Everyone knows there is a huge push going on to optimize building performance. Building owners may wish to have a “green” and efficient building for environmental or financial reasons, but, either way, our industry has the knowledge, skills, and technology to create the better-performing buildings they desire.
After a building has been optimized, however, proper operations and maintenance (O&M) becomes the tool that will enable it to sustain its best performance. As might be expected, as building systems become more efficient and more tightly controlled, they also become more complex. In turn, so does O&M. Therefore, this column assumes that everyone understands the importance of general maintenance of equipment to maximize its lifespan, optimize efficiency, and minimize operating costs. In green buildings, however, it often is necessary to go beyond the proverbial “boxes.”
Establish a Baseline
When assessing an existing facility for a preventive-maintenance (PM) program, it is important to understand the building’s current energy consumption. We utilize a database of similar buildings along with the past year’s utility bills. If a full year of bills is not available, filling in the missing bills with construction-period bills will suffice. We use the Environmental Protection Agency’s (EPA’s) ENERGY STAR Portfolio Manager, which is an easy-to-use third-party tool that helps us identify a building’s “energy intensity,” or total overall energy use expressed in British thermal units per square foot per year.
We use Portfolio Manager to establish a building’s energy-use baseline, compare the building to similar buildings, and develop an energy initiative. This helps us determine what steps we need to take in a building. We must know the baseline to develop the best possible O&M program. If a building’s energy consumption is on the lower end of the scale when compared with similar buildings, the focus can be on basic PM tasks. If energy consumption is at the high end for buildings of its mechanical type, we know we need to look at other items along with PM tasks.
Maximize the Value of Controls
Once a baseline has been established, the next crucial element in ensuring peak building performance is the building-automation system (BAS). The BAS is the heart of a continuous optimization process.
The BAS allows monitoring of building trends that can indicate and help identify issues. For example, reviewing the historical trends from the weekend, when a building is shut down, may reveal that in 50 rooms the temperature drops at a rate of 1°F every 8 hours, while in 10 rooms the temperature drops at a rate of 1°F every one hour. Because the equipment is off at the time, the cause of the discrepancy in those 10 rooms is likely the building envelope. Likewise, if monitoring the BAS in the morning reveals that most rooms are warming at a rate of 1°F per hour but others are warming by 1°F every four hours, the cause might be an envelope issue, but it also may be an equipment issue, such as improper coil sizing, a dirty coil, or an airflow problem. A BAS can be used not only for optimization, but for maintenance and troubleshooting. By keeping utility bills current in Portfolio Manager, we are able to track the impact of any changes made to a BAS.
Of course, the data received for analysis will be only as good as the BAS that provides it, so the system’s sensors should be calibrated regularly, and the building should be periodically run through a sequence of operation to ensure the equipment is functioning in the way it is intended.
If a building does not have individual gas and electric meters, submeters should be added. Not only are submeters helpful in determining energy-conservation strategies, they are needed if the owner wants to pursue ENERGY STAR certification in the future. Connecting submeters to a BAS allows monitoring of energy consumption based on building load and can provide notifications of deviations from desired performance.
Comfort and Energy Must Walk Hand-in-Hand
Finally, do not forget that a major part of O&M is occupant comfort. The cost per square foot per year of a building’s human resources can be 100 times that of the energy costs for the same square footage of floor space. Be sure not to implement changes that reduce energy consumption at the expense of occupant productivity. A 10-percent savings in utility costs may save a building owner 20 cents per square foot. But if the energy improvements cause occupant discomfort that results in a 10-percent reduction in productivity, the cost to the owner in terms of lost productivity can be $20 per square foot. Occupant comfort must go hand-in-hand with energy performance for a building to be truly successful.
James Workman is a service operations manager for CCG Automation, an authorized Automated Logic dealer. He can be reached at jworkman@ccgautomation.com.