Determining the emissivity and temperature of building materials by infrared thermometer

•A technique to determine the emissivity and temperature of construction materials.•The technique use an infrared thermometer and two contact thermometers.•The mean emissivity of seven materials was determined.•The range of emissivity we determined was similar to that in the literature.•The precision of the measurement is acceptable for practical application.

An infrared thermometer can be used to detect the temperature of materials not in-contact, in situ and in real-time measurement. The set emissivity is key to obtaining the accurate measurement. In this study, we investigated a novel technique to determine the emissivity and temperature of construction materials by using an infrared thermometer and two contact thermometers. These measured values were transformed into true temperatures by calibration equations to improve their measurement accuracy, then the emissivity and temperature of the materials were determined by regression analysis. The mean emissivity of seven materials was 0.937, 0.942, 0.944, 0.804, 0.802, 0.902 and 0.911 for black plastic, polyethylene plate, red brick, paper, cotton cloth, wood and flat glass, respectively. The range of emissivity we determined was similar to that in the literature. The precision of the measurement is acceptable for practical application. The method we developed is easy and inexpensive and could be used for other materials.