| Business | Phone |
| Matt Coil-Less Burner Co 4011 W Lake St, Chicago 60624 | (773) 638-1315 |
| Northbrook Energy 20 N Wacker Dr, Chicago 60606 | (312) 419-1221 |
| Soto Insulation Inc 3815 S Ashland Ave, Chicago 60609 | (773) 376-2982 |
| High Tech Insulation Inc 4520 W Lawrence Ave, Chicago 60630 | (773) 685-5100 |
| People's Energy 6659 N Kedzie Ave, Chicago 60645 | (773) 338-3186 |