Reducing Energy Demands in Greenhouse Farming: The Potential of Passive Solar Greenhouses in the U.S.

Abstract

Controlled environment agriculture has significantly enhanced agricultural productivity around the world. However, greenhouse farming operations in Western countries remain highly energy-intensive, with heating accounting for the majority of energy use. In the Netherlands, heating accounts for around 74% of total energy input. Passive solar greenhouses (PSGs) offer an energy-efficient alternative by utilizing direct sunlight as the sole heat source. Their design incorporates thermal mass, enabling high thermal gain and substantially reducing energy consumption. While PSGs are widely implemented in Asia, their adoption at a commercial scale in the United States has been limited. This study investigates the feasibility of implementing PSGs across diverse U.S. climate zones by evaluating their thermal performance and energy-saving potential. Four locations representing different climate zones were selected for case studies. A passive solar greenhouse model was used for energy and lighting simulations, testing various combinations of wall assemblies, glazing materials, shading, ventilation, and night insulation strategies. Results indicate that PSGs increase the duration of ideal internal temperatures in all four locations. They are particularly effective in cold and marine climates, where they significantly raise interior temperatures without supplemental heating. Their performance is less effective in hot climates. Given that heating accounts for the largest portion of energy use in conventional greenhouses, PSGs show strong potential for cold regions. As more than half of the U.S. falls within cold and marine zones, PSGs offer a promising solution for year-round vegetable production with minimal energy input.