Consumption Concerns: Use ASHRAE Guidelines
This step does not necessarily pull out lighting energy use. To determine if lighting consumption is high, managers can break down of total energy use into end-use components as detailed in the ASHRAE applications handbook.
Luckily, since lighting power consumption does not change based on the season, managers should be able to estimate lighting power consumption regardless of the season. To perform an ASHRAE Level I Energy Audit of the lighting and associated controls, managers can focus on the following items:
Walkthrough. Perform a walkthrough of the building, focusing on the lighting and associated controls as they relate to different areas of the building. At the same time, determine if any significant upgrades have taken place.
Outliers. Search for atypical situations and deficiencies that could result in wasted energy use, such as broken occupancy sensors or light switches, excessive task lighting, and bulbs removed by occupants. In many instances, occupants modify their spaces with a makeshift solution that meets their needs but might affect other occupants.
Function analysis. Perform a space function analysis to determine if space use has changed and if this has any effect on operational efficiency. Are all similar spaces, such as conference rooms and private offices, controlled the same? In older buildings, it is not uncommon to see a space's function change dramatically compared to its original intent with no change to the spaces operational characteristics.
Breakdown. Estimate lighting energy consumption via bulb or fixture counts, power consumption and estimated runtime. From a cost-analysis perspective, this step will help determine the amount of energy to be saved by low-cost and capital-intensive measures, as well as ones.
Cost. Focus on low-cost and no-cost measures to the facility, as well as they way different operations might affect annual savings. Installing a lighting timer that ensures building lights are off during unoccupied hours ensures no energy is wasted when the building is unoccupied.
Big tickets. Determine potential capital-intensive improvements, which provide longer-term savings but require larger changes in the facility and its operations.
Tactics For Savings
While considering major upgrades to curtail lighting costs, it can be just as important to focus on daily routines. Encouraging and reinforcing occupants' positive habits, such as turning off lights when leaving a room and opening window shades to increase sunlight, can result in significant energy savings.
When possible, managers can consider submetering tenant electricity consumption and passing these costs to the tenants, which can provide almost immediate changes in operational behavior. Multiple studies indicate that energy use can drop by up to 50 percent when tenants are fiscally responsible for their energy consumption.
In the retrocommissioning process, a handful of diagnostic tools can help front-line technicians identify light levels and power consumption. In facilities with dedicated lighting panels, technicians can use a clamp-on current sensing transformer and associated data logger to trend a building's actual lighting consumption and more accurately assess savings.
This information might present anomalies in the expected power consumption versus the actual use — for example, due to lights left on or improper scheduling. By using an inexpensive light meter or light-level trending device, technicians can determine areas that are overlit or underlit based on their function, as well as whether sunlight might be a viable option via photo-cell operated window shades.