How To Create A Photometric Plan

Question

What is dark sky compliance?

The development of photometric lighting study began in the early 90's. The need for photometry paralleled the dynamic technological changes and the competition in the lighting industry. It was not until the IES was formed that the photometric studies were properly archived and the development of photometric practice that resulted.

Definitions of some key terms

Photometry - Photometry comes from the Greek word "photo" which means light. Photometry is the study and measurement of light. In modern photometry sciences, the radiant power of each wavelength is weighted and determined by a luminosity function which models humans' sensitivity to brightness. Today we call the study of light Photometrics.
Lumen - The photometric study involves determination of the luminous flux and Lumen is the SI unit of that luminous flux. In simple terms it is the measure of light output. Getting used to lumens is a big change from being used to '60 watt equivalent' in incandescent terms. That bulb has 800 lumens. Now we need to understand lumens like we understand miles. I want about 1200 lumens for my living room lamp. it will take awhile, but we'll get there. If you want to get scientific abiout it, ; is equal to the amount of light emitted per second in a unit solid angle one steradian from a uniform source of one candela.
Lux - In photometry lux is defined as the measure of the intensity of light as perceived by the human eye. It is an SI derived unit of luminous emittance and illuminance, which measures luminous flux per unit area. It is equal to one lumen per square metre.
Foot-candle - A foot-candle is a non-SI unit of light intensity or illuminance. This unit is commonly used when designing lighting layouts in parts of the world where SAE units are used. One foot-candle is equivalent to "the illuminance cast on a surface by a non-candela source which is one foot away".
Luminaire - Luminaire is a term used to describe a light fixture, a light fitting or any electrical device which has an electric lamp and provides illumination.
ISOlines - The word ISO originates from Greek which means equal so ISOlines must be a line joining equal parts. In terms of photometry, ISOlines help a lighting designer visualize the lighting levels on a lighting plan. Corresponding to specific foot-candle levels, these lines can be added on a drawing or lighting map to help highlight areas of too much or too less light.

When do you need of a Photometric Analysis or Design

A photometric analysis can be done by using a photometric software and entering the space layout to be designed and adjusted. This gives you an idea of what works, what does not and what can be changed. Allowing the lighting designer as well as the customer to make changes via simulation before the actual construction begins. Here are a few instances when you will need a photometric analysis:

Help Planning Lighting

A photometric analysis is a great way to determine how a lighting solution will work out for a space before you purchase the luminaires. You can simply plan ahead of making any procurements and then implement the best plan.

New Installments

A photometric analysis will be especially helpful when you are about to get new installments for a space and would like to know how the final lighting fixtures will look like. It eliminates the guesswork and an expert can guide you in the right direction.

Visualization of Lights before Installation

With a photometric analysis you can get a visualization of what your space will look like after the lighting fixtures have been installed before they are actually installed. This eliminates the frustration of not getting what you imagined and making changes later as well as avoids incurring extra expenses on making any major changes later.

Meeting Local Codes

Photometric analysis are widely used to make sure that little or no light is trespassing into any neighboring commercial or residential properties and meets the local lighting code. Most local legislations prohibit light trespassing of even one foot-candle. It is smart to get an analysis done before the construction work is carried out.

Photometric Study LED high Bay Light Layout 3D

What are IES Files for lights

All of our light fixtures have what is called an IES file. Think of it as a CAD file for lights. Has the data of what beam angles and intensity the lights come out at. IES stands forThe Illuminating Engineering Society.

We are happy to share IES files, just contact us. (you will need software to open)

Here is the printed version

Several methods to measure light have been around for a couple of centuries. But documenting and standardizing the photometric data has become important only recently, driven largely by computers and the ease. With hundreds of thousands of lights available it became necessary for a standardized format to a. Which is why the IES, Illuminating Engineering Society of America, stepped up which is an organization not only responsible for archiving photometric information but also is dedicated to building photometric maps. They released their IES file format for documenting photometric data in 1986 to the relief of lighting designers and installers.

These IES files consist of two important files, a fixture's luminous intensity and its luminous flux. With these two a lighting designer can determine a fixture's lighting pattern and how it will effect a space. This data used in determining the lighting pattern is generated using a goniophotometer. Imagine a giant globe that is hollow. The light is placed in the center and then closed. Sensors around the inside measure the flux and intensity.

Places Needing a Photometric Study

The photometric technology can be used to effectively analyze light levels and lighting solutions for different indoor and outdoor spaces. Here are a few places that could use photometric studies to determine what the optimal lighting arrangement would be:

Hospitals

Hospital require a photometric study to design a lighting layout that meets the different lighting needs. For example the reception being more lit than the wards etc. Local guidelines need to be kept in mind too for which the photometric analysis is a big help.

Outdoors

Have an outdoor parking lot or sports field that you would want to enjoy at night too? A photometric lighting study will help you plan the best way to illuminate your outdoor spaces and highlight the points of interest. Also you need to be sure of adhering to the local code.

Parking Lots

A photometric analysis is essential for commercial spaces like parking lot lights. The code requires adherence to minimum, maximum and mean light levels. This also addresses security concerns and helps avoid any potential liabilities which arise due to violation of local codes.

Warehouse

You need to maintain a uniform lighting level throughout your warehouse and having a photometric analysis done, especially prior to construction can help you do that. The photometric lighting plan will provide you with the best possible lighting solutions before you buy any LED high bay lights and can make changes as per your needs.

Retail

There must be adequate and uniform lighting in retail outlets like grocery stores so that the produce is well highlighted and customers can easily spot it. For which you must have a photometric analysis done on the retail space. You can also have special lighting arrangement for new product sections by having a different lighting focus on areas you want to be noticed. The best way to get that done is by photometric study.

Stadiums/ Sports Field

Sports facilities and stadium lights are the most common place that require a photometric analysis. The study provides insight on layouts and whether or not the layout will meet the specifications for any given sport or the level of competition. Like a tennis court lights that has multiple courts and requires consistency across them.

What does the result of a Photometric Study look like?

The results of a photometric study consist of 5-20 pages in PDF which contain charts and graphs. See our samples above. The report is prepared adhering to the guidelines provided by the IES and depends on the accuracy of the data provided for the photometric analysis. However, end-user environment and application can cause the actual photometric performance to be different than the result gotten during the photometric analysis.

The following elements are included in a typical photometric study report:

• Graphical Images.

• Charts of lights, locations, angles and foot-candles etc.•

• Lists of foot-candles at various location points on the ground.

• Focus on uniformity as it is crucial for good lighting.

Photometric Study Luminaire Layout

What do you need to get a Photometric Study done?

To get a photometric study done for a space a CAD drawing of the building or location helps or else everything has to be manually entered. The file format is provided by the IES and the data required for it is extracted according to the guidelines laid out.

The lighting specialists then are able to input luminaires, poles, cars, buildings and trees as well as other objects that may impact the illumination of the space that requires the photometric analysis. The photometric software then determines and calculates the light levels based on the data provided.

ISO lines in a Photometric Study

Need a photometric study done? Contact us.

Accepted Answer

dark sky is the idea of keeping light down low and away from higher levels where it can be harmful to birds and astronomy. Often called light pollution, most codes now require at least some consideration to keeping the sky dark or Dark Sky Compliance. These rules help the environment but also save energy as the light goes only where it is used.