1 Laboratory of Energy Efficiency in Buildings, Federal University of Santa Catarina, Florianópolis, Brazil.
2 EAPLAB at CIRIAF - Interuniversity Research Center on Pollution and Environment, University of Perugia, Perugia, 06125, Italy.
3 Department of Engineering, University of Perugia, Perugia, PG, Italy.
4 Department of Building Services and Process Engineering, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Budapest, Hungary.
5 Construction Technologies Institute, National Research Council of Italy (ITC-CNR), San Giuliano Milanese, 20098, MI, Italy.
6 Controlled, Adaptive and Responsive Environments Laboratory (CARE), Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, USA.
7 Department of Mechanical and Aerospace Engineering, College of Engineering and Computer Science, University of Central Florida, Orlando, Florida, USA.
8 Department of Mechanical & Aerospace Engineering, Syracuse University, Syracuse, NY, USA.
9 Department of Civil, Environmental, and Architectural Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts, 01609, USA.
10 Healthy Living Spaces Lab, Institute for Occupational, Social and Environmental Medicine, Medical Faculty, RWTH Aachen University, Aachen, Germany.
11 Department of Building, Civil and Environmental Engineering, Gina Cody School of Engineering and Computer Science, Concordia University, Montreal, QC, Canada.
12 International Centre for Indoor Environment and Energy, Department of Environmental and Resource Engineering, Technical University of Denmark, Kgs, Lyngby, Denmark.
13 Department of Mechatronics, Optics and Engineering Informatics, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Budapest, Hungary.
14 Healthy Living Spaces Lab, Institute for Occupational, Social and Environmental Medicine, Medical Faculty, RWTH Aachen University, Aachen, Germany. mschweiker@ukaachen.de.
15 Chair of Healthy Living Spaces, Faculty of Architecture, RWTH Aachen University, Aachen, Germany. mschweiker@ukaachen.de.

Understanding cross-modal environmental perception is essential for improving occupant well-being and human-centric building design. This paper presents an open-access, multi-site database developed under the IEA-EBC Annex 79 project to test the Hue-Heat Hypothesis (HHH), which hypothesizes that light hue may influence thermal perceptions. The database comprises 543 experimental rounds conducted in eight laboratories across six countries and diverse climate zones, following a shared, rigorously designed protocol. During summer and winter campaigns, participants were exposed to controlled thermal environments and counterbalanced lighting conditions (neutral, reddish, bluish). The database includes detailed metadata on environmental variables, physiological measurements (i.e., heart rate and skin temperature), and self-reported perceptual responses. It also provides standardized technical documentation for each test room, including the detailed experimental protocol and translated survey instruments. All materials are available on the Open Science Framework under the "Multi-site Hue-Heat-Hypothesis Testing" repository. This resource supports research into multi-domain human comfort, enabling analysis of cross-modal and combined effects on human perception and physiological reactions.