC compliance paths.

Read the full significant change.

The 2021 Significant Changes guides are available for the International Building, Fire, Residential, Energy Conservation, Plumbing, Mechanical and Fuel Gas Codes. This valuable series can help any code user save time by zeroing in on the most critical changes in the 2021 International Codes. The Code Council’s technical experts provide summaries, analysis and graphics for these changes making them clear and easy to understand. Each edition provides a comprehensive analysis of significant changes since the 2018 edition, offering key insights into its contents and implications. Each change analysis features the affected code sections and identifies the change with strikethroughs and underlines to show modifications to the existing language. Each change is accompanied by a quick summary, detailed illustrations, and a discussion of its significance, which brings the technical jargon of the code to life in a real-world setting.

Significant Changes to the International Energy Conservation Code, 2021 Edition, is available in the ICC Store or through Digital Codes Premium.