We used Illinois Energy on 2 separate jobs which includes 5 windows and a patio door and we loved using them. From the sales process all the way through they were thorough, responsive and high quality. We liked them so much we used them 2 times and both times was a great experience. I am beginning to get tired of big corporations churning through clients so when I find a company like this that is a local business that does great work I am happy to recommend them. They are great!