Final answer:
Vertical ventilation is better than horizontal because it enhances smoke removal, prevents thermal layering, and is easier to control, making it more effective during fires in buildings.
Step-by-step explanation:
When considering the effectiveness of ventilation techniques in buildings, particularly for smoke removal during a fire, vertical ventilation is considered better than horizontal ventilation for several reasons. Firstly, vertical ventilation allows for better smoke removal because it takes advantage of the natural tendency of hot gases and smoke to rise. By creating an opening at a high point, such as a roof or the top floor of a building, you allow these hot gases and smoke to escape directly upwards into the atmosphere, improving visibility and reducing the risk to occupants and firefighters.
Secondly, vertical ventilation can help prevent thermal layering, a phenomenon where different temperature layers are formed within a space – colder air below and hotter air above. By opening vents above the fire, you break these layers and allow for an even temperature throughout the room, reducing the risk of flashover, which is the rapid ignition of combustible materials in a confined space.