I live in a 26' X 38' manufactured home. It does not have a basement. It is set up on concrete blocks about 2 1/2 feet from the ground with hard skirting all around. There are about 10 metal vents all around the skirting at various points on the skirting. I know that these are used for ventilation so that there is no moisture build-up underneath the home. I have cut up a plastic shower curtain liner and duct-taped the pieces over about 6 of the vents to keep the heat and/or cold from entering beneath my home during the day. I did this about 3 years ago and just yesterday replaced the plastic as the duct tape had degraded and some of the pieces had fallen off. It is decidedly cooler in my house today with an outside temperature of 88 degrees. Yesterday it was the same temp. but it was hot inside so I had two air conditioners running during the day. I can't believe how much cooler it is today inside without either air conditioner going. Has anyone else done something like this?