What is NExT? A new conceptual model for comfort, satisfaction, health, and well-being in buildings

Buildings are designed to respond to functional and regulatory needs, providing comfortable conditions to occupants, offering satisfactory environmental settings, minimising health risks, and enhancing individual and collective quality of life. Although there are synergies between these goals, no comprehensive framework has yet been formulated to characterize human comfort, satisfaction, health, and well-being in buildings as distinct, yet highly interrelated, constructs. Founded on a critical consolidation of interdisciplinary literature, and of the key performance indicators for the most common factors of environmental quality featured in standards and codes, this paper proposes a new conceptual model that can sustain the whole of human experiences in buildings, addressing the variety of their uses and occupancy. Embracing the notion that environmental stimuli may synergistically or antagonistically combine, at various spatio-temporal resolutions, to influence building- and occupant -related outcomes, the proposed model, NExT, suggests that there could be significant discrepancies between the design and operation strategies aimed at energy efficiency, the conditions demanded for comfortable task performance, what contributes to satisfaction with the indoor environment, and what is required for building users to be healthy and feel well over time. There is a need to fundamentally challenge our understanding of the criteria that are used for designing, measuring, and benchmarking the performance of buildings, encompassing the perspective of the occupant. This implies going beyond designing buildings to ensure neutral acceptance of conditions and prevention of harmful exposures while, instead, driving from interdisciplinary studies to integrate the dimensions of human experience in building research, policies, and practice.