Anthropogenic emission of greenhouse gases (GHGs) result in global climate destabilization, and the elements of GHGs associated with climate change are now well understood and a link to urban GHGs emissions has been well articulated. Compact city concept has been proposed for a while to response high energy consumption and GHGs emission in urban area. However, over compact might come up some problems, such as over-crowded of population, buildings, and cars which brining up other environmental issues. This study attempts to investigate potential negative impacts of urban compactness on energy consumption. The result shows that under a threshold of high density and mixed land use, it might come up energy saving outcome. However, it will become energy consumption while exceeding the threshold.