when our front AC quit working the back air didn't shut off. We were in 110 degree heat in Nevada! We went to Lowes and bought a couple rolls of the silver insulation and put it on all the windows and windshield. We also have the sun screens on the windshield but the silver insulation helped much more. Works if you're staying in one spot for awhile. We also have the inserts for the vent fans and covered the skylight in the shower. Dark inside but a few degrees cooler.