The increasingly heavier dependence on air conditioning in office buildings is one of the key causes of climate change. This dependence increases our vulnerability to climate change, and reduces the ability to avoid the effects of global warming. The impact of air conditioning on electricity demand is a very significant issue in office buildings. The potentials of sustainable architecture through effective energy-saving design, and energy conservation such as efficient natural ventilation design. In order to encourage sustainable architecture the adoptions of energy-saving design strategies, the environmental design standards, the energy conservation standard and criteria, aiming to reduce the energy consumption in public buildings. Natural ventilation is an energy conservation method which may help reduce buildings energy consumption, improve the thermal comfort condition and maintain a healthy indoor environment. This paper applied physical measurement and questionnaire to determine the effect of sustainable architecture and the potential of energy conservation of naturally ventilation. The Analysis of Variance (ANOVA) test conducted at 95% confidence level showed that there was significant statistical difference between the sustainable architecture and the potential of energy conservation of naturally ventilation thus: F=65.555; p=.000. The result shows that natural ventilation can provide an acceptable indoor environmental condition without air conditioning. Recommendations were made for energy saving strategies to be applied both in the design phase of a building and when renovating existing buildings to achieve energy conservation.