This article in Science mag news is about a fabric that can, let more heat (via IR) out in hot weather, or flipped over, keep more heat in the cold Here is the Science article (not free). The fabric also lets gasses and humidity pass through because it has nano-pores. It has 4 layers: 2 outside layers of polyethylene and 2 thin layers of carbon black and copper. • outside when cold PE layer 1: IR clear, 24 µm thick carbon black: absorbs and emits IR copper: weakly absorbs and emits IR, reflecting? PE layer 2: IR clear, 12 µm thick • out side when hot The copper and carbon layers are in contact, but distinct layers. What I don't understand: If the copper is reflecting the IR re-emitted by the carbon layer (as news article says), why is not the IR being absorbed by the carbon blocked to the same extent? Does the closeness of the carbon layer to the copper matter? Are there wavelength differences in what's absorbed and emitted by the carbon, that could interact with copper differently?