Figure 7: Thermal comfort condition for stabilised soil block walls with iron sheet( top) and thatched roofs( bottom).
Conclusion
This paper evaluated the effects of various construction methods on thermal comfort in low-income tropical housing in Uganda. Dynamic thermal simulations were conducted in EnergyPlus and the risk of thermal discomfort in naturally ventilated buildings was assessed for different walling and roofing methods. According to the results, an average internal operative temperature of 26 ° C would be an ideal comfort temperature in free-running buildings in Kampala. The maximum average internal temperature was also defined as 29 ° C. The comfort and maximum temperatures could however vary by up to 1.8 ° C depending on the running mean outdoor temperature.
According to the results of the simulations, roofing method / material is the most critical factor affecting thermal comfort conditions in low-rise free-running buildings in tropical climate of Kampala. The results reveal that, compared to iron sheet roof, thatched roof improved thermal comfort conditions by up to 15 times for criterion 1 of CIBSE TM52 guidelines. In other words, the risk of overheating( frequency of thermal discomfort), was reduced by up to 15 times when iron sheet roof was replaced with thatched roof. The two other criteria defined by CIBSE TM52 were also improved considerably for the thatched roof construction. Therefore, it could be argued that, when it comes to construction materials, improving thermal performance of the roof is key to improving thermal comfort in naturally ventilated buildings in tropical climates. Although important, walling materials were found to be less critical compared to roofing methods. The results of this study revealed that the thermal performance of different walling materials, with the exception of hollow concrete blocks, were almost identical. Hollow concrete block walls performed the worst in terms of providing thermal comfort. This was despite the fact that the thermal conductivity of hollow concrete blocks was considerably lower than solid concrete blocks, bricks and stabilised soil blocks. A possible reason for this is the much less thermal mass of hollow concrete blocks compared to the rest of the walling materials.
Improving thermal comfort in low-income tropical housing: the case of Uganda 621