A low-cost modular monitoring system for spatial lighting and occupant-centered comfort assessment: Development and validation

Indoor lighting quality influences occupant comfort, task performance, and energy use. However, its evaluation in real buildings is often constrained by the cost, complexity, and limited spatial coverage of laboratory-grade instrumentation. This study presents ecoDAQ, a low-cost and modular monitoring system designed for multi-domain assessment in real-world environments, with a focus on lighting and thermal comfort. The platform integrates (i) a light toolkit for spatially resolved illuminance and basic spectral measurements, and (ii) an occupant-centric toolkit designed to collect subjective user feedback while simultaneously recording local environmental parameters in the immediate vicinity of the occupant for thermal comfort assessment. A CCT-augmented multilinear calibration model is introduced to improve illuminance estimation under varying light-source spectra. Laboratory calibration and field validation against reference instruments demonstrated good agreement, with illuminance uniformity errors below 2.5%. The occupant-centric toolkit showed comparable performance in thermal comfort assessment, with limited deviations in PMV and PPD indices. The system was further demonstrated in an office case study using two contrasting lighting configurations. Results show that ecoDAQ can reliably capture spatial variations in lighting and support the interpretation of occupant perception under stable environmental conditions. With a total hardware cost below €350, ecoDAQ provides a validated solution for occupant-centered field studies, post-occupancy evaluation, and long-term indoor environmental monitoring.