KS was appointed as the Secretary for the Environment, Hong Kong Special Administrative Region Government, between 2012 and 2022. During his ten-year tenure as the “environment minister”, KS initiated a series of sustainability policy blueprints, from climate actions, energy saving, clean air, popularisation of electric vehicles, waste management and circular economy, to biodiversity, leading Hong Kong towards carbon neutrality before 2050. In mid-2024, KS published the book Hong Kong Stories in the Journey towards Carbon Neutrality (邁向碳中和 香港人和事).

KS is also Distinguished Department of Architecture Fellow and Adjunct Professor in the Department of Politics and Public Administration at The University of Hong Kong, and Honorary Professor at Hong Kong Chu Hai College. Since the late 2022, KS has started to serve as Chairman of Wu Zhi Qiao (Bridge to China) Charitable Foundation, leading rural revitalisation projects in both the Mainland and Hong Kong and integrating youth development and low-carbon transformation.

KS as an architect has developed expertise on sustainable architecture since the early 1990s. He contributed to various award-winning projects and research in sustainable built environment, from pioneering high-density public housing estate Verbena Heights in the early 1990s to CIC-Zero Carbon Park in the early 2010s. KS was the Founder Chairman of the Environment and Sustainable Development Building Council (2009-2010) and Vice Chairman of the Hong Kong Green Building Council (2012).