Abstract The greenhouse areas in Iran have expanded rapidly and the greenhouse holders have shown a great tendency to cultivation of those crops that used to be cultivated in open fields. Although, greenhouses are intensive in terms of yield and whole year production, they are considered being one of the major contributors to greenhouse gases (GHG) emissions in the agricultural sector. In the present study strawberry cultivation in greenhouses (GH) and open fields (OF) was selected as a representative of those crops which can be grown in both systems. Initial data were randomly collected from 70 OFs and 33 GHs in province of Gilan, Iran. Energy consumption and GHG emission of two different strawberry production systems were compared. Moreover, energy use efficiency of GH producers due to more energy consumption was studied, then degrees of technical efficiency (TE), pure technical efficiency (PTE) and scale efficiency (SE) were determined using data envelopment analysis (DEA). Additionally, the amount of energy inputs wasted in inefficient greenhouses was assessed and energy saving was computed. Furthermore, the effect of energy optimization on GHG emission was investigated and the total amount of GHG emission was calculated. The total average of energy input and output was estimated at 35,092.4 MJ ha−1 and 10,405.9 MJ ha−1 for OF production and, similarly, 1,356,932.8 MJ ha−1 and 137,772.4 MJ ha−1 for GH strawberry production. Total GHG emission was calculated as 803.4 kg CO2eq ha−1 and 35083.5 kg CO2eq ha−1 for OF and GH production, respectively. Based on the evaluations 20.2% (273,902.8 MJ ha−1) of overall energy sources can be saved if the performance of inefficient farmers is enhanced. Optimizing energy in the greenhouse production can result in a significant reduction in total GHG emission and the present emission of GHG can be reduced to the value of 29309.1 kg CO2eq ha−1.