Heating and ventilation efficiencies of a solar chimney integrated system in a low-energy office building

Abstract

Mechanical air conditioning systems have a significant share of energy consumption in the building sector. Passive solar systems, such as solar chimneys, can reduce building energy demand by supplying space heating, cooling, and ventilation, significantly decreasing greenhouse gas emissions. Therefore, this study aimed to evaluate the heating and ventilation efficiencies of a solar chimney integrated system, including a roof solar chimney coupled with an air channel, for a two-story office building in Tehran, Iran. The studied system's conditions are switchable from heating to cooling by changing the opening positions. Computational Fluid Dynamics was employed to numerically investigate the heating and ventilation efficiencies of the proposed solar system. The results confirmed that the system could be utilized for pre-heating purposes during working hours but that the building should be ventilated only for 35% of this time with an air change rate of 0.8 during the year's coldest month. The arrangement could provide thermal and ventilation comfort for the occupied space only at solar intensity and ambient temperature higher than 550 W/m2 and 10 °C, respectively. In addition, the solar system could reduce 32% of the annual heating demand (918 kWh), which is equal to a reduction of 1865 kg of CO2 emissions during working hours.