Population ageing and building stock ageing are usually tackled as two separate subjects, and each has already received much attention. However, the Hong Kong community at large is less aware that the combined impact of population ageing and building ageing, i.e. “Double Ageing”, is a much more complex issue to address. If not tackled properly and in a timely manner, “Double Ageing” as a socio-economic issue will impact on the sustainable development of Hong Kong, significantly affecting the liveability and resilience of the city.