Throughout history, natural ventilation has remained the preferred choice for the majority of residential buildings, while, in commercial buildings, natural ventilation went from being the single option to somewhat of a lost art as mechanical ventilation systems and air conditioning became the standard during the second half of the twentieth century. Recently, as a result of environmental concerns, in particular the greenhouse gas emissions from buildings, interest in natural ventilation in commercial buildings has seen a resurgence. Unfortunately, the hiatus in natural ventilation use in these buildings has resulted in the loss of existing design know-how and consequently limited new developments in a period during which comfort and indoor air quality performance standards have continuously risen. Nevertheless, the past 25 years has seen significant advances in our understanding of the fluid mechanics of natural ventilation and Architectural Fluid Mechanics has developed as a new subject. In response to these new scientific advances and in an attempt to restore confidence in the applicability of natural ventilation in practice, this paper presents ten questions about building natural ventilation that span the different scales of the problem, from an urban context down to the neighbourhood and the building itself. These questions are commonly asked when a designer is considering natural ventilation as the preferred means of cooling a non-domestic building, and the answers are intended to provide succinct links to the latest knowledge, identify areas that require additional research and assist designers in making appropriate decisions. (C) 2016 Elsevier Ltd. All rights reserved.