In our previous issue, we touched on some ways to improve the available light in high bay areas without adding new fixtures. Now let’s look at how to reduce energy consumption in those areas.
First, look up the efficiency data on the existing fixtures, then compare what you find to the efficiency data on possible replacement fixtures. If there’s enough difference, a replacement will be cost-effective.
Many people calculate the payback period, but if you’re trying to convince upper management to spend money you need to speak in their language. Managers want to see an ROI calculation, and finance departments want to see Internal Rate of Return. You’ll need to provide both figures. Microsoft Excel and financial calculators have an IRR tool.
Typically, projections of cost-savings are overly optimistic and the projected savings never materialize. To avoid having your numbers dismissed out of hand due to “rosy projection fatigue,” apply the “smell test.” If they seem too good to be true, they probably are. Check the assumptions that underly the calculations; this is typically where the errors come from.
While a direct one-for-one fixture replacement with newer, more energy-efficient units could produce significant energy savings, don’t limit your thinking to that one upgrade. Do a lighting survey to assess the lighting fixture layout; you might use fewer units.
Also look at the branch circuits. Running new conductors could produce significant savings from voltage drop improvements alone.