Solar and air lumber drying during winter in Virginia

A greenhouse-type solar lumber dryer with a transparent south wall and transparent 45 degrees sloped roof was used to dry 4/4 oak lumber in the winter in Virginia. A pile of end-matched samples was also air-dried during the same time period. The solar-dried lumber reached 20 percent moisture content (MC) in 80 days and 6 percent MC in 125 days; the air-dried pile reached 20 percent MC in 105 days and 14 percent MC in 162 days. Solar-dried lumber at 6 percent MC was without end checks and free of casehardening stresses. In order to permit comparisons of this dryer with other dryers or after modification of the existing dryer, a method of calculating an efficiency factor using standard meteorological data is explained. (Refs. 17).