Empirical Study of the Effectiveness of Traditional Roof Forms in Reducing Solar Heat Gain in Buildings in Kano State

Traditional roof forms in Kano State, North West Nigeria, including the Hausa flat mud roof with parapet and the pitched corrugated iron roof, were developed within a vernacular knowledge framework to address local thermal conditions, yet their comparative effectiveness in reducing solar heat gain has not been empirically quantified. This study empirically measured and compared solar heat gain and indoor thermal conditions in buildings with four roof types: traditional flat mud roof, corrugated iron pitched roof (30-degree pitch), insulated corrugated iron roof, and reinforced concrete flat roof, at matched test buildings in Kano Municipal Local Government Area. Roof surface temperatures, underside temperatures, indoor air temperatures, and horizontal solar irradiance were monitored continuously for 8 weeks during the hot dry season. Roof thermal resistance values were determined from heat flux measurements. Results showed that the traditional flat mud roof produced the lowest peak indoor temperatures (mean: 32.4 degrees Celsius), significantly lower than the uninsulated corrugated iron roof (mean: 41.7 degrees Celsius) and the reinforced concrete flat roof (mean: 38.2 degrees Celsius). Thermal resistance of the traditional mud roof was 1.84 m2K/W, more than double that of the uninsulated corrugated iron roof (0.78 m2K/W). The insulated corrugated iron roof achieved comparable thermal resistance to the mud roof (1.71 m2K/W). The study provides empirical validation for the thermal superiority of traditional mud roofing in Kano State conditions and recommends its promotion in building guidelines for the North West zone.

Keywords: roof thermal performance, solar heat gain, traditional roofing, Kano State, hot dry climate