Second, a small fan motor blows out hot air from the roof vent on top of the clock.

Unfortunately, they spent more on the mechanics than expected, and had to put in roof vents to get more light inside.

The main area can be closed off at both ends and reacts to the weather outdoors through a sequence of programmed louvers and roof vents.

Another example would be the emissions from an automobile paint shop with multiple roof vents or multiple open windows.

In less populated areas with good air movement dissolution and dispersal techniques for odour management may be employed i.e. ventilation from high points such as a chimney or roof vents.