An experimental study was conducted on green roofs under the semiarid summer climatic conditions ofWest Texas to investigate\nthe effect of soil type, moisture content, and the presence of a top soil grass layer on the conductive heat transfer through the roof.\nTwo soil types were investigated: uniform sand and local silt clay. Tests were also conducted on a control roof. A dual-needle heatpulse\nsensor was used to conduct thermal property tests on the soils. The tests reveal that unlike sand, the thermal conductivity of\nsilt clay did not increase continuously with soil moisture. Better heat transfer conditions were achieved when the sand and silt clay\nroofs were watered to a water depth of 10mm per day rather than double the amount of 20mm per day. The roof with silt clay soil\nhad the lowest fluctuation in inner temperature between daytime and nighttime. Green roofs with silt clay soil required more than\ntwice the amount of soil moisture than green roofs with sand to achieve similar roof heat transfer rates. The best net heat flux gains\nfor vegetated green roofs were 4.7W/m2 for the sand roof and 7.8W/m2 for the silt clay roof.
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