| # | Company name | Role | # of projects |
|---|---|---|---|
| 1 | A & G Engineering Ltd. | MEP engineering | 83 |
| 2 | A. Svendsen | MEP engineering | 1 |
| 3 | A.G. Consulting Engineering PC | MEP engineering | 2 |
| 4 | A.O. Reed & Company | MEP engineering | 4 |
| 5 | AB Teknoplan | MEP engineering | 3 |
| 6 | ABF Consulting Engineers | MEP engineering | 6 |
| 7 | ABF Consulting Engineers | MEP engineering | 1 |
| 8 | Able Engineering Inc. | MEP engineering | 33 |
| 9 | Abraham Joselow Associates PC | MEP engineering | 21 |
| 10 | Abraham Joselow PE, PC | MEP engineering | 8 |
| 11 | ABS Consultants, Inc | MEP engineering | 10 |
| 12 | Ace Parking Management | MEP engineering | 6 |
| 13 | ACR Engineering, Inc. | MEP engineering | 13 |
| 14 | Adelt Mechanical Works | MEP engineering | 1 |
| 15 | Advanced Engineering, Inc. | MEP engineering | 1 |
| 16 | Adviesbureau vanderWeele | MEP engineering | 5 |
| 17 | Adviesbureau Wiecherink BV | MEP engineering | 1 |
| 18 | AECOM | MEP engineering | 19 |
| 19 | afaconsult | MEP engineering | 1 |
| 20 | Affiliated Engineers, Inc. | MEP engineering | 35 |