Study On Evaluation Method For Heat Insulation Performance Of Cool Metal Roof Plate

Cool metal roof plate has been one of new energy-saving roofing material because its surface course is the solar heat reflective coating with higher solar reflectance and hemispherical emittance. The prospect of cool metal roof plate is quite wide under these circumstances that the metal roof is increasingly received and the energy-saving policy is carried out. The paper relates the test method for the heat insulation performance and environmental adaptability of cool metal roof plate except evaluation on the heat insulation performance of cool coloring metal roof plate.It was not comprehensive that solar reflectance and hemispherical emittance were used to characterize the heat insulation performance of cool metal roof plate. Through analyzing the heat balance of roof and simulating the service environment of cool metal roof plate, the concept of insulation factor was put forward for characterizing the heat insulation performance. Meanwhile, the test equipment for the heat insulation performance of cool metal roof plate had been researched. On the basis, the test method for the heat insulation performance of cool metal roof plate was established. The method not only right reflect the heat insulation performance of cool metal roof plate but also make up for deficiency of characterizing heat insulation effect of heat reflecting metal roof plate using the solar reflectance and the hemispherical emittance.As the functional roof materials, the environmental adaptability of cool metal roof plate depends on the solar heat reflective coating located in its surface. According to related national standards with contamination resistance and artificial weathering, the sample was tested and the pre-and post value of solar reflectance and hemispherical emittance was measured. Furthermore, it is not obvious that the environmental factor effect on the hemispherical emittance of solar heat reflective coating, so the change of hemispherical emittance can not be considered as the index of evaluation on environmental adaptability of solar heat reflective coating. Finally, the change of solar heat reflective under the compound effect of contamination and aging can be used as the key index which reflects the environmental adaptability of solar heat reflective coating.The abundant color and function of cool metal roof plate originates from the solar heat reflective coating. The evaluation for the heat insulation performance of coloring heat reflective coating is the basis for the evaluation for the heat insulation performance of cool metal roof plate. The paper described the relationship between lightness and visible area reflectance, near infrared area reflectance and solar reflectance. According to the relationship, coloring heat reflective coating was divided into three types:high lightness solar heat reflective coating, middle lightness solar heat reflective coating and low lightness solar heat reflective coating. Besides, the basic limit value of solar heat reflective coating and the requirement of high performance solar heat reflective coating were stipulated. On the basis, the evaluation index and limited condition for the initial heat insulation performance were determined.