It’s said that humans are the biggest weakness in security systems. Similarly, outside air dampers may be the biggest weakness in HVAC energy efficiency projects.
The number one item on the National Renewable Energy Lab’s energy optimization checklist for commercial buildings seems to be pretty basic: Verify Proper Operation of Air Dampers.
Yet, in many of our implementations, it’s the air dampers that become the hitch in realizing returns. When our project manager goes in to do a site survey before the HLR is configured for installation, we always check the dampers.
We find a lot of variability in capability and condition. Sometimes, it's just mechanical: the nuts and bolts and hinges have rusted out, or loosened due to humidity or sea air- either way the damper doesn’t respond accurately to commands to open or close. Sometimes they open, but they don’t have full range of motion. Sometimes it’s a motor on the damper that doesn’t work. Or it’s located in a way that ventilation for a kitchen or a lab is tied inappropriately to office space ventilation. Or maybe the building is just old, and the dampers are hard to get to.
We are seeing some equipment makers, such as Honeywell, develop damper fault detection systems, that periodically test the dampers. If a damper fault is determined, these systems will send alerts indicative of a detected damper fault. But while these are being rolled out, testing the dampers is manual.
In a HLR deployment, our site project manager will help by checking the functionality and extent of wear of the damper mechanical systems and motor drive by sending out control signals at varying levels (open 10%, open 50%, open all the way, close to 30%, etc), and visually confirming that they are adjusting correctly in response to signals.
To get the most out of you HLR energy efficiency project, the project lead works with customers take steps to insure that all dampers are operating correctly. Baseline energy measurements are taken at the time of the site survey, after damper repair, and again after the HLR is installed and running.
Repairs rarely take long, but they make a big difference!
Note: if you only have fixed outdoor air dampers, then modulating damper actuators will need to be installed to allow for changes in outside airflow rates to get energy efficiency improvements.