Investigation of thermal comfort efficacy of solar chimneys under different climates and operation time periods

Abstract

A Solar Chimney (SC) is a passive system harnessing solar energy to ventilate inner spaces and improve occupants’ thermal comfort. The purpose of this study is to determine the time periods of a year most suitable for the use of a SC in terms of thermal comfort under the different climates of Bandar-Abbas (hot and humid), Yazd (hot and arid), Paris (mild and humid) and Toronto (cold and humid). To this aim, a thermosyphonic model – validated against published experimental data – was employed for running dynamic thermal simulations of a residential building using the EnergyPlus software.The optimal time periods of operation of the SC, driven by the values of the Predicted Mean Vote (PMV) between −0.7 and +0.7 and Predicted Percentage of Dissatisfied (PPD) below 15%, are found to be November and January to April in Bandar-Abbas (2265 h), while for the city of Yazd it comprises the months of April and May together with September and October (2145 h). As for Paris and Toronto, the period spans from June to August, for a total of 1065 and 1620 h respectively.Correlation coefficients disclosing the impact of the increased air mass flow rate revealed a positive impact everywhere during nighttime in terms of indoor air temperatures (from 0.02 in Bandar-Abbas to 0.77 in Yazd). On the other hand, the impact on indoor relative humidity is always negatively correlated, with a peak of −0.73 in Yazd. Year-long comfort conditions are finally displayed in psychometric charts against ASHRAE 55 Standard boundaries.