In heating, ventilation, and air conditioning (HVAC) applications, wet bulb temperature is an essential parameter for designing the equipment. But during the wet-bulb temperature measurement, radiation from the surrounding surfaces generated the errors. In this work, we have measured wet-bulb temperature using an Aspiration psychrometer and tried to minimize the errors term. It has been observed that the error term depends on parameters like airspeed, wick cloth properties, human breathing distance between the thermometers.  Here terms of the error have been calculated and observed that at higher mean radiant temperature, term of error is more. For large heat exchange with the surrounding environment leading to more terms of the error in the wet-bulb temperature measurement. Humidity ratio % error was also calculated.