This Lighting Guide replaces the CIBSE Applications Manual Window design which was published in 1987. The aim has been to build on the strengths of that manual and to update the design guidance and the way in which it is presented.Daylighting and window design is essentially a daylight design guide and a major part of the content deals with this topic. When daylighting decisions are made, however, they will have implications for other, interrelated aspects of window performance such as solar heat gain, winter heat loss, provision of view, acoustic performance, privacy, security and protection from fire. The Lighting Guide signals the need for designers, whether architects or engineers, to consider these interrelated factors and to determine priorities for their relative importance. There is detailed design guidance on the main daylighting issues and sufficient information on the related issues to establish design priorities. There are also ample references throughout the text to CIBSE publications and other important sources of information.Daylighting and window design has been written primarily for use when new design work is to be undertaken. However, much of the guidance will be applicable to refurbishment projects, although there may be constraints on the choices available for maximising daylight. The guidance in this publication is most applicable to projects in temperate climates where overcast sky conditions predominate.