In Episode 7, check out UL's Fire Safety Research Institute (FSRI) Advisory Board Member and Division Chief for Montgomery County (MD) Fire & Rescue Service, Charles Bailey, as he explains how heat transfers through turnout gear:

One of the most important lessons we as firefighters must understand is the use and limitations of our PPE. While we may not be able to out-perform the thermal limitations of our turnouts, by applying the right tactics, we can certainly enhance our operational effectiveness and reduce the potential for thermal insult/injury.

Additional resources related to this consideration:

Article: Thermal response to firefighting activities in residential structure fires: the impact of job assignment and suppression tactic

Report: Fire Fighter Equipment Operational Environment - Evaluation of Thermal Conditions