Quality of the indoor environment has become an important parameter to account for in new and existing buildings due to the increasing number of people spending most of their time indoors. Generally, the design and evaluation of indoor environments in buildings rely on appropriate guidelines and recommendations. National and international IEQ standards specify indoor environmental conditions considered acceptable to most occupants. This publication reviews and critically compares the requirements for indoor thermal environment and ventilation for acceptable air quality across international standards such as ISO, EN and ASHRAE and national standards of China, India, Singapore, and Australia.
The critical analysis of IEQ standards demonstrates that regional differences and diversity factors due to factors such as climate, building typology, demographics, and culture might not be appropriately addressed both in national and international standards, limiting the feasibility of universal indoor environmental criteria. In addition to that, most of the standards provide recommendations for various categories of thermal comfort and air quality by focusing on the perception of IEQ by occupants rather than productivity and wellness as quantitative criteria. The review shows that thermal comfort and air quality parameters are treated separately and without an integrated assessment of various environmental quality-related dimensions. Therefore, there is a need for a method to combine various indoor environmental factors into a combined indicator.