The aim of the study is to underline the contribution of colour in daylighting projects as an objective parameter of visual performance and pleasantness. Window technology offers ways to use daylight in buildings. Glazing, shading systems and indoor materials modify its aspect by offering a large variation of its colour. However, colour of daylight changes greatly according to climate, spatially and temporally. Variation of the colour of daylight is illustrated as well as an example of the resulting change of surface colours with or without a type glazing. Then, a method to predict directional colour of skylight is suggested with the intention to apply it in daylighting calculations. (C) 2001 Elsevier Science B.V All rights reserved.