Heat shadowing occurs when one object blocks the travel of heat from the heat source to the substance behind the shadowing object. The object causing the shadowing does not have to be a solid; it can be any substance that absorbs or reflects heat, protecting the material on the other side of it. Heat shadowing can produce protected areas. Protected areas are created when an object blocks the deposition of soot and combustion products on a surface and/or prevent the blocked substance from burning. Heat shadowing and protected areas can affect fire patterns and lines of demarcation that may have appeared on the shadowed material in the absence of the protective object. However, heat shadowing and protected areas can also help the investigator. If the investigator finds a protected area where the item that protected it is missing, it may indicate to him that someone moved the protecting item after the fire. Or, if contents of the room have been moved during fire suppression efforts, heat shadowing and protected areas can help the investigator reconstruct the pre-fire location of contents in the room.
For more information on this term, see the interFIRE VR Resource File article: Examples of Fire Patterns: Protected Area (Surface)