Aug 102009
 

A couple posts ago I raised a point about buildings being smarter than the owners. So what is the solution? How can an owner or manager get control of their building and get the operations and maintenance running in an optimal budget?

Rebecca Ellis (Questions & Solutions Engineering, Inc) has written some interesting articles on the use of Trend Logs for Engineered Systems Magazine. In the articles she talks about monitoring critical building parameters (temperature, Internal Air Quality, Humidity, pressurization, etc) along with energy consumption. Ellis suggests creating a list, prioritized based on the systems benefit. “Each trend log should consist of points such as temperatures, valve positions, damper positions, set-points, motor speeds, etc., that can illustrate the reaction of inter-related control parameters all on one graph. I recommend keeping the number of points on each graph to no more than six to eight, if possible. That may mean splitting a system into separate temperature control, humidity control, pressure control, etc., trend.” She points out it is better to start small than to bite off too much.

The secret to monitoring your building is knowing what to expect. For each set of graphs, there should be a corresponding baseline graph of expected values for each mode or season of operation. An instruction sheet outlining steps to take if the recorded values don’t match the baseline values  give the Operations and Maintenance staff guidance to bringing the system back into an optimal state. However, she also points out the baseline should not be seen as that optimal state but as a minimum performance standard. The Operations staff should strive to improve the system and match the changing needs of the building and its occupants. Ellis points out three areas the staff should look at:

  • Identify operational problems before they become performance problems;
  • Identify inefficiencies before energy use and costs escalate; and
  • Track energy consumption and measure the impact of conservation measures implemented by the O&M staff.

Ellis points out this is not a trivial undertaking and ideally would be done on a monthly basis with a small group of trained operations specialists. She says the process has been computerized and can continuously analyze the data but is only meaningful when used with off-the-shelf  system components.

There are huge savings to optimizing your building control system. In my option it is well worth the time and will yield energy savings, cost savings, and better comfort for your occupants. I think it also makes your operations staff feel like they’re running the building and not the building running them.

References

Trend Log For Ongoing Monitoring and Optimization by Rebecca Ellis in the August 2009 edition of Engineered Systems – Picking your points and selecting your scope to avoid getting overwhelmed.

Trend Log Analysis II by Rebecca Ellis in the July 2009 edition of Engineered Systems – In which a mysterious five-degree difference is a $4,400/yr anomaly. “In the best of all worlds, these types of trend logs would be collected and analyzed up to three times during the first year of operation, depending on the local climate: 1) during the winter; 2) during the summer; or 3) during a transition period, either spring or fall.”

Trend Log Analysis by Rebecca Ellis in the June 2009 edition of Engineered Systems – How to spot performance problems hidden beneath the surface?  “Most building systems do not experience drastic changes in load conditions during normal operations. Therefore, the Functional Performance Testing (FPT) process does not allow observation of the systems under normal operating conditions and load fluctuations. The use of trend logs to validate extended operation of some or all of the systems is a valuable process to supplement field functional testing.”