During what condition does radiation become the dominant means of heat transfer?

Radiation becomes the dominant means of heat transfer during full room involvement because, in this scenario, the entire space is filled with flames and heated gases. At this stage, the heat radiating from the fire can impact all surfaces within the room directly, as there are no longer obstacles or cooler areas to absorb or diffuse heat before it reaches those surfaces.

In a fully involved fire, the intensity of radiation increases significantly as the fire spreads and the temperature rises, allowing heat to transfer not just through the air but also through electromagnetic waves, impacting items across the entire room. This process is crucial in firefighting and fire investigation as it influences how damage occurs and how quickly the environment can become dangerous to those inside.