How Tmrt Affects PET Assessment in Outdoor Environments: A Comparative Study

Abstract

Many studies have explored outdoor thermal comfort during the last several years, ever since it has been strongly related to human health and well-being. The physiological equivalent temperature (PET) is one of the most commonly used thermal comfort indexes. It has been approved and applied within different urban spaces and climates. This study is a comparative research that explored the importance of using mean radiant temperature (Tmrt) in PET assessment by employing two different methods. The first method was used to calculate PET based on three measured variables including relative humidity, wind velocity, and air temperature. RayMan software was utilized to perform the calculations. The second method was used to calculate PET by combining Envi-met and RayMan. Envi-met allowed four sets of calibrated data, including the data of air temperature (Ta), wind velocity (Wv), relative humidity (RH), and mean radiant temperature (Tmrt). RayMan software used the calibrated results to calculate PET. These methods were explored in outdoor environments at Annaba, Algeria, characterized by a Mediterranean climate. The results showed significant differences in PET values, especially through the warmest times of the day. The first method highlighted very high PET values, where 40 ≤PET<51 at noon. At the same time, using Tmrt gave precise PET values (30≤PET ≤32). Based on these findings, we can confirm the importance of considering Tmrt in PET calculation, which allows one to identify the accurate comfort range.
 Keywords: Algeria, Mean Radiant Temperature (Tmrt), mediterranean climate, Physiological Equivalent Temperature (PET), thermal comfort