By Kevin Player
The Domino Effect in Building Systems:
Small Changes, Big Results
When it comes to managing commercial building systems, it’s often the smallest details that make the biggest difference. An excellent example of this principle in action involves a recent project where we were working with a Laboratory Exhaust Fan System.
Spotting the Problem
During the project, we encountered a seemingly minor oversight — a 14" x 10" exhaust duct. This small detail, however, had significant consequences. The airflow for the duct wasn't listed on the plans, and the TAB contractor didn't balance it. As a result, it was left fully open, leading to an approximate airflow of 2,000 cubic feet per minute (cfm), which caused two significant issues.
Supply Short-Circuiting: Given the location of the supply air registers, the supply air was short-circuiting into the exhaust. This was exacerbated by the fact that the exhaust flow rate was nearly five times higher than the maximum supply airflows (200 cfm per register).
Overactive Exhaust Fan: The exhaust fan was running at a higher speed than necessary. There was no requirement for this storage space to be negatively pressurized, and the exhaust air should have been balanced to approximately 400 cfm based on the max supply airflow of 200 cfm per register.
These issues posed a threat to the system’s overall efficiency and functionality. If all laboratory hoods were ever in use at the same time, the airflow would be insufficient, given this exhaust register was unbalanced at approximately 2,000 cfm.
Implementing the Solution
To rectify this situation, we implemented two straightforward yet highly effective solutions.
Adjusting the Balancing Damper: We completely closed down the balancing damper. This adjustment still allowed for an exhaust of about 400 cfm, a significant reduction from the initial 2,000 cfm.
Redirecting Supply Registers: We adjusted the louvers on the supply registers to point downward, effectively preventing the short-circuiting of supply air into the exhaust.
Experiencing the Results
After making these small but impactful adjustments, the benefits were immediately evident:
Energy Efficiency: The normal operating speed of the exhaust fan was reduced by approximately 5%. This adjustment resulted in significant energy savings.
Improved Temperature Regulation: The storage space could maintain a more consistent room temperature without requiring excessive reheat. This was due to the prevention of stratifying and short-circuiting of the supply air in heating mode, which also contributed to further energy savings.
This project underscores the importance of meticulous attention to every detail, no matter how small it may seem. Through understanding and addressing the interactions between various building systems, we can enhance building performance, increase energy efficiency, and create a more sustainable future.
About Kevin Player
Kevin Player is a dynamic leader and the driving force behind the commissioning and Measurement & Verification (M&V) programs at Millig Design Build. As the Director of Project Performance, he spearheads these initiatives on a national scale, ensuring optimal project outcomes across the organization. With an impressive 15-year track record in testing, verifying, and troubleshooting electronic and HVAC systems, Kevin possesses a deep understanding of the intricacies involved in achieving peak performance and energy efficiency.
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