This study demonstrated that, under commercial strawberry cultivation with a relatively low heating demand (setpoint air temperature of 7 °C), the ZEG-type greenhouse achieved substantial reductions in both primary energy consumption and CO2 emissions during the monitoring period (approximately 58% and 68%, respectively) compared with the reference greenhouse operated under the same environmental control strategy. Furthermore, additional reductions in primary energy consumption and CO2 emissions were obtained through on-site PV generation by offsetting grid electricity consumption, as illustrated in Fig. 7. These results provide fieldbased evidence of the decarbonisation potential of the ZEG concept, integrating low-carbon technologies such as groundwater-source heat pumps, double thermal curtains, and on-site PV generation into fossil fuel–dependent greenhouses commonly used in Japan.