Disclosed herein are systems, methods, and apparatus for forming adjustable windows may include a substrate and a first conducting oxide layer formed over the substrate. The adjustable windows may further include a spectral tuning layer formed over the first conducting oxide layer and an ion conductor layer formed over the spectral tuning layer. The adjustable windows may also include an ion storage layer formed over the ion conductor layer and a second conducting oxide layer formed over the ion storage layer. In some embodiments, the spectral tuning layer may be configured to change an infrared transmissivity of the adjustable window. Furthermore, the spectral tuning layer may be configured to toggle a solar heat gain ratio coefficient of the adjustable window between two or more solar heat gain ratio coefficients.