He is regarded as one of the foremost designers and noted authority on ecologically-responsive architecture and planning. His latest book is, Ecodesign: Manual for Ecological Design. He has pioneered the passive low-energy design of tall buildings, which he calls the 'bioclimatic skyscraper'. He has received numerous awards for his work and designs that include the Aga Khan Award for Architecture, RAIA International Award, Prinz Claus Award, UIA August Perret Award. His key built works include the Menara Mesiniaga tower (Malaysia), the National Library (Singapore) Great Ormond Street Hospital Extension (UK). He is an Honorary Fellow of the American Institute of Architects, past Chairman of ARCASIA and has served on the Royal Institute of Architects Council. He is a principal of the UK architect and planning firm, Llewelyn Davies Yeang and its sister company, Hamzah & Yeang (Malaysia).