Many. My entire apartment is filled with large single pane windows. There's zero draft sealing at any of them, nor the front door. I likely pay an additional $1

Many. My entire apartment is filled with large single pane windows. There's zero draft sealing at any of them, nor the front door. I likely pay an additional $100 in electricity a month due to this. It was noticeably reduced when I took the time to 3M wrap all my windows one winter, but I didn't want to do it again.