On some rv's it is used to keep the holding tanks warm in freezing temperatures by trapping the warm air from the furnace. Though not by much it, does help insulate and keep the floor warmer.
Richard & Jill
2014 Flagstaff 832IKBS Classic Super Lite
2018 Silverado 1500 Crew Cab Z71 4WD All Star Edition
Camping since 1989, seasonal since 2000
Car Shredder Op/Tech, Scrap Metal Recycling - retired
The Faster I Go, The Behinder I Get.