Indoor Relative Humidity Characteristics in Selected Low-Income Buildings in the Different Ecological Belts of Rivers State: Implication for Thermal Comfort Condition

Abstract

This study examined the indoor relative humidity (RH) characteristics of selected low-income 
residential buildings across three ecological belts (Derived Savannah, Coastal Vegetation, and 
Rain Forest) of Rivers State, Nigeria. The thrust of the study was to examine RH observed and 
implications for thermal comfort in low-income buildings in the area. The study deployed the 
experimental research design to establish the variation in Relative humidity characteristics in 
the area. RH data were collected from 15 three-bedroom bungalows (five per ecological belt) 
for a period of six months (January to June 2024). The Acurite 00613 data loggers with ±1% 
precision was used. Data were logged at four climatological hours daily (00:00, 06:00, 12:00, 
and 18:00). ANOVA was applied to determine the spatial variations in RH across the 
ecological belts. Results revealed that RH was high across all belts, and exceeded ASHRAE's 
recommended 30–60% comfort range. Peak RH was recorded in June in the Derived Savannah 
(81.4% ± 1.11), followed by Coastal Vegetation (78.3% ± 1.17) and Rain Forest (76.9% ± 
1.03). The lowest RH was in April in the Rain Forest (65.1% ± 1.24). Notably, March RH was 
highest in the Coastal belt (73.2% ± 1.14), with standard deviations ranging from ±0.89 to 
±2.11 across the sampled months. ANOVA results showed statistically significant spatial RH 
difference in March (F = 8.4, p = .000) and June (F = 7.0, p = .001), but not in January, 
February, April, or May (at p > .05). A consistent diurnal RH pattern emerged with RH peaked 
at 00:00 hrs. (85% in June) and dropped by 12:00 hrs. (68%). Performed spatial mapping 
revealed highest RH in Khana, Andoni, and Ahoada West (69.58%), and lowest in urbanized 
LGAs like Port Harcourt (65.72%). These findings emphasize the urgent need for ecologically 
responsive building designs targeted at managing the excess indoor humidity, while enhancing 
thermal comfort in low-income housing.