Abstract:
Heat influx through roofs is the leading cause of internal temperature imbalance problems in
buildings. Roofing materials and configurations are key in regulating heat infiltration into buildings.
There is a dearth of information on their synergistic contribution to the control of internal
temperature imbalance. This study was designed to investigate the thermal performance of selected
roofing sheets and underlays, under different configurations in residential buildings in Ibadan.
Plywood-Lined Aluminium Roof (PLAR) and Selected Roofing Materials (SRM) [Stone Coated
Sheets (SCS) and Aluminium Roofing Sheets (ARS)], were tested using ice and steam apparatus for
5 and 7 minutes, based on UNE EN standard. These and Selected Ceiling Materials (SCM)
[Polyvinyl Chloride Ceiling (PVC), Asbestos (ASB), Plaster of Paris (POP), Gypsum (GYP) and
Plywood Ceiling Board (PCB)], were tested using fabricated conductivity apparatus, for Thermal
Conductivity (TC) (W/mK), Thermal Resistivity (TR) (mk/w), Thermal Diffusivity (TD) (m2/s),
Specific Heat Capacity (SHC) (J/kgK), and Thermal Absorptivity (TA) (J), based on ASTM
standards. Forty-five prototype buildings were constructed using a factorial combination of three
roofing sheets, five ceiling underlays, and three angular configurations. Optimum Comfortability
Roof (OCR) for the buildings were obtained using multichannel data logger between 9 am to 10 pm
at 30 minutes interval for six months. Data were analysed using descriptive statistics and ANOVA
at α0.05.
The TC; 135.60-150.62 (TCPLAR), 83.680-97.069 (TCSCS), and 76.149-123.43 (TCARS); indicated
PLAR was a suitable heat conductor. The TR; 0.0066-0.0074 (TRPLAR), 0.0103-0.0119 (TRSCS), and
0.0081-0.0131 (TRARS), implied PLAR has poor heat resistance. The SHC; 3.726-4.739 (SHCPLAR),
3.164-8.887 (SHCSCS), and 2.180-7.082 x 103 (SHCARS), indicated the heat storage potential of
PLAR. The TD; 1.066-1.507 (TDPLAR), 1.390-3.095 (TDSCS), and 1.021-2.643 x 10-7 (TDARS);
implied heat diffuses slowly through PLAR. The TA; 392.66-398.09 (TAPLAR), 425.18-491.07
(TASCS), and 327.73-380.55 (TAARS), indicated that PLAR possessed good heat absorption.
Similarly, TC for underlays; 0.191 (TCPVC), 0.125 (TCASB), 0.184 (TCPOP), 0.228 (TCGYP), and 0.283
(TCPCB), indicated that PCB was an insulator. The SHC; 1.654 (SHCPVC), 2.050 (SHCASB), 1.596
(SHCPOP), 2.070 (SHCGYP), and 2.850 x 103 (SHCPCB), showing that PCB had a better storage
capacity. The TD; 1.360 (TDPVC), 0.399 (TDASB), 1.266 (TDPOP), 1.410 (TDGYP) and 0.456 x 10-7
(TDPCB), showed that PCB diffused heat slowly. Also, TA; 319.00 (TAPVC), 338.24 (TAASB), 336.93
(TAPOP), 334.24 (TAGYP), and 353.43 (TAPCB), suggested higher TA in PCB. The temperature of the
SCM decreased with increase in the angle of configuration. The average temperature at 30, 45, and
60°, for 6 pm and 10 pm were; PLAR (37.04-29.74, 35.5-28.66, 31.02-28.64°), SCS (37.14-26.28,
35.18-26.38, 37.28-28.06°), and ARS (36.97-29.7, 38.72-30.16, 37.82-29.58°), respectively,
implied that between 45° and 60° gave OCR ranged 22 - 29°, with the highest coefficient of
correlation (R2 = 0.95, 0.70, 0.90) obtained. A significant difference between the OCR of SRM and
SCM was observed.
Plywood-lined Aluminium, stone-coated and Aluminium roofs configured between angles 45° and
60° offered acceptable thermal performance with the plaster of paris or polyvinyl chloride as roof
configurations in Ibadan.
