Indoor environmental quality (IEQ) refers to the condition of a building’s internal environment that is related to the occupants’ health, comfort, and wellbeing. The assessment and improvement of IEQ in buildings are based on either subjective or objective assessment or the use of both measures, and in recent times, have been attracting attention due to its role in contributing to green building and sustainable environment. This study is aimed at evaluating and analysing the validity of the IEQ parameter traits as assessed using subjective and objective measures. The convergent and discriminant validity of the measured parameter traits were tested by analysing a multitrait–multimethod (MTMM) matrix using confirmatory factor analysis (CFA). The results indicated that there is no convergent validity in the IEQ parameter traits as assessed using subjective and objective methods. However, discriminant validity of the measured parameter traits was adequately supported. This clearly shows that as much as IEQ parameter traits measured through objective physical measurement and subjective occupant survey define the same concept, they cannot be taken to represent a single and same unit of measurement.