Instant Energy Savings Through Retro-Commissioning
In 2021, Mercy Health decided to pursue its “commitment to developing a sustainable culture through environmental stewardship” by analyzing energy use across its older facilities. Together with CMTA, they identified Lourdes Hospital—a 306-bed regional hospital in Paducah, Kentucky—as the least energy-efficient in their network. Based on the facility energy and cost data collected, CMTA implemented a retro-commissioning approach with a focus on low to no-cost solutions to achieve energy efficiency for the hospital’s aging systems.
Project At A Glance
Size: 563,000 square feet
Pre-Cx EUI (2014): 390 kBtu/SF/yr
Post-Cx EUI (2022): 336 kBtu/SF/yr
Carbon Reduction: 807 metric tons CO2e per year
Water Reduction: 672,000 gallons per year
ASHRAE International Technology Award
Review all existing systems and identify areas for optimization
Implement low to no-cost solutions to improve the facility's energy performance with no changes to existing systems
Reduce the facility's operational carbon footprint and water usage
Thank you to CMTA for being such a great and valued partner not only to this hospital but our system as a whole. This project was a tremendous success story that continues to pay for itself to this very day!
Bon Secours Mercy Health System Director of Infrastructure
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.
This project disbands the myth that new construction and extensive renovations are the only pathways to impactful improvements. The facility team recouped their modest investment of retro-commissioning fees within six months of implementation! The commissioning team predicted the cost impact of these changes to be from $110,000 to $170,000 per year. However, after reviewing the facility’s utility cost data, these changes resulted in an adjusted energy cost savings of $212,250 in its first year. As utility rates continue to rise, these savings should increase.
In addition to surveying and identifying low-cost and no-cost changes, part of the retro-commissioning process was assisting the facility in prioritizing future energy-saving investments. A full survey collected data on the facility’s existing HVAC systems and established a ranking system for replacement or upgrades. As a result, the facility now has a roadmap to continue improving its energy efficiency and maximizing the impact of future infrastructure dollars.
Ventilation is critical to patient health and safety. To optimize the facility’s ventilation, CMTA surveyed all major air handling systems to track and observe the air handler outside air dampers’ operation. In many cases, we found that the existing systems were operating far above the minimum outdoor air rate for which it was designed, as the dampers were no longer controlled by the building automation system. Identifying and correcting this issue led to savings of nearly $10,000 per year.
CMTA’s retro-commissioning approach reduced the hospital’s carbon footprint by more than 807 metric tons per year. In addition, energy modeling of these impacts revealed a cooling tower water savings of 1,045,000 gallons each year—the equivalent of nearly four Olympic-sized swimming pools. Buoying these impressive results is the fact that carbon-heavy construction was unnecessary to accomplish them. Instead, all emission reductions positively impacted the environment.
CMTA was proud to help Mercy Health minimize both its environmental impact and its utility costs—all with minimal financial investment. This project demonstrates that meaningful environmental progress doesn’t always require carbon-intensive system replacements, but rather, the smart application of innovative retro-commissioning processes can revitalize the existing infrastructure.