The Solutions

Pre-renovation, the Lourdes facility consumed 11% more energy than the median US hospital property and spent 16% more in total energy costs, indicating a clear opportunity for improvement. However, no funding was available for a large-scale replacement of these aging HVAC systems, which would have been the conventional approach for immediate improvement. This posed a unique challenge for CMTA: to make significant energy improvements at the facility without additional financial investment, apart from the engineering and balance fees required to accomplish this work. To meet these goals, CMTA applied an innovative retro-commissioning strategy to the hospital’s existing building systems. A common misconception about retro-commissioning is that it’s meant to reset the systems back to how they were originally designed to operate. However, retro-commissioning is meant to adjust and optimize systems for present-day operational needs, taking into account the evolved functions of the building.

CMTA reviewed 30 major HVAC systems as part of the retro-commissioning process, focusing on the engineering evaluation of six main areas:

• Ventilation Optimization: Reviewed major systems to ensure that the system’s ventilation was not only per original design but also matched the needs of the spaces as they were currently being used.
• Air Change Rate Analysis: Reviewed crucial hospital airflows across the facility to confirm that air change rates matched or exceeded code-required minimums. Codes and, in some cases, the use of the spaces downstream had changed. This process required a fresh engineering evaluation of each system as to how it was being used in light of current codes.
• Static Pressure Setpoint Evaluation: Reviewed each system’s existing setpoints, and collected test and balance information, revealing areas for optimization.
• Scheduling & Use Study: Evaluated all major systems based on the areas of the building they serve and ensured that their operation matched the current use of each space.
• Steam Infrastructure Evaluation: Surveyed the existing steam trap and condensate return system and replaced failed steam traps.
• Future Master Planning: Provided the facility with a roadmap to strategically use future capital dollars as they become available to maximize future utility savings.

The systems analysis revealed that many systems were operating at levels far above code-minimum due to legacy control sequences. For instance, several air handling units (AHUs) were operating per their original intent while the use spaces downstream had changed over time, resulting in air change rates and static pressures far exceeding necessary levels. To address this, the project team revised designs to reduce fan speeds and fine-tune VAV systems by adjusting operational schedules, aligning with the present needs of the serviced areas. Twenty-seven low to no-cost strategies were implemented as part of the retro-commissioning process, accomplishing significant energy and cost savings.