Energy Sustainability: Retro-Commissioning Aging Facilities


Health Care

Energy Sustainability: Retro-Commissioning Aging Facilities

The primary goal of health care is to prevent disease and improve the quality of life. In this pursuit, environmental issues have suffered. Consider the following statistics:

  • Inpatient care is ranked by the EPA as the second largest commercial energy user in the U.S.
  • Health care facilities consume close to 10% of the total energy used in U.S. commercial buildings, spending over $8 billion dollars on energy a year.
  • The health care sector creates 8.5% of U.S. greenhouse gas emissions.

While physicians are rarely responsible for making decisions about facilities energy usage, some baseline knowledge around these issues may prove useful. To commit to a “do no harm” policy by working to eliminate the negative health and climate impacts of their energy consumption. Recently named a recipient of the Practice GreenHealth “System for Change” award, BSMH believes in a commitment to developing a sustainable culture through environmental stewardship and working with others now and in future generations. Sustainability initiatives for BSMH have included obvious measures such as recycling, using more sustainable products and implementing energy-efficient systems and practices as part of new construction projects. But there were other ways to save money and improve efficiency within their current systems and buildings that do not bear a heavy price tag. 

A growing potential for savings has been identified in older and aging facilities.

Facilities Sustainability

Sustainability initiatives don’t need to be limited to new construction projects or large expenditures. Recently, a growing potential for savings has been identified in older and aging facilities. Older HVAC systems generally were not energy efficient in their original design and the impact of time on these systems often leads to a worsening of their energy impact. In addition, changes in the use of facilities over time can lead to energy-intensive systems used in areas that no longer truly need such systems. Rising utility costs further underscore the need for change in some of these older facilities. 

To combat these forces, in the spring of 2021 BSMH partnered with CMTA to begin to collect energy data from some of its older facilities and conduct an exercise where this data was benchmarked to compare one facility to another. One common building benchmark used as a measuring stick to compare energy use in facilities is the Energy Use Intensity (EUI). This is simply a ratio of the total energy used in each facility divided by the square footage of the facility. Calculating a building’s EUI allows a facility management team to assess how a given building performs relative to other similar buildings. These benchmarks are then compared with data from similar facilities around the country to assess need.

After BSMH completed its facilities benchmarking process, one facility stood out as the lowest performer – Lourdes Hospital in Paducah, KY. Lourdes Hospital is a regional hospital building with 306 staffed beds. This facility was significantly worse in energy use (12%) than the median US hospital property and 14% worse in total energy cost ($/sf).

Investments were planned for the facility to renovate several older building systems including the central utility plant, however, reducing utility costs and improving system efficiency prior to that became the priority. With this goal in mind, BSMH issued a challenge to CMTA: identify low-cost and no-cost changes which could be implemented at their facility to reduce emissions and utility costs immediately. These costs would need to focus on areas outside the central utility plant and the floors slated to be renovated. To meet the challenge, CMTA applied a retro-commissioning strategy to their existing building systems.

What is retro-commissioning? Many are familiar with commissioning: the process of verifying that the actual operation of an installed system meets its design. This has a simple application to new construction projects. But what about renovations or existing buildings? There is a process called retro-commissioning, however, this process often falls short in an existing facility.

Consider, for instance, the system that was designed 50 years ago and no longer is serving its intended purpose. Does re-commissioning such a system to verify that it operates in line with its 50-year-old design worthwhile? Most often, the answer to this question is ‘no’ and another solution is needed. Retro-commissioning is the process of marrying the active control and facility design with retro-commissioning to achieve improved energy performance and efficiency in older systems. This process is not limited to the verification of a sequence of operations written fifty years ago, but instead asks the question – ‘how should this system operate today, given the current use of the facility?’ The retro-commissioning process at Lourdes Hospital in Paducah, KY leveraged retro-commissioning in the following areas: ventilation optimization, air-change analysis, HVAC system speed, scheduling study, steam evaluation, and planning for the future. 

Ventilation Optimization

One key user of energy in a facility is the amount of outside air intake that occurs to keep the facility ventilated. Much of the ventilated air is a calculated amount and is required by local codes. However, deferred maintenance or equipment failure often leads to systems that allow far more outside air than required. This leads to large efficiency reductions and potentially, even comfort and humidity issues. To ensure that the facility ventilation system was optimized, we conducted a survey of all the major existing air handling systems to track and observe the operation of the air handler outside air dampers. As part of the survey, one air handler was identified which had dampers that had been manually adjusted but were no longer controlled by the building automation system (BAS). This led to the air handler operating far above the minimum outdoor air exchange rate as required by code. Identifying and correcting just this one issue led to savings of nearly $10,000 per year.

Air-Change Analysis

In addition to requiring a certain amount of outside air, codes require that hospital HVAC systems must circulate a certain volume of air through the unit filters every hour. This requirement is referred to as a system’s air-change rate. The issue that arises in older facilities is the use of spaces change, but air-change rates are often not re-evaluated to match the rates required by modern codes and their current use. As part of the study, we completed a code review and analysis of air handling systems and their respective air-change rates. These calculations revealed several air handlers which, either through a change in use or insufficient commissioning, were far over-supplying the code-required air changes to the space. In addition to excess fan, heating, and cooling energy, this also increased the required reheat energy. Identifying these locations as part of the retro-commissioning effort allowed the facility team to reduce fan speeds and their associated cooling, heating, and reheating loads. In one particularly significant case, an existing surgery air handler was able to have its airflow cut in half while still fulfilling the spaces health and sanitation requirements. This simple adjustment resulted in savings of approximately $25,000 per year.

