3 Steps to Savings
Armed with a concrete goal and the right tools, you’re now ready to start the audit. A truly comprehensive walkthrough should cover these areas:
- Gather data. This step informs all others. Make a note of every lamp and fixture in every space, documenting important characteristics like:
• Type and age of lamp
• Type and age of fixture
• Ballasts used (if applicable)
• Location in building (including the name and function of the space)
• What controls are present (if any)
As you cover each room, consider taking a photo of every fixture type to aid analysis later, Bridges recommends. Also review recent electric bills to determine the cost of electricity – this will help you estimate the ROI of potential projects.
- Examine occupant needs. Determine the typical tasks of people working in the space, as well as how frequently spaces are typically used and for how long. The Illuminating Engineering Society (IES) issues recommended footcandle levels to ensure visual acuity and comfort for different tasks and age groups.
“One size doesn’t fit all for lighting design – not even close. What works for someone in a research lab probably won’t work in a space where people are designing with CAD on computers,” Markowitz says. “You’ve got to plan ahead and look at recommended practices for lighting the specific type of space in every case.”
Don’t neglect to measure the average traffic as well. Where do building occupants tend to congregate? Which spaces are empty more often than not? Existing building schedules can help shed light on additional sources of savings.
“Let’s say your people spend very little time in their offices because most of their time is spent in common areas for meetings. This would produce a high vacancy rate, which presents an opportunity for an occupancy sensor,” explains Bernie Erickson, division manager for Facility Solutions Group. “Do you leave the lights on until the cleaning crew gets there? There’s an opportunity to do some load shedding. There are loggers you can place in offices that will track vacancy and validate those savings, or you can use rule-of-thumb industry generalizations that you can plug in for the time being and get more exact data later.”
- Assess the space. Before starting the project, take stock of the tasks and activities in every space you’re evaluating. This impacts recommended lighting levels, visual comfort, and color requirements, explains Markowitz.
“Let’s say you have a machine shop with exposed egg-crate T12 fluorescent fixtures, and the fixture and lamps are covered with dirt from years of work in that space. The amount of light coming from it is compromised due to light depreciation from the dirt. In hindsight, that probably wasn’t the right fixture to put in service,” Markowitz says.
Renovation plans will affect lighting performance as well.
“If you’re going to repaint the area, consider what you’ll use, because the paint color will change the amount of light in the room,” Markowitz says. “The reflectance of the floor, walls, and ceiling all impact the light levels measured at the work surface. Lighter colors can result in a design with fewer fixtures or lower wattages.”