A Comparison Between Predicted and Actual Thermal Sensation in Non-air-conditioned Residential Buildings in a Tropical Climate: A Case Study

Abstract

AbstractMaintaining optimal indoor thermal comfort has identified to be a necessity for residential buildings in tropical climates, especially, when there are no countermeasures available such as air-conditioning. Predicted mean vote (PMV) and actual mean vote (AMV) are widely used to determine indoor thermal comfort of buildings in different climatic conditions. PMV predicts the thermal sensation of the occupants considering ambient physical parameters: indoor air temperature, mean radiant temperature, relative humidity, and wind velocity, whereas AMV determines actual thermal sensation of the occupants through standard thermal comfort surveys defined by ANSI/ASHRAE Standard 55. Out of these, predicted mean vote (PMV) is the most popular model in predicting indoor thermal comfort, however, is known to contradict the actual thermal sensation (AMV) of occupants in different intensities for various climatic conditions. Therefore, this study has been carried out to compare the results of predicted and actual values of thermal sensation for a tropical climate using six non-air-conditioned residential buildings located in Gampaha, Sri Lanka. The buildings were selected within an area of 1 km radius to neutralize the effects of microclimatic differences. The data collection was carried out covering four different tropical climatic seasons from the month of July to December 2020 including field measurements and questionnaires (N = 2200). Regression analysis and Pearson correlation tests were performed to assess the strength of the relationship between predicted and actual thermal sensations. The results revealed that there is a significant mean difference between AMV and PMV for all four seasons, as + 1.399, + 1.139, + 0.934, and + 0.855, respectively. Furthermore, predicted neutral temperatures recorded for each season were 25.89 °C, 26.39 °C, 26.15 °C, and 26.43 °C, whereas actual neutral temperature recorded for these seasons were 29.58 °C, 28.59 °C, 28.00 °C, and 27.76 °C, respectively. Hence, the results suggest that for a tropical climate, PMV model underpredicts the actual neutral temperature of the occupants.KeywordsIndoor thermal comfortResidential buildingsPredicted mean vote (PMV)Actual mean vote (AMV)