Abstract: To find out the heat flux of the north wall of the greenhouse,and identify proper thickness of the wall,the temperatures of different depth at top,middle and bottom of the wall,and the air temperatures near inner/outer surface of the wall,were measured. It was showed there were constant temperature layers at the depth of 40-50cm.The heat fluxes at the depth of 40cm were mere 4W·m-2. The calculation result showed that the natural convection of the air near inner surface of the wall was on turbulent flow state,and the convection heat index was 1.69~4.43W·m-2·K-1. The maximum convection heat flux of the inner surface of the wall was 26.5W·m-2 in clear daytime and the wall absorbed radiation 83.6W·m-2 maximally. The conduction heat flux reduced and the phase of the heat flux lagged along with the increase of the depth. The heat flux decreased sharply from clear day to cloudy day. The conclusion was that 60cm was a reasonable thickness of the north wall of the solar greenhouse in zhengzhou,Henan province.

Key words: Solar greenhouse, Solar greenhouse, North wall, Convection, Conduction, Heat flux