Eliminating greenhouse heat stress with transparent radiative cooling film

Greenhouse cultivation is becoming increasingly important to feed the growing population. Temperature needs to be regulated properly for greenhouse production. Herein, a 115-μm-thick transparent radiative cooling (T-RC) film is specially designed as a covering material for greenhouses to reduce heat stress without sacrificing photosynthesis. With high emissivity in atmospheric window, high transmittance in photosynthetically active radiation (PAR), and high reflectivity in near-infrared radiation (NIR), T-RC film is demonstrated to lower the indoor temperature of a greenhouse by 18.6°C without ventilation compared with polyolefin (PO) film. The productivity of three varieties (Chinese cabbage, pakchoi, and cherry radish) was accelerated by 23.4%, 17.3%, and 21.7%, respectively, within 19 days after seeding. Moreover, a modeling study shows that this film can save cooling water by 64.8%. This study paves the way for highly productive greenhouses in hot regions with high productivity and high crop quality, along with both energy savings and water savings.