HVAC System Speed

Most modern hospital HVAC systems are now designed with variable volume fan technology. This means they can speed up or slow down fans and cooling/heating as required to meet changing building loads. Often in a facility, the quick and easy way for a construction team to set up these HVAC systems is to pick an initial system speed that is substantially higher than required and use this higher fan speed to commission the system. While this may simplify the construction of HVAC systems, the end result often is HVAC systems with fans running harder than necessary to achieve building conditioning but cannot turn down fully as required to achieve optimal energy performance. In addition to poor system set up, at times deferred maintenance or construction activities within the facility can cause clogged filters, building intakes, or coils. These clogged portions of the HVAC system introduce unnecessary load which results in HVAC systems that need to run harder to produce the same amount of cooling.

These changes reduced the carbon footprint of this existing facility by over 95 metric tons per year. We surveyed the existing building systems to determine areas where HVAC system speeds had not been optimized.

Through this survey, several opportunities throughout this facility were identified and corrected which led to significant energy savings. In one case, an air handling system was identified in which the original fan speed was set nearly 30% higher than necessary. Adjusting the speed setting of this system saved the facility an estimated $7,500 per year. In addition to these savings, several maintenance projects and clogged air intakes and coils were identified which resulted in additional savings for the facility.

Scheduling Study

Modern HVAC control systems generally turn on when spaces are in use and then turn off or at least slow down when people leave for the day. This capability is referred to as ‘system scheduling’ and is a critical component of optimal energy performance. However, these schedules can often get muddied in a large health care facility that has been renovated and re-purposed over the years. As building uses change, sometimes the HVAC schedule no longer fits the needs of the space. As part of the retro-commissioning effort, each area of the building was reviewed with maintenance staff to compare how it was programmed to operate versus how each area was actually used.

In several instances, our study revealed HVAC systems that were programmed for patient care or 24/7 operations but now, housed administration areas or visitor spaces that were only occupied during business hours. In these instances, we worked with a building controls specialist to add additional schedule programming to ramp down or shut off the HVAC system entirely during unoccupied periods to greatly reduce airflow during off hours. In one instance, implementing this strategy saved the hospital place that had removed the scheduling feature from these units entirely. Re-instituting the proper scheduling of the three air handlers led to an annual energy savings of $58,000 per year. 

Steam Evaluation

Most aging healthcare facilities’ source of primary heating is steam. Large steam boiler systems are centrally located and pipe steam throughout the facility. Over the system life cycle they can suffer from poor energy performance through failing components. A key element of this piping system is called a steam trap. These devices remove excess moisture from the steam piping and are located throughout the facility. Over time, these steam traps will fall open, allowing valuable building steam to escape into the atmosphere. As a part of this project, a full steam trap survey was completed to determine if these devices were still operating as required. The survey discovered that over 30% of the steam traps in this existing facility had failed. Fixing these traps resulted in energy savings of over $22,000 per year.

Planning for the Future

In addition to surveying and identifying low-cost and no-cost changes for the facility, part of the retro-commissioning process was assisting the facility to prioritize future energy saving investments. The full survey of their facility included collecting data on the existing HVAC systems and establishing a rank for which systems were the greatest priority for replacement or upgrades to save additional energy dollars. In addition, the report identified specific areas for improvement and suggested energy projects along with their anticipated cost and savings. As a result, the facility now has a roadmap for the future to continue to improve its energy efficiency. 


At the end of the retro-commissioning process at BSMH Lourdes Hospital, over 30 major HVAC systems were evaluated, with over 27 low-cost and no-cost changes implemented along with helping the facility to develop a roadmap for future energy-saving projects. The process saved nearly 8% energy use in the first year of operation, taking their EUI from 252 KBTU/SF to 238 KBTU/SF. After reviewing utility cost data from the facility, these changes are projected to save the facility $181,000 in its first year. In addition, their environmental impact as a result of these changes reduced the carbon footprint of this existing facility by over 95 metric tons per year – the equivalent of taking an additional 20 cars off the road per year and savings in cooling energy were able to offset water use by nearly 672,000 gallons per year – the equivalent of an Olympic sized swimming pool a year.


Energy savings and a reduction of a health care facility’s energy use are not limited to the realm of new construction or major renovations – it is possible through retro-commissioning to achieve significant energy and cost reduction.

An easy place to start is benchmarking facilities and comparing the data to like facilities through EPA’s Energy Star Target Finder website. If your aging facility’s EUI is process is straightforward, it takes time and effort to achieve significant results. But it is possible to reduce energy use and retro-commissioning can be a helpful tool in the march toward a more cost-effective and sustainable future.

Matt Wade, PE, is a mechanical engineer at CMTA.

Jonathan Hunley, CHFM, is the director of infrastructure, Bon Secours Mercy Health. 

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