Energy Efficient Crawl Space Vent Energy efficient vent includes summer screen and winter sealer plate. Increases crawl space air flow by over 50%, aids and assists in reducing moisture. Crawl space vent can be installed, insulated and sealed from the outside of your home. Helps prevent pipes from freezing. Saves energy and helps to keep your crawlspace warm. Easy to use: open and close from the exterior. Keeps rodents and mice out.