Horizontal shading devices - such as overhangs, brise soleils, louvres and light shelves - are often very effective in reducing peak summertime solar gains. This Information Paper quantifies the effects of these devices. It gives data that can be used as correction factors for the method shown in Appendix H of Approved Document L2 (2002 edition) of the Building Regulations, as a way to meet the requirement to limit solar overheating in buildings other than dwellings. 4 pages.