This damp crawl space is a breeding ground for germs. Notice the air ducts that run through this crawl space. When high humidity levels exist, it is much more difficult to control the temperature of that space which causes the cold air in the vents to warm up before it has a chance to cool the rooms above in the summer or heat them in the winter when the temperature in the crawl space is very low. Encapsulating and insulating your crawl space will help reduce your energy bills.