Researchers Manuel Ruiz de Adana and José Luis Sánchez Jiménez, from the TEP 974 group – Research Group in Applied Thermal Engineering from the University of Córdoba (UCO) have carried out an experimental evaluation of outdoor thermal comfort in a Typical Cordoban tourist itinerary lasting three hours through the historic center of Córdoba. The research, as reported by the academic institution, was carried out after Córdoba recorded the highest temperatures in Andalusia in August last year and suffered up to 16 days of heat wave.
The results showed extremely high levels of thermal stress in all bioclimatic indices“which are those that allow us to estimate the thermal stress suffered by a person based on different environmental parameters”, as explained by Professor Manuel Ruiz from Adana.
Thus, on that walk through the Ribera area, the Roman Bridge, the Mosque-Cathedral, the Alcázar of the Christian Monarchs and the Calahorra area between 16:30 and 19:30 carried out on a normal summer day (July 6, 2023), a day with a heat wave (June 28) and a day with greater heat intensity, called a super heat wave (August 10), values were recorded of thermal stress very severe for the first and extreme for the second.
Taking into account that thermometers experience a more limited reality than humans, different bioclimatic indices to know the reality of the human body on those walks. Among them, the Universal Thermal Climate Index, or UTCI for its acronym in English (Universal Thermal Climate Index), which is the most complete because it “adjusts very well to the thermoregulatory mechanism of an average person,” according to the researcher.
/ Miguel Angel Salas
The researchers used a mobile measuring pole which simulated the person taking that tourist walk through the center of Cordoba, capable of registering a complete set of climatic variables. During the journey, environmental conditions such as radiant temperature, ambient temperature, air speed and relative humidity were measured at three different heights: ankles, abdomen and head.
These measurements yielded UTCI values of 43.9 degrees for the “normal” summer day, 45.6 degrees in the context of a heat wave, and 48.8 degrees during the super heat wave. As a reference, the thermal comfort limit on the UTCI scale is 26 degrees. Taking into account that a person must maintain a body temperature between 36 and 38 degrees, these data show that “For the average person there are serious associated risks and danger due to heat stroke in these conditions.“, Ruiz de Adana stressed. “We must remember that for every degree that the ambient temperature exceeds these thresholds, the risk of mortality attributable to high temperatures grows between 9.1% and 10.7%, that is, For every day that there is an episode of extreme heat, mortality increases, on average, by three deaths a day,” he detailed.
These results highlight the need to carry out interventions to improve the urban environment and promote a greater thermal comfort outdoors for those who live in the city through measures such as green infrastructure or shadows that also mitigate the heat island effect, that is, the increase in temperatures that occurs in the city with respect to the non-urban environment.
The UCO has recalled that in a context of climate change with increasing temperatures and increasingly frequent heat waves with results such as an increase in deaths due to heat – 13,320 deaths attributable to heat during the summer of 2023 – these types of studies are advancing in understanding the causes and effects of thermal stress. Along these lines, the research team proposes evaluate thermal stress on other routes in Córdoba and the effectiveness of different mitigation measures with the use of experimental measurements, external thermal stress simulation tools and the use of external thermal stress measurement robots.
