Turn off all burning appliances, such as gas stoves and water heaters, and close all windows, exterior doors, and fireplaces. Turn on all ventilation fans that blow the air outside. If you don’t have an exhaust fan in your bathroom and your kitchen fan isn’t venting outdoors, open a window and install a fan to blow indoor air out; Seal the openings around the fan with cardboard. Then light a stick of incense and watch the smoke fly as you move the stick around ceiling lights, electrical outlets, door and window frames, baseboards, attic hatches, and whatever where pipes or wiring penetrate walls or ceilings.
https://www.washingtonpost.com/home/2021/11/23/upgrade-home-insulation-prevent-drafts/?utm_source=rss&utm_medium=referral&utm_campaign=wp_lifestyle How to upgrade the insulation in your home