How many lights do I need?
For lighting projects, a common question we’re asked regularly is how many lights will be needed - and sometimes of course, the obligatory “are you sure?” that follows! Fortunately, the recommendations we make are based on some very well-founded processes, and it really isn’t rocket science; it just takes the right tools, knowledge, and experience. Today we are sharing with you the process.
The straightforward retrofit
Sometimes, for retrofit projects, we want to keep everything as similar to the current set-up as possible; in this case, it’s a simple matter of maintaining the current lumens (read about lumens here) per lighting fixture.
For example: Michel has 20 400W metal halide high bay fixtures in his warehouse, and he wants to convert them to LED to save on energy. He wants to install the new high bay fixtures in the same locations as they are in now, and he is very happy with the way the light looks now. Each high bay fixture emits 29000 lumens. We would recommend to Michel 20 of our 200W LED high bay fixture, which emits exactly 29000 lumens each, which would maintain the same look and feel and consume less energy.
The power of the lighting simulation
Sometimes, it is not as straightforward. The customer may wish to change the layout of his/her lighting fixtures, perhaps for aesthetic reasons, or because they are doing renovations alongside the lighting retrofit and the mounting options become expanded or more limited. The customer may want more light than now, or less light. The customer may be changing the type of lighting entirely, or it is a new-build with no past lighting to base the decision on. This is when it is very valuable to contact a lighting specialist so they may conduct a lighting simulation.
Scenario: Jamie wants to retrofit his warehouse lighting. In general, he thinks the old lighting job was poorly done; the high bay fixtures were too dim in some areas, and too bright in others. The fixtures themselves don’t look very appealing and the lights are not the same color temperatures (read about color temperatures here) either. He’s not sure how many lumens his current high bay fixtures emit.
To get the right levels of light in the different parts of his warehouse, it is important to understand a few industry concepts.
Footcandle: Lumens per square foot (read about lumens here).
Working plane: the height off the floor at which tasks are completed. Defining the working plane ensures we are measuring the light where it matters.
The goal of the lighting simulation is to ensure we get the appropriate brightness (in footcandles) at the working plane, such that we end up with just the right type and number of lighting fixtures!
The first step is to decide how many footcandles you need, either based on current lighting levels or industry recommended light levels. To find the current brightness, we can use a lux meter to measure the footcandles at the working plane and adjust this to be brighter, the same, or less bright as required. Otherwise, we can refer to the rough industry recommendations (read more here).
Then, using a lighting simulator, a lighting specialist will input relevant details, such as details of the light fixtures, size of the room, height of the ceiling, and height of hanging the light fixture. The result is a full report that shows the amount of light the set up will emit at every point of the room, such as the examples shown, done by Arani. From here, it is a matter of changing the lighting fixtures or the number of lighting fixtures until the desired result is achieved.
More detailed information about lighting simulation reports will be available here soon!
To contact an experienced lighting specialist, click here.