The　rapid　advancement　of　spectrally　selective　materials　has　enabled　the　development　of　smart　windows　that　can　regulate　different　bands　of　solar　radiation.　However,　existing　methods　for　calculating　spectral　properties　vary,　leading　to　inconsistent　results　when　evaluating　their　light-electricity-heat-color　performance.　Therefore,　this　paper　presents　five　methods　for　calculating　window　spectral　properties,　intending　to　compare　and　identify　the　most　effective　approach　for　assessing　building　thermal　performance,　energy　efficiency,　and　daylighting.　The　methods　focus　primarily　on　the　solar　spectrum　input　and　the　glazing　spectrum　response.　The　solar　spectrum　inputs　include　the　Beijing　local　solar　spectrum,　ASTM　G173-03,　and　ISO　9845　(methods　S1　to　S3),　and　the　glazing　spectrum　response　methods　differ　based　on　whether　they　account　for　spectral　selectivity　and　the　choice　of　spectral　weighting　functions　(methods　S3　to　S5).　The　findings　reveal　that　variations　in　solar　spectrum　input　have　a　minimal　effect　on　window　performance,　while　differences　in　glazing　spectral　response　calculations　significantly　impact　results.　It　is　particularly　evident　in　thermochromic　windows,　where　discrepancies　in　energy　efficiency,　specifically　in　lighting　load,　can　reach　up　to　67.21　%,　and　variations　in　dynamic　daylighting　performance,　specifically　in　Useful　Daylight　Illuminance　(UDI)　below　500　lx,　can　be　as　high　as　28.27　%.　To　provide　more　accurate　assessment　results　of　glazing　windows,　this　study　recommends　using　the　spectral　calculation　method　S1,　which　incorporates　the　local　solar　spectrum　and　applies　the　standard　luminous　efficiency　function　to　the　glazing　spectrum　response.　This　paper　highlights　that　further　refinement　of　spectral　calculation　methods　will　enhance　their　utility　for　performance　evaluation　and　guide　the　reverse　design　of　innovative　window　features.