Our group is developing multifunctional TiO₂/SnO₂:F stacked-films with both photocatalytic and low-emittance properties. The thin-films of TiO₂ are formed on SnO₂:F-coated glass substrates by reactive magnetron sputtering under various deposition conditions. Control of the electronic structure in the near-surface region is the key to obtaining excellent photocatalytic performance, which is confirmed by low-energy electron energy loss spectroscopy in the core electron excitation regions. The application of these films to energy-efficient-windows allows the possibility for reducing the energy load of the heating system and making the living space comfortable.