| # | Company name | Role | # of projects |
|---|---|---|---|
| 1 | C & K | MEP engineering | 8 |
| 2 | C & K | MEP engineering | 3 |
| 3 | C & K | MEP engineering | 2 |
| 4 | C & K | MEP engineering | 5 |
| 5 | C & K Development Co. Limited | MEP engineering | 1 |
| 6 | C. Colomina G. Serrano S.A. | MEP engineering | 1 |
| 7 | C&B Consulting Engineers | MEP engineering | 38 |
| 8 | C&R Mechanical Company | MEP engineering | 15 |
| 9 | C3 | MEP engineering | 1 |
| 10 | Cain Ouse Associates, Inc. | MEP engineering | 32 |
| 11 | Canzler Ingenieure GmbH | MEP engineering | 1 |
| 12 | Carastro & Associates, Inc. | MEP engineering | 5 |
| 13 | Carlos Gerade | MEP engineering | 1 |
| 14 | Carter & Burgess, Inc. | MEP engineering | 6 |
| 15 | CCRD Partners | MEP engineering | 18 |
| 16 | CCRD Partners | MEP engineering | 1 |
| 17 | CCRD Partners | MEP engineering | 11 |
| 18 | CCRD Partners | MEP engineering | 1 |
| 19 | CEC & Tao, Williams & Associates | MEP engineering | 1 |
| 20 | CEMOPE Consultoria e Projetos | MEP engineering | 13 |