BY SCOTT R. DRURY, PE, FBPE MEMBER
Let’s be honest, most people want to save a buck or two. While not everyone is concerned with saving energy, most people are very interested in saving on energy costs. This is the reason that some folks, like me, sometimes look around and wonder why every light in the house is on, including rooms that nobody is in. Then, there are those who keep the thermostat in their house set to 78°F, but set the thermostat in a hotel room to 55°F because they do not have to pay the energy bill.
Commercial and institutional building owners also want to reduce energy costs. This is not simply a question of having every building certified under a “green” certification program. In fact, many owners complain that their “sustainable certified” buildings use the most energy out of all their buildings.
The energy costs routinely paid by owners (whether school districts, universities, governments, etc.) sometimes prevent them from investing in other things they would like to improve. Sometimes it just takes money to save money. And, many owners do not always have the money to make this type of investment.
For years, there have been groups to help owners reduce their energy costs. One option is using “ESCO” (energy service companies) projects, where the ESCO fronts the money to the owner for energy improvement strategies and gets paid back with interest through the energy cost savings. Another option is retro-commissioning, which is typically used to improve the efficiency of the existing equipment and systems with minimal upgrades.
With either option, the strategies typically include changes to optimize how and when systems operate and to improve occupant comfort, if possible. Sometimes, the strategies even include adding, removing, or modifying system components. However, these strategies are not always designed and implemented under the direction of a Professional Engineer. In fact, many of these implemented strategies are performed without consulting the engineer who originally designed the system and without going through a permitting process, which would establish a new engineer of record and help ensure that changes are in compliance with all applicable codes. These changes can even put the original engineer of record at potential risk, if the process is not documented well.
Let’s face it… engineers are not necessarily experts in control systems. Similarly, experts in control systems are not necessarily engineers.
System controls are sometimes used to correct some engineering design issues, yet they can also create issues if not implemented per the design. There are many cases where the implemented controls do not meet the required design criteria because it was easier to provide the same controls as a previous project.
I do not mean to imply that an engineer’s design is perfect and that system control providers are being malicious in their implementation. On the contrary, my purpose is to establish this as a team effort to achieve the best results in the end.
Engineers typically design systems to meet the required codes and relevant engineering principles, which may include various safety requirements, limitations due to existing infrastructure, and specific user requirements. System control technicians interpret engineering design, often needing to read “between the lines” in order to get enough information to make the system work properly.
The system control technician does not always know “why,” and the engineer does not always know “how.” It is a team process to make this work properly.
The most energy efficient piece of equipment is one that is off. When operating, there are certain components or functions that use more energy than others. A lot of the energy-cost-saving strategies are based on limiting the amount of time that equipment is used and trying to identify ways to reduce energy and improve system performance when the equipment is operating.
Similar to how certain designs are not applicable to every building, not every energy cost savings strategy applies to every system. For instance:
- Resetting the supply air temperature from an air handling unit can prevent sub-cooling in the spaces and temporarily improve occupant comfort. But if not done correctly, this can cause mold in the duct systems and potential health risks to occupants.
- Disabling equipment in an old building when it is not occupied can definitely save energy but can also create a condition where the system cannot maintain acceptable temperature or relative humidity ranges within the building, causing damage to equipment and potential mold and health risks to occupants.
- Since dehumidifying outside air can be very expensive, especially in Florida, reducing the amount of fresh air introduced into the building can save a lot of energy costs or help improve equipment performance. But, if not coordinated with the associated exhaust systems, the building could be negatively pressurized, resulting in infiltration (again, leading to mold and health risks to occupants) or unsafe pressurization levels in buildings for hazardous exhaust containment or where the force to open a door is above the allowed threshold.
These are just a few examples that have actually occurred in buildings by implementing energy-cost-savings strategies without consulting the design engineer or going through a permitting process. Some of these modifications occurred after a building was verified to work properly by an independent commissioning provider; others were not. Some were even made without discussing the proposed strategies with the owner or user group, but simply under a contract to do whatever it takes to save energy costs.
The reason that I bring this to your attention is that in each of these cases, the engineers of record had no knowledge of the changes that were made after the fact. When the owners started having concerns over mold growth, potential health risks, uncomfortable space conditions, or safety issues, the engineers of record were blamed for the problems.
In order to preserve their reputations, in many cases, the engineers provided free services to help investigate and resolve the issues, only later to discover that the designs were modified after the fact in efforts to save energy costs. This not only could have affected their reputations and future work with the client, but could have resulted in someone filing a complaint against their engineering license.
Therefore, it is important for engineers to keep good records of everything associated with a project, which includes correspondence and reports of how systems are performing when the project is closed. This will help protect you against any undocumented changes made to the design after the fact. It is also recommended to discuss with owners how important it is to involve a Professional Engineer in the process of implementing energy cost savings strategies.
Scott R. Drury, PE, is a licensed Professional Engineer in Florida with expertise in both mechanical and fire protection engineering, and is a certified Commissioning Authority (CxA), Certified Firestop Inspector, and LEED Accredited Professional (LEED AP BD+C). He is the senior associate for H2Engineering Inc. with offices in Tallahassee and Gainesville, Fla. Mr. Drury began serving on the Board in February 2018 and is currently chair of the Fire Protection Rules Committee.