Description Existing software tools for simulating light vary in the methods used to represent the spectrum of daylight and electric light sources throughout architectural scenes. Until relatively recently, lighting simulations were primarily used to predict photopic quantities, characterized by the human visual response V(λ), at the horizontal task-plane. The need to estimate the spectral characteristics of light reaching the eye of occupants for prediction of non-visual physiological responses, with spectral sensitivities that differ from V(λ), has motivated the development of new lighting software tools such as ALFA and Lark. The present study compared ALFA-predicted spectral irradiances and photopic illuminances to corresponding measurements captured in a laboratory environment with LED luminaires.