In addition to the operational energy and carbon footprint due to HVAC, the building insulation material is also considered an emission source, known as embodied carbon. Commonly used materials such as expanded polystyrene, extruded polystyrene, and polyurethane have more than 4 kgCO 2 eq./kg carbon footprint, aggravating global warming. (Figure ) It is attractive to reduce the carbon emission of the thermal insulation layer during building construction. Because of our device's dynamic tunability, we anticipate it can reduce the usage of the thermal insulation layer by adapting to the varying external environment, rather than merely shielding from it. In Figure , we calculate the energy saving percentage for buildings with different thicknesses of the insulation layer in Helena and their corresponding carbon footprint of the thermal insulation layer. The calculation method is shown in the Supplementary Note 2. In EnergyPlus, the insulation layer's default thickness (100%) is 0.119 m and 0.127 m for Steel Frame Wall and Roof, respectively. As we decrease the thickness of the thermal insulation layer from 100% to 25%, the embodied carbon footprint of the building can be reduced from 12170.2 to 3042.6 Kg CO 2 eq., and up to 19.44% of HVAC energy can be saved with the help of the Cuaqueous electrochromic device. The results demonstrate that the Cu-aqueous mid-IR modulation device can save more percentage of operational HVAC energy for low carbon footprint buildings (fewer insulation materials used), outperforming the constant low-e and high-e envelope, especially when installed on buildings with poor thermal insulations for retrofitting. (Figure )