The thermal efficiency of aluminum roofing sheets lined with plywood and common ceilings in tropical buildings in Nigeria

Abstract

The main source of indoor discomfort has been identified as high solar radiation entering
through the roofs and ceiling layout. The synergistic combination of ceiling underlay and roofing sheet
was critical in controlling internal heat imbalance in the tropics. Hence, this works examined the impact
of lined and non-lined aluminium roofing sheet in the tropical buildings, Ibadan Nigeria. Three prototype
miniature buildings oriented north south were roofed with plywood-lined aluminum roofing sheets
(PLARS) and non-lined aluminium roofing sheet (NARS) configured against some common ceiling
underlay at various angles of 30, 45, and 60, respectively. Using a multichannel data logger, daily
temperatures were collected for six months at 30-minute intervals. Data were analysed using
descriptive statistics and ANOVA at α0.05. The findings showed that as configuration angle increases,
the temperature of the Sampled Ceiling Materials (SCM) and sampled roofing materials (SRM)
decreases. The average temperature at 30, 45, and 60°, for 6 p.m. and 10 p.m. in PLAR was 37.04-29.74,
35.5-28.66, 31.02-28.64°, showing a downward trend in temperature as the sunset approaches. Implies
a conducive indoor space for the inhabitant during the night. While the NARS was 36.97-29.7, 38.72-
30.16, 37.82-29.58°, implies a slightly higher air temperature at the twilight. However, the highest
coefficient of correlation (R2 = 0.95, 0.90) for PLAR and NARS obtained. The angles 30, 45, and 60 gave
the Optimum Comfortability Roof (OCR) between 22 and 29°, based on the ASHRAE standard.