Dr. Mui graduated from The Hong Kong Polytechnic University with a First Class Honours in BEng (Hons) Building Services Engineering in 1996; he obtained a PhD in the same field in 2002. After receiving industrial work experience in building services design and project management in an international electrical and mechanical consulting company, he joined the Department of Building Services Engineering at the University in 2000 and was promoted to Associate Professor in 2010.

Dr. Mui has been managing numerous research projects and his students study building and environmental engineering covering areas of indoor air quality, energy efficient building technology and energy engineering. He is internationally known for his works in indoor air quality sampling, guidelines and bioaerosols indoor environments. Dr. Mui and his students have published more than 100 refereed journals and archival papers and more than 100 conference papers and technical reports on IAQ assessment, bioaerosols depositions, performance of the new demand control ventilation system, performance of deodorizer systems, adaptive comfort temperature model for air-conditioned buildings and certain advanced areas of building environmental performance respectively. A number of his articles were the most-frequently read articles ranked by SAGE journals in Jan 2010 in the field of Indoor and Built Environment. Besides, Dr. Mui’s papers were recognized amongst the most cited articles published in Elsevier's Building and Environment between 2005 and 2008. He was conferred the Emerald Literati Network Awards for Excellence in 2011.

He is an Honourable Advisor for Hong Kong Indoor Air Quality Society (HKIAQS) and a founding member and Co-chairman of the Technical Working Group (TWG) of ASHRAE Hong Kong Chapter. He also serves as Affiliate Faculty Member of School of Nursing, The Hong Kong Polytechnic University for collaborating research in ventilation control of infection in health care facilities and community settings. He also serves as member of international advisory boards and scientific committees of major international conferences in the field of indoor air quality, provided invited speeches, and undertook numerous high-level IAQ consultancies and Reviewing Measurement Protocols for Existing Indoor Air Quality Parameters under the Indoor Air Quality Certification Scheme (Client: HKEPD). He holds 2 patents in the area of Indoor Environmental Quality (IEQ) logger and ICU extraction unit for hospital use.

He directs the research of IAQ sampling protocol, guidelines and bioaerosols at the HKPU, and has published widely in this field. His main research interests are in (i) indoor air quality impacts on health, performance and perceptions; (ii) ventilation, energy and thermal comfort; and (iii) indoor exposures to airborne infectious agents. He has strong collaboration internationally and with local agencies across his research interest areas, and has been greatly involved in the development of local IAQ and ventilation standards in Hong Kong also. He has recently developed and refined a database for the IAQ in densely built urban environments (Hong Kong). In 2014, his work has been highly commended and he was appointed to investigate the feasibility of developing Indoor Air Quality (IAQ) index in Hong Kong (Central Policy Unit, HKSAR).