The convective mass transfer coefficient on the outer surface of a building is an important parameter in the calculation of the heat and moisture coupling of the enclosure and the simulation of building energy consumption. To get the parameter directly and accurately

a method for measuring the mass transfer coefficient of the wall on the building surface is proposed. The mass transfer coefficient of the naphthalene specimen can be calculated by measuring the mass flux and surface temperature of the naphthalene specimen. To verify the accuracy and reliability of the method

6 different wind speeds were set up in the wind tunnel

and two pieces of the same experimental wall were made. The naphthalene sublimation method was applied to compare with the traditional thermal balance method. The results show that the surface temperature of naphthalene specimen decreases with the increase of wind speed

and the convective mass transfer coefficient increases gradually. The results of the two methods are close to each other. The difference of the convective mass transfer coefficients between the two methods are less than 10%

and the average deviation is less than 5% under different wind speed conditions. It is considered that the method is feasible. The research can provide guidance for testing the mass transfer coefficient of building external surface under outdoor real conditions

and is also significant for the study of heat and moisture coupling calculation and the evaporation and heat transfer of walls.