A new publication in “Building and Environment” introduces the Interior Accumulated Thermal Overload (IATO) model, which estimates heat-related mortality based on simulated indoor temperatures and considers the prevalence of active cooling systems across regions.
oPEN Lab partner, the University of the Basque Country (EHU), published a new scientific paper titled “Interior accumulated thermal overload (IATO): A novel indoor temperature-based metric for assessing heat-related mortality through building simulations”, in the journal “Building and Environment”. It presents and validates the new model (IATO) that estimates heat-related mortality using simulated indoor temperatures and building characteristics, rather than outdoor heat alone. It helps to better capture real human exposure and supports climate adaptation and public health planning.
The study shows that the IATO methodology can reliably estimate heat-related mortality using indoor temperatures and building characteristics, demonstrating strong agreement with national mortality data, highlighting the critical role of HVAC and building design, and offering a promising tool for assessing overheating risks and retrofit impacts, while noting the need for further validation, broader data, and integration of building, temporal, and socioeconomic factors to strengthen its nationwide applicability.
As a real-world test case, the study applied the IATO model to a residential building in Pamplona, one of oPEN Labs Living Labs, simulating different retrofit measures, such as added insulation, a ventilated façade and shading, to demonstrate how building upgrades can reduce indoor overheating and heat-related excess mortality.
Publication details:
Moreno-Pestaña, P. & Diarce, G. (2026). Interior accumulated thermal overload (IATO): A novel indoor temperature-based metric for assessing heat-related mortality through building simulations. Building and Environment, Volume 289. https://doi.org/10.1016/j.buildenv.2025.114094
Learn more about the oPEN Lab living lab in Pamplona here.
