Don’t question commissioning when it comes to lighting controls
Commissioning and testing are as critical for lighting controls as they are for building management systems.
By Lindsey Fimek, PE, LEED AP BD+C, Primera Engineers Ltd., Chicago
Pop Quiz: What is the biggest heat load in a building that we can control? If you guessed lighting, you’re absolutely correct. To justify lighting controls as a value investment for a property, it’s crucial that lighting controls systems are calibrated, adjusted, programmed, and…
Can you guess the next word? If you said “commissioned,” you’re correct again!
Lighting controls are one of the last pieces installed in any building and the last to get programmed and commissioned. Many times the start-up and commissioning process can be rushed, leaving the lighting controls system and components in a functional but not optimal operation. The recently published ASHRAE 90.1-2010 energy code will require a third party to perform functional testing of the lighting controls to verify the performance meets or exceeds all documented performance criteria. This energy code is likely to be adopted quickly by state regulated energy codes and green initiative design criteria.
Functional testing and follow-up after start-up and commissioning are performed help ensure the designed energy savings are realized. If you’re nearing project completion, persuading the owner to adopt this practice will mean he’ll enjoy a return on investment on current projects rather than waiting for future renovations or new construction. Skipping the start-up and commission, however, can lead to an underperforming system, unused features, and a loss of energy savings.
After all, like many other moving parts in the MEP/FP discipline, you can’t just “build it and walk away,” expecting the system to function efficiently. Commissioning and testing are as critical for lighting controls as they are for building management systems.
Why you should never question commissioning
Most lighting controls equipment available today requires careful tuning once installed and should be tuned up again after installation. From the simplest stand-alone occupancy sensor to the most elaborate building-wide control system, all need some calibration. In a recent product discussion with an occupancy sensor manufacturer, we were informed that sensors have an automatic learning feature that takes about 1 to 2 weeks to capture the use of a room. “Auto-commissioning” sounds great, but there is a catch: if sensors are functioning prior to the final user occupancy, then the sensors will learn the wrong behavior. This causes the sensors to take even longer to adjust, leading to final user frustration, a fixed override of the system, and taking the sensors out of commission. By resetting the occupancy sensors just before the user arrives to the space, a normal cycle of auto learning can be achieved. Tiny nuances such as this example will be slightly different for every manufacturer, but one thing is for certain: it’s critical to have a trained professional involved in the final project start-up and programming to ensure the system is working at its highest level.
We typically design buildings for facilities with a long lifecycle and want all of the initial investments to pay back as they are designed. The energy savings gained by a fully functioning lighting controls system pays back so quickly that the start-up and commissioning should never be questioned. The additional expense of start-up and commissioning of lighting controls is only 6% to 7%, which is worth every penny when it allows 7%-13% of yearly energy cost savings. See the case study in the sidebar, comparing two buildings’ performance over one year and the money lost by not implementing a control method as simple as an automatic time schedule.
Figure 1: The lighting controls cost comparison illustrates that owners should get what they pay for—and accountability can help. Courtesy: Primera Engineers Ltd.
The question of responsibility
Whose responsibility is it to connect the owner, manufacturer, and commissioning agent? One could argue two sides of this coin. First, the owner should always make sure he is getting what he paid for by following up and asking questions. But sometimes owners are not aware of the resources available. They are accustomed to calling a local electrician who might not be familiar with one of the 10 different lighting controls manufacturers whose products could have been installed. At this stage, the owner likely needs the quickest solution to make the system or space function. Often times this means disabling the controls to make the space ready and usable immediately. In reality we should reconnect our contractors, manufacturer field technicians, and installers with the end user. Following up on the system performance and holding all parties to the construction specifications is in the best interest of the owner. The systems should function as designed, allowing the owner to get what he paid for: to save energy and earn some return on the investment.
Given the two examples of cost savings in the sidebar, it is evident that commissioning lighting controls can generate a very quick payback when systems are designed effectively. The practice of third-party functional testing for lighting controls outlined in ASHRAE 90.1-2010 should be adopted now. As lighting controls become more complex in response to tighter energy regulations, the added cost of controls can only be justified to an end user by the energy savings generated when the system works optimally.