Which definition best matches Indoor Environment Quality (IEQ)?

• A. A plan for evaluating energy efficiency and occupant comfort
• B. The log of commissioning issues
• C. The infiltration rate of a building
• D. A perceived indoor experience of the building indoor environment that includes aspects of design, analysis, and operation of energy efficient, healthy, and comfortable buildings.

Answer: (D)

Indoor Environment Quality is the perceived indoor experience of the building, including how design, analysis, and operation shape energy-efficient, healthy, and comfortable environments. This best captures IEQ because it centers on occupant experience and acknowledges the combination of factors that influence that experience—air quality, thermal comfort, lighting, acoustics, moisture—while tying them to health and energy efficiency. The other options describe a plan, a log, or a single metric rather than the holistic, occupant-centered concept that IEQ represents.