Literature Review of Energy and Water Use in Controlled Environment Horticulture and Potential Efficiency Opportunities

The purpose of this literature review is to present the current state of knowledge about the Controlled Environment Horticulture (CEH) industry and its energy and water use and to identify potential energy saving measures for consideration in future California Energy Code cycles. Gaps in knowledge and technological resources are also evaluated, as well as the feasibility and practicality of measure implementation in greenhouses and indoor farms used to grow vegetables, ornamentals, cannabis, and other crops.

Major Findings 
Key findings of this literature review include:

1. Best management practices are not well-established, especially for new crops and indoor farms without sunlight. Operational strategies vary across facilities, crop types, and targeted performance metrics.
2. There is a lack of energy use data collected from operating CEH facilities. Most reported energy use values are estimates based on computer models that rely on unverified operational assumptions or outmoded technologies. 
3. Energy codes and standards across California and the U.S. are varied and inconsistent.
4. Current HVAC and dehumidification equipment testing standards do not represent CEH operating conditions or use, while other technologies used in CEH facilities do not disclose performance metrics, limiting evaluation of product energy use effectiveness.
5. Energy saving opportunities exist for lighting, envelope, HVAC, irrigation, and controls. Some opportunities are well-established in the industry, while others require additional investigation before they are considered for inclusion in energy codes and standards.

Keyword Search:
Controlled Environment Horticulture, CEH, indoor agriculture, indoor plant environment, indoor farming, vertical farm, greenhouse, horticultural lighting, literature review, Title 24, cannabis, dehumidification, HVAC, irrigation