The design, construction, and testing of an open-ended roof channel to reduce attic temperature
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Date
1998-08-01T00:00:00Z
Authors
Berrub, Myra Joyce
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Abstract
Solar gain can cause temperatures in buildings to become extremely high. A channelled roof with continuous openi gs, at the eave and ridge, was designed to generate anabatic cooling. The bottom plate of the channel was traditional roof decking. The top plate was formed galvanized steel sheathing. The force behind reducing heat gain was convective flow. Three units were constructed: one control unit with a simple roof of formed galvanized steel sheathing, one 40 mm deep channelled roof unit, and one 90 mm deep channelled roof unit. The attic temperatures in the 40 mm channelled roof unit were 0 to 3$\sp\circ$C lower than those in the control unit, and the attic temperatures in the 90 mm channelled roof unit were 1 to 4$\sp\circ$C lower than those in the control unit. The attic temperatures in the 90 mm channelled roof unit were lower than those in the 40 mm unit by 1$\sp\circ$C. In the south roof channel, the temperatures at the ridge were greater than those at the eave. Therefore, it appeared that heat flowoccurred up the roof slope by natural convection. In the north roof channel, the temperatures at the eave were greater than those at the ridge. Thus it appeared that heat flow occurred down the roof slope by forced convection, driven by wind. The influence of wind was observed for wind speeds between 15 and 39 km/hr. As wind increased from moderate to strong, heat flow in the roof channels became more steady, flowing from the ridge to the eave. Furthermore, forced convection occurred constantly in the 90 mm channelled roof unit for the observed wind speeds, while it occurred constantly in the 49 mm unit only at high wind speeds. (Abstract shortened by UMI.)