Identify the differences of ac load requirement with respect to the floor number in high rise buildings

Abstract

Urban Heat Island phenomenon and heat column formation effects are directly affected by the outdoor temperature of the building. This leads to high on-coil temperature at the outdoor unit of the air conditioners (ACs). As a result, energy consumption by the AC system increases and Coefficient of Performance decreases and eventually provides low AC capacities than the rated amounts by the manufacturer. In reality and very often, building designers and shop keepers decide the required AC capacity for a given space referring the already tabulated cooling load capacity per unit area without performing any cooling load calculation or considering the other factors that would affect to the AC load. When it comes to high rise buildings, their approximations are often incorrect and obtaining the required thermal comfort from low capacity machineries is impossible. In order to prevent under-estimation of the required AC load, this study investigated the temperature increment of the outdoor conditions due to UHI and heat column formation by conducting few case studies and with the support of the Computational Fluid Dynamics simulations. It was revealed that in high-rise buildings surrounding temperature generally increases by 1.0 - 1.7oC for a 10-story building and the cooling load requirement of 10th floor in a high-rise building increases by 9-10% with respect to the ground floor.