ATLAS: A Performance-Based Index for Integrated Evaluation and Benchmarking of Indoor Environmental Quality

Indoor environmental quality (IEQ) is a central determinant of occupant health, comfort, and well-being, and is closely intertwined with building energy use and operational performance. Yet, prevailing IEQ evaluation methods rely primarily on threshold-based criteria that inadequately capture the multidimensional and interdependent nature of IEQ and the variability in occupant perceptions. This study presents the ATLAS Index (Air quality, Thermal comfort, Lighting, and Acoustics Scale), a novel performance-based framework for integrated and continuous IEQ evaluation, developed for residential environments but readily adaptable to other indoor spaces. ATLAS integrates multiple parameters across four IEQ domains using a logarithmic aggregation method that prioritizes the lowest-performing domain, minimizes artifacts associated with rigid threshold cut-offs, and enables flexible domain weighting. Parameter selection and scoring criteria are grounded in internationally recognized guidelines and standards including WHO guidelines, ASHRAE standards, and EN standards, adapted to residential environments where relevant. Occupant perceptions were integrated by dynamically reweighting IEQ domains using Bayesian updating based on periodic surveys. The ATLAS index was demonstrated with 1.5 years of continuous IEQ measurements from 10 occupied apartments in Valencia, Spain. Results show that acoustic conditions frequently constrained overall IEQ scores, and that correlations between objective IEQ scores and self-reported satisfaction were weak, underscoring the complexity of interpreting residential IEQ based solely on physical measurements. An open-source web-based visualization tool is provided to facilitate practical deployment and benchmarking. The ATLAS index provides a flexible and scalable framework for next-generation IEQ assessment, adaptable to evolving emerging sensing technologies and diverse building contexts.