This chapter investigates the green building related policy tools, aiming to gain experience and find opportunities to bring affordability issues into the current green building development. The chapter selects Hong Kong and Singapore as case studies for the investigation. Singapore and Hong Kong are the leaders in Asian green building revolution. The investigation is based on the work of Pearce et al. (2007) who categorized green building policies into four aspects: policy options which is a formal execution, applied as an official procedure to mandate or encourage green building action; programs which support green building practice with monetary or information; implementation which offers guidance and technical support on the project level when developers or designers would like to achieve certain goals; and evaluation which serves to measure the actual performance of green building. The lessons learnt from the green building development related policies include clear roadmap, market-driven and top-down approach, government project taking the lead, incentive design, approaches towards different stakeholders, building performance information disclosure. This chapter argues that the green building policy greatly helps move forward the green building development regardless of the incremental capital cost and to make them affordable and doable in terms of development and construction. However, there are few concerns about affordable and buyable in the market. Policy instruments should cover both building green and buying green.