The incorporation of environmental and energy considerations into the building design will become the main stream of the construction industry. This paper intended to demonstrate the life-cycle assessment method employed in the analysis of energy consumptions and environmental impacts during the life time of the school buildings in Taiwan. There are two popular types of school buildings in Taiwan nowadays. One is steel-based construction (hereafter referred to SC). The other is reinforced concrete construction (hereafter referred to RC). Two selected buildings located at Taichung County have been analyzed in the study. Five stages were identified in the whole life of school buildings including material production, erection, occupation, demolition, and disposal/recycling scenario. A 50-year service time was assumed for both buildings. The results show that the most energy consumption occurs in the occupation stage for both selected school buildings. They contribute 95.8% and 87.2% of the total energy consumption in its service time for the SC and RC buildings, respectively. However, the construction processes may influence the energy consumption significantly. It also concluded that both selected buildings consumed lots of energy during the first 30 years, and then energy consumptions of the selected school buildings was leveled off. The inventory data was simulated in an LCA model and the environmental impacts for each stage were indicated as numerical scores based on the Eco-indicator 99.