Green building (GB) policies have been implemented to promote GB and address climate change. Most of the existing literature have studied the costs and benefits of developing GB, without considerations of GB policies’ impacts. This paper aims to study the costs and benefits of implementing GB policy from the developers’ perspective. It takes the Gross Floor Area (GFA) Concession, which is a popular policy and has been implemented in the US, Singapore and Hong Kong, as an example, to compare its implementation in three regions and analyze how it affects developers’ costs and benefits. Findings show that Hong Kong has a relatively lower threshold to acquire GFA concession for developers and it is the right time to adjust the GFA concession incentive to reflect the market transformation and further encourage developers to go for higher levels of GB.