21. Using low emissivity glass on surface # 2 will add another R-value. 22. The emissivity of a natural interface is always between = 0 } } and 1. 23. Each material has a different emissivity , which may vary by temperature and infrared wavelength. 24. A shiny metal surface has low emissivity . 25. Therefore, it is possible to create visibly dark colored surfaces with low thermal emissivity . 26. The absorption spectrum measured by THEMIS contains two kinds of information : temperature and emissivity . 27. Real world objects are gray objects, with their absorption being equal to their emissivity . 28. For aged conductor, the emissivity for heat radiation and the absorption of sunlight increases. 29. At any given wavelength the absorptivity of the atmosphere will be equal to the emissivity . 30. From RCA and textbooks, emissivity of oxide coated filaments is about 0.3.
