This guide gives an introduction to the key principles of natural environmental ventilation and smoke control in the event of fire, considers how to combine these strategies to achieve a successful design, describes a simple design tool, and presents two illustrative examples and their design implications. This guide aims to increase awareness of the possibilities for combining natural environmental ventilation in atria with smoke control so that this can be considered at the detailed design stage, thus optimising performance. 16 pages. Download the design speadsheet at http://projects.bre.co.uk/atriumsizer/