Human Thermal Comfort and Its Analysis by Computational Fluid Dynamics for Naturally Ventilated Residential Buildings of Jimma Town, South West Ethiopia

Abstract

Human thermal comfort level investigation was made in naturally ventilated residential house of warm temperate oceanic climate of Ethiopia – Jimma town. Thermal variables (air temperature, wind speed and relative humidity) of purposely selected brick wall and wooden wall residential buildings were measured. Analysis was made using SPSS (version 20) statistical software and compared with thermal comfort standard (ASHRAE standard 55-2004). Computational fluid dynamics (CFD) with its fluent software was used to visualize the temperature distribution and air speed pattern in the residential buildings. The thermal comfort in the buildings was found outside the limits specified in the set standard. The result shows that residential houses in Jimma Town generate thermal discomfort to their residents due to their improper designing and construction. The CFD simulation suggests the use of adaptive mechanisms such as opening windows, changing cloths, and internal window insulation to improve indoor thermal comfort level of residential buildings in Jimma town. Setting indoor thermal comfort by adaptive mechanism is a means to conserve final energy as it is environmentally friendly and generates no toxic substances. Thus, it is recommended that all stakeholders including architects, engineers and environmentalists should work collaboratively in designing residential houses, with better natural ventilation are thermally comfortable to their residents.

Keywords: Air movement; Air temperature; Computational Fluid Dynamics (CFD); Residential buildings; Thermal comfort