By Estatio Gutierrez, Ph.D., Optimization Engineering Manager
January 26, 2017
Research has been conducted around the topic of discomfort in the workplace and how it affects productivity. Stuffy, hot rooms make people distracted, while comfortable rooms equate to more socially engaged, constructive, more collaborative people —in other words, more productive.
It is the ability to monitor, analyze, and balance all of the critical factors involved in the conditioning of interior space for optimum human comfort that drives what we do at BuildingIQ. Our 5i platform is based on a five-pillar approach that begins with monitoring and data capture, and goes on to advanced modeling, predictive control, and expert human analysis, and client consultation.
In the end, our customers know comfort is delivered when their building’s tenants (occupants) are comfortable. This usually happens when the supply air temperature resides within a narrow comfort zone —between 71-75 °F in summer and a little lower in winter. And when the supply air is moving at just the right speed, and the return air has been refreshed, mixed with outside air, and conditioned to filter impurities and bring humidity into alignment. When all of that is in balance, the tenant can put his/her comfort concerns aside and focus on the people around them and the task at hand.
A Real Case Scenario
One of our recent clients provides a great example of how comfort can be improved by monitoring the performance of a commercial office building, and using predictive energy software to interact with the BMS. One of the first tasks was to help our client identify and resolve technical and mechanical issues that hindered the ability of the HVAC to deliver balanced comfort to the tenant.
Our client’s property is a medium sized, ten-story office building with a air-handling units (AHU) operating independently for each floor. During the first step of the process, something we refer to as Learning Mode, BuildingIQ’s platform connects to the BMS to learn the thermodynamic behavior of the building —how it lives and breathes. For the first month, the system gathers data on the building’s response to external conditions (temperature, humidity), as well as internal conditions (occupancy patterns, tenant equipment, specialty spaces, etc.) Through iterative prediction and adjustment, using closed loop optimization, BuildingIQ platform refines its understanding of the building and HVAC performance. Based on this information, it can then model and predict future energy needs for the building. The goal is to optimize tenant comfort, energy consumption, and cost.
The month-long learning process, for this client, revealed a number of technical issues adversely affecting the operation of the building’s HVAC system. Our team met with our client with specific diagnosis based on anomalies found in the energy data, and provided recommendations for improvement. This information we provided will allow our client to have its own engineering staff rectify mechanical problems.
During the second month, we moved into the second stage, where the BuildingIQ platform started controlling the BMS. It now provides optimized supply air temperature and supply air pressure setpoints to the BMS, which in turn responds in accordance with pre-programmed instructions on everything from damper operation to pre-cooling schedule. This is an ongoing process that involves isolating and resolving issues in an interactive, consultative manner to enhance HVAC performance.
Currently, BuildingIQ’s control is limited to the AHU for each of the ten floors. Tenant comfort requires a much more granular level of feedback and space conditioning for distinct spaces and offices within and on each floor. It is likely that the onsite facilities team will keep this under their control —involving direct contact with their tenants— within their own purview. That said, our team is available 24/7 to help them —behind the scenes— troubleshooting specific technical problems with their tenants.
Some of the specific issues we were able to identify during Learning Mode included:
- Supply air temperature for AHU-1 oscillating: Supply air temperature was oscillating by 10°F, unnecessarily cooling the space. The chilled water valve was “hunting” —opening and closing dramatically. This suggests a major energy leak. Equipment needs to be tuned.
- Supply air pressure for AHU-1 inadequate: Supply air pressure consistently failed to meet its setpoint when outside air temperature was above 65° See Figure 1. VAV was starved for more cool air than the AHU could provide, forcing fan speed to maximum levels. It could be that the fans are undersized for the VAV requirements.
- Return air sensor in AHU-9 needs calibration: The return air for this zone frequently fluctuated by 6°F in a short period of time. Responsiveness of the sensor should be checked and possibly recalibrated.
- Outside air dampers operation hindering fresh air delivery: Throughout the building, dampers were not operating properly. Dampers are the primary means of ensuring continuous flow of fresh air. We found that the dampers were completely closed during occupancy hours, on six of the ten floors, and operating erratically. The outside air damper sequence should be revised. Mechanical issues with the dampers may be a source of the problems.
- Equipment operation out of phase within scheduled hours: Equipment was not being turned on according to the pre-planned schedule. For nine days in the Learning Mode period, fans were coming on at midnight, thereafter at 3:00am. There is no reason equipment should be running in the middle of the night unless the zone contains a data center. Our client was unaware of this scheduling lapse.
Figure 1 – Air Pressure Unable to Track its Setpoint in AHU-1. For the month of October 2016, the graph overlays outside air temperature (dark blue), supply air pressure (light blue), and the supply air temperature setpoint (orange)
Many issues were resolved once the BuildingIQ platform took control and sent optimized setpoints to the BMS. Others required on-site inspection, mechanical repairs, and upgrades by our client’s engineering staff.
We want to think of our relationship with our clients as a journey and partnership. We both are trying to make the building a success, always having the tenants’ comfort in the forefront of our thinking. Problem solving is tightly integrated. A close working relationship allows us to leverage our diverse talents and experiences, and to remind each other that our ultimate customer is the tenant whose ‘human thermostat’ instinctively understands the finely-tuned balance inside the comfort zone.