Purpose The amount of energy consumption of buildings has obtained international concern so the concept of zero energy building becomes a target for building designers. There are various definitions and evaluation methods for efficient buildings. However, detailed research about the critical parameters that have a major effect through the operational time to reduce the energy consumption is not emphasized as this paper represents. The main aim of this study is to identify the effect of applicable interventions on energy consumption parameters with their sensitivity to each other to reach zero energy building. Relatedly, the cost of energy reduction is also determined. Design/methodology/approach Energy consumption parameters were defined as area lightings, space heating, space cooling, ventilation fans, pumps, auxiliary equipment and related miscellaneous equipment. The effect of each applied intervention on energy consumption was classified as high, medium, low, very low, no effect and negative effect by utilizing a sensitivity analysis. The base case's energy model is created by utilizing energy performance software such as e-Quest. Accordingly, energy performance improvement scenarios are developed by applying interventions such as lamp replacements, sensors, heat pumps and photovoltaic panels' integration. Furthermore, sensitivity analyses of each intervention were developed for consumed energy and its cost. Findings Results indicated the electric consumption is more effective than gas consumption on prime energy and energy cost. Solar systems decline prime energy by 78.53%, lighting systems by 13.47% and heat pump by 5.48% in this building; therefore, integrating mentioned strategies could rise the improvement rate to 100%, in other words, zero amount of energy is using from the grid that means saving $ 5,750.39 in one year. Research limitations/implications The study can be applied to similar buildings. It is worthwhile to investigate suggested methods in diverse buildings with different functions and climates in future works. Practical implications This study aims to investigate of energy consumption of an educational building in the Mediterranean climate to convert an existing building into a zero energy building by saving energy and renewable sources. Subsequent purposes are analyzing the effect of each strategy on energy consumption and cost. Originality/value The novelty of this study is filling gaps in sensitivity analysis of energy consumption parameters by not only identifying their effect on overall energy consumption but also identifying their effect on each other. Some interventions may have a positive effect on overall consumption while having a negative effect on each other. Identifying this critical effect in detail not only further improves the energy performance, but also may affect the decision-making of the interventions.