This is a particularly challenging situation for larger buildings with high roofs, typically used in factories, warehouses and some retail units and event spaces. And while these buildings may share a similar style, in terms of height, the activities inside will vary considerably so the ventilation requirements will vary too. Plus, of course, such buildings often change in use over a period of time.

Some years ago, these types of building were sufficiently ‘leaky’ that natural ventilation through the gaps in the building structure was sufficient for all but the most demanding environment. Now, as building insulation has improved to conserve energy, more precise control is required to ensure acceptable IAQ – ideally whilst optimising energy efficiency.