What characteristic of a fire compartment can decrease the potential for flashover?

The characteristic of high insulation properties in a fire compartment is significant in decreasing the potential for flashover. Flashover occurs when all combustible materials in a room ignite simultaneously, leading to a rapid spread of fire. High insulation can help to slow down the heat transfer within the space, thus preventing the room from reaching the temperatures necessary for flashover to occur.

Insulation materials can reduce the chance of the temperature rising quickly to ignition levels by retaining heat and maintaining a more stable environment. This means that as the fire develops, it may take longer for the surrounding materials to reach their ignition point, thereby reducing the risk of widespread combustion that characterizes flashover.

The other options, such as having open windows, large volumes of flammable materials, or high humidity levels, do not contribute positively to fire safety. Open windows can introduce additional oxygen to the fire, which can actually facilitate a flashover instead of reducing it. Large quantities of flammable materials increase the likelihood of rapid fire spread, and high humidity levels may not effectively prevent the ignition of combustibles within the compartment, especially with the addition of heat. Therefore, the characteristic of high insulation properties is the best answer for decreasing the potential for flashover.