by David Lee
Many new buildings are focusing on sustainability, with words words like “green” and “eco-friendly” gaining traction with public opinion. We find ourselves often enamored with these marketable, energy-efficient new buildings and lose sight of the aging buildings that exist all around us. Considering that the majority of buildings we work, live, and play in are older, we should instead be focused on improving their performance. As buildings and systems age they degrade, malfunction, fall out of specification, or even change use. The effect of this performance degradation is poor thermal comfort, poor air quality, and wasted energy.
Retrocommissioning is the process of surveying, adjusting, and fixing mechanical, electrical, and plumbing systems in a building. This process not only helps restore systems to meet their operational intent, but assists owners and operators to make informed decisions on how they can optimize systems for their current needs. In some applications, the observed performance issues pose little more than a nuisance; however, in others it may have a major impact on the environmental conditions and overall energy landscape.
Healthcare is one of the sectors that can benefit greatly from retrocommissioning practices. Poor thermal comfort and poor air quality can seriously impact the quality of patient care at a hospital. Hospitals use up a significant amount of energy not only because of the research that they do, but because of the significant amount of air that they must condition. AIA ventilation guidelines for hospitals require 6 air changes per hour for most normal space types and between 12 and 25 air changes for specialty services and operating rooms, airflow that must be provided at all times. Compare that to a typical office which may require the equivalent flow of 4 air changes per hour at peak conditions, and you can already start to see a large difference in energy usage.
According to “Operations and Maintenance Benchmarks for Health Care Facilities Report,” published by IFMA in 2010, 49% of hospitals surveyed consist of multiple buildings, 44% are over 30 years old, and 75% have a central plant. What does this tell us about the hospital landscape in general?
First, it tells us that hospitals are constantly growing and constantly trying to accommodate the increasing demand for quality care. What once was carried out in a single building has undergone multiple expansions and renovations. Having undergone many changes, sometimes the buildings may not be consistent with existing campus buildings and installed infrastructure. Controls, building condition, or even design intent for the HVAC systems may be different or may even have changed since they were installed.
Second, it tells us that many of these hospitals are old. As buildings and systems age, performance degrades, dampers slip, valves start to stick, and sensors fall out of calibration. These issues contribute to systems that don’t perform properly and potentially waste energy.
Finally, it also indicates that the majority of hospitals have a central plant. ASHRAE-recommended service life for most large central plant equipment is between 20 and 25 years. If original equipment remains, chances are the facility can realize efficiency improvements with new equipment. Additionally, substantial controls improvements may be available since equipment was installed. These things combined will save energy for every BTU of energy generated for use across the hospital.
Hospitals use a large amount of energy, and there is a significant opportunity to use retrocommissioning to save cost and energy due to many hospitals’ age, size, and sometimes segmented infrastructure. The good news is you don’t have to be a major energy user to benefit from the retrocommissioning process. Retrocommissioning will typically save 10% to 15% for older commercial buildings in their energy costs. This means that whether you are a large energy user or a small energy user, you can benefit from taking a second look at your facility.
David Lee, PE, LEED AP BD&C, is an energy engineer at Vanderweil Engineers in Boston.