Emissivity is the ratio of energy emitted by a material. Emissivity values range from 0 to 1. Basically, the value if low, means that the material will hold its heat longer then a value with a high value as the ambient temperature drops during the day.
Total Solar Absorptance is ratio of the amount of total solar energy absorbed by the object to the amount of total solar energy falling on the object. Solar absorption is that portion of total solar energy neither transmitted nor reflected. Since solar transmittance and solar reflectance are measured directly, the following equation should be used in calculating solar absorption. Solar absorption =1.00 – (solar transmittance) – (solar reflectance). Generally the lower this number the better. This number is a critical determinant in the potential for thermal stress.
Total Solar Reflectance is the ratio of total solar energy which is reflected outwardly by the object to the amount of total solar energy falling on the object. Value is usally expressed as a percent. The higher this number the better.