What is a Photometric Lighting Plan?

One of the biggest challenges of buying new lighting or upgrading to LED lighting from existing fixtures, is anticipating how your new lights will look and function in your space. Luckily, there is a solution. A Photometric Lighting Plan is a software report of LED Lights placed within an indoor or outdoor area. Using a special lighting software program, you can create a simulation of an indoor room or an outdoor area. The software is capable of importing layouts, cad diagrams and even scaled google maps of outdoor areas – particularly interesting when created lighting plans for outdoor sport facilities.

The software can place the fixtures inside the plan at specific location and heights. They can be oriented and aimed. The lighting plan calculates foot-candle light levels, shows how balanced the light is,  and provides a comprehensive printable pdf report.

Lighting Terms 101

The cheat sheet for everything you need to know in order to be an expert on your lighting. 

Lumen –  A lumen is a unit of light. By itself it’s useless, but it becomes useful when it defines the collective lumens produced by 1 fixture or bulb. It is the amount of visible light that a fixture emits.

Foot Candle –  A foot-candle is a measurement of light at a specific location, and 1 to many lights can contribute to the specific foot candle reading at that location. Foot candles (or its equivalent LUX) are the requirement that most are looking for when they describe a light level for a project, facility, or location.

Beam Angle -The beam angle of a lamp is the angle at which the light is distributed or emitted. This can be done with additional optics, or as is the case with LEDs, by engineering the light in a specific way. LEDs have an extremely large range of available beam angles. 

How to Read a Photometric Lighting Analysis

A lighting plan won’t provide you any benefit unless you know how to read it.

If this will be your first LED Lighting Supply photometric plan, it may seem like a bunch of complex figures and statistics. However, it isn’t as difficult to understand as you might think.

Refer to the lighting plan for the basketball gymnasium on the right as we share some terms to familiarize yourself with how these plans work.

Indoor Basketball Court Lighting Calculation

1. Foot Candle Measurements

A foot-candle represents the amount of light that reaches a surface area, and it’s measured in lumens per square foot. In the above plan, you’ll see that there are several reading points within the lighting plan. These represent the foot candle readings for each specific point. And if you’d rather look at the layout in meters, the software can also calculate lux instead of foot-candles.

Lighting Plan Footcandles

2. The Fixtures

The light fixtures, arguably the most important thing on a photometric lighting plan, are shown as red dots. The dots show where the light fixtures should be located to give the optimal lighting coverage.

Fixtures can be swapped out and plans recalculated to find ideal lighting for the specific environments and area.

Lighting Plan Fixture

3. The Schedule

This is an extremely important part of a lighting plan that is often overlooked. The schedule is found at the bottom left of your lighting plan, and it goes into further detail about the types of fixtures recommended in the lighting plan.

Lighting Plan Schedule

4. The Calculation

This is where some of the most valuable information in the lighting plan is found. This section is found on the right of the schedule, and identifies the light levels and distribution ratios of the fixtures outlined in the schedule. It provides some useful information about the foot candles measurements in the plan, including the average, maximum, and minimum. These numbers are often used to ensure that projects are in accordance with building codes.

Out of these numbers, the average is the most significant. This is the ideal or “target” foot candle reading for the entire project. We can then calculate an Average/Minimum foot candle reading, which shows us how much the dimmest spot differs from the average.

The Max/Min ratios is also important, as it shows the overall lighting distribution for the space. Building codes are made so that buildings have an even distribution, which helps with visual comfort and safety.

By familiarizing yourself with the above terms, you’ll be able to effectively read your photometric lighting plan, and design a lighting layout that works well for your specific facility.

However, even if you feel comfortable reading a photometric lighting layout, questions may still arise. If you have any issues, questions, or concerns, feel free to reach out to one of our lighting specialists.

Lighting Plan Calc

The Difference A Photometric Lighting Analysis Makes

BEFORE

AFTER

Inadequate Light Levels or Spotty Distribution

Bad distribution and poor lighting levels are a major issue in the lighting industry. Many facility managers who are looking to convert to LED lighting end up buying products online without going through a proper analysis. They make assumptions about what should work in their space, and encounter problems once they have bought and installed the new lighting. We end up hearing the following complaints often:

It’s too bright.

