As the second largest GHG emitter in the world, the building sector needs to play an active role in reducing GHG emissions. Particular attention should be directed to existing buildings, not only because of the amount of emissions caused by inefficient buildings but also due to the existence of a variety of sustainable refurbishment solutions for different levels and stages of building refurbishment. The emission reduction performance of different sustainable refurbishment options, however, varies enormously as a result of different building design conditions. Cooling, for example, is a much more important consideration than heating in warmer climates. For high-rise multi-story existing buildings, due to the complexity of the occupant mix and their emission reduction goals, more attention should be paid to reducing the energy consumption of common areas and increasing the energy performance of the building envelope. This paper provides a comprehensive literature review of the nature and assessment of existing sustainable refurbishment options for residential buildings in sub-tropical high-density cities such as Hong Kong. The paper will also help policy and decision-makers delineate a set of sustainable refurbishment solutions that are suitable for multi-story buildings to maximize the opportunity for reducing their emissions.