The experimental investigation of the effects of materials and their surface colours on nocturnal cooling is presented. Two materials, galvanized steel and aluminium, were considered. Three plates of each material were used. One was painted black, the other white, while the third was left unpainted. Each of the plates (0.5 × 0.5 m) was used to cover a wooden box of dimension 0.5 × 0.5 × 0.24 m, made of 0.02 m thick plywood, thus producing an air tight arrangement. Six of such boxes were formed in all; three from galvanized steel and three from aluminium. Ambient temperatures, temperatures of the air inside the box and on the outside surface of the plates were measured between 19:00 hours and 06:00 hours for 6 months. Also measured was the relative humidity. Results obtained reveal that the plates’ performances greatly depended on how clear the night was. For very clear night, the black painted aluminium gave the best result, maintaining a temperature difference of 3–8°C with the ambient. For a partly overcast night, the best result of 1–5°C difference between the inside air and the ambient was recorded by the unpainted galvanized steel while on heavily overcast night the best performance came from the unpainted aluminium with a temperature difference of 1–4°C. Thus unpainted galvanized steel and aluminium are considered best in region where the night sky is hardly clear.

This content is only available via PDF.
You do not currently have access to this content.