It’s not bright enough.

The light is not uniform.

The light is too bright beneath the fixture.

This is why we always suggest a photometric lighting plan. Otherwise there is no sure way to know what your outcome will be. Even though some suppliers will suggest that all many fixtures aren’t all that different from each other – we know that couldn’t be farther from the truth. 

The only way to accurately predict how your lights will look is to have an in-depth understanding of how light behaves in large spaces. But unless you are a lighting engineer, this information is out of your wheelhouse. And, that’s where the photometric lighting plan comes in. A photometric lighting plan takes everything into account and does the math for you so that you can make an informed lighting purchase, whether or not you’re a lighting engineer. 

The issue with buying lighting fixtures online is that you can’t be 100% sure of what you are buying. A lot of time manufacturers will sell old inventory with outdated features and old chipsets. It may seem like a bargain, but you’ll quickly realize that you’ve made a huge mistake.

 

Understanding Your Current Light Levels

You can’t understand where you’re going if you don’t understand where you’ve been. Alright, that’s not exactly how the saying goes, but it does still apply here. In order to understand light levels let’s introduce the concept of foot candles or lux. They are basically the same thing: light measurements.

You can take light readings using a handheld light meter or an app on your smartphone. A free light meter app gives some reliable basic readings, but if you have a complex light environment or want to be completely sure, we recommend investing in a light meter.

For example, you may have a production facility and are looking to upgrade to LED Shop Lights. A good process would be to install a light meter app on your phone and use it to take several readings around your facility. Go under a light, go-between lights, go into the center of the space, go to the edge, and take readings.

From this, you will get a good idea of how your current lighting is performing, and your current light levels. But you can also use this method to determine things like:

Are my light levels OK, too bright or too dim?

Are my light levels pretty uniform and evenly distributed?

Would I like to improve the light levels, or are things OK

Indoor Factory Lighting Plan Example

In this light plan, the customer’s current lighting was averaging around 12-foot candles. They approached LED Lighting Supply for an upgrade to LED, but like most large customers, wanted to take the first step and perform a light analysis.

They wanted more light, they wanted to save energy, and they were tired of changing out bulbs and ballasts.

The customer provided LED Lighting Supply with a CAD file (.dwg file) and we imported it into our software.

We modeled 1 area, replacing their HID lighting with a combination of 120 Watt and 200 Watt LED High Bays.

In the main work area, we increased their foot candles from 12 to 41! Average Min Ratio of 2.31 indicates uniform light levels throughout the space.

Outdoor Street Lighting Plan Example

This is an example of a DOT application, replacing 1500 Watt High-Pressure Sodium lights with 600 Watt LED High Mast Lights with 150 degree distribution optics.

ISO-lines (color lines on the plan) represent foot candle layers or transitions, with the red-line representing the location where the light drops below 0.6 foot-candles.

LED Lighting Supply can use scaled images from Google Maps to create an outdoor photometric plan.

 Photometric studies allow customers to see how the lights will perform before having to commit, and allows for the lights lumens and optics to be adjusted to meet the specifications or desired amount.

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Frequently
Asked
Questions

What is a photometric plan?

A photometric plan is a visual way to display how a new lighting solution will illuminate an indoor or outdoor area. This is done using photometric software which creates a simulation of the physical space using imported layouts. The output of a photometric plan gives detailed calculations of foot candle readings throughout your space.

How is a Photometric Plan made?

Photometrics plans are created with specialized software. This software uses  existing layouts and CAD designs, then lighting specialists input any features that aren’t included. Outdoor photometric plans can even use scaled images from Google Maps. Then, the software does the rest. 

How do you read a lighting plan?

You read a photometric lighting plan by referring to individual foot candle measurements for each lighting fixture throughout the space. You can also refer to the Calculation section where summary information and ratios are provided. These give you a “big picture” idea of how lighting is distributed. 

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