Guard Heat is a statistic found in the top right corner of the in-game HUD. It increases by 10 upon being sighted by a guard outside of the denoted area, and can also increase by not showing up to Dinner, Exercise, Shower, etc; if you loot an inmate's body; started fight with any character of prison (guard/inmate); staying in inmate's cell; searching inmate's desk. Once above 89%, any guards will attack on sight and tower guards will attack you if you're walking in the yard. Guard heat gradually degrades if you're doing what you're supposed to. If your guard heat reaches 100% Lockdown will happen. Lockdown will also happen if you Knock Out 2 Guards. Knocking out Guards can cause your heat to rise more. When you are Knocked Out, the Guard Heat resets to 0.
In The Escapists 2, there isn't any Lockdown at 100% heat. Over 80%, any guards will attack on sight and tower guards will attack you if you're walking in the yard. When you are knocked out, the Guard Heat resets to 0%. You can surrender by pressing the F4 button, then F1 to confirm. You will reach 1 HP, you will be taken to the solitary and the Guard Heat will reset to 0.