Table of Contents
Introduction
Overview of how the SEAD Street Lighting Tool can help save energy and
improve light quality in street lighting
SEAD Street Lighting Tool Features
Highlights of the SEAD Street Lighting Tool’s analysis process, road configuration
options, fixture choices and calculations, and basic financial analysis
Page 1
Page 1
Applications of the SEAD Street Lighting Tool for Specific User
Profiles
How the SEAD Street Lighting Tool could benefit a variety of users, including
small municipalities, first-time users, experienced lighting designers and
manufacturers
Page 3
Proposed Fixture Specification Process Using the SEAD Street
Lighting Tool
An efficient analysis process for designers that involves collecting IES files for
potential fixtures, analyzing fixtures using the SEAD Street Lighting Tool and
soliciting bids to select products
Page 4
Conclusion
How the SEAD Street Lighting Tool maximizes energy performance, light quality
and total cost of ownership
Page 5
Getting Started
How to download the SEAD Street
Lighting Tool
Page 6
Doing an Analysis
Appendix A: Using the SEAD
Street Lighting Tool
Using road geometry, light levels,
fixture selection, IES files and cost
information
Page 6
Analyzing Results
Results available for single fixture and
multiple fixture analyses
Page 9
Saving Energy and Improving Light Quality in Street Lighting
Applications of the SEAD Street Lighting Tool
The SEAD Street Lighting Tool is designed to make it easy to find the best fixture for your roadway in order to
improve light quality and achieve energy savings in municipal street lighting upgrades. With the emergence of
new lighting technologies, conventional performance benchmarks like wattage and light distribution type are
not sufficient to know how a fixture will perform. Further, with so many fixture choices available, it can be
difficult to find the ones most appropriate for a given road layout.
This SEAD Street Lighting Tool provides a streamlined method for analyzing the energy use, light quality, and lifecycle cost1 of the most common road configurations. The street lighting tool offers the following benefits:

By combining basic photometric analysis with life cycle cost and energy analysis, the tool provides a
streamlined evaluation of fixture performance and a better understanding of tradeoffs.

The simple step-by-step approach makes it quick and easy to create preliminary street lighting designs
of the most common road layouts, even for novice users.

The ability to analyze a large number of fixtures simultaneously allows beginner and advanced
designers alike to identify the fixtures most likely to meet desired targets.
This white paper outlines the functionality of the SEAD Street Lighting Tool, discusses some potential audience
types and applications, and provides a step-by-step guide to conducting an analysis using the SEAD Street
Lighting Tool.
SEAD Street Lighting Tool Features
The SEAD Street Lighting Tool can be used any time a lighting designer is considering installing new fixtures,
whether it is for new construction, fixture upgrades or a redesign of an existing road. Photometric analysis is the
process of estimating the lighting levels across the road surface, using the characteristics of the light fixtures
used, road geometry and road surface. It is used to predict the brightness and light quality of street lighting, and
is critical to selecting appropriate fixtures. The SEAD Street Lighting Tool integrates photometric analysis with
energy consumption and life cycle cost analyses. The user can input site-specific variables that represent the
most common road layouts, providing faster and easier screening of fixtures to identify the candidates that are
best suited for a more in-depth analysis. A primary feature of the SEAD Street Lighting Tool is its ability to
perform photometric analysis for many fixture choices at once, making it particularly useful for comparing
fixture choices for lighting upgrades where the fixture layout will stay the same.
1
Life-cycle cost refers to energy cost over the lifetime of the product, not embedded cradle-to-grave costs.
Street Lighting Tool | 1
Analysis Process




Quick comparison of a single upgraded fixture to the existing baseline.
Batch method allows users to simulate dozens or hundreds of fixtures at once for a given road layout,
making the street lighting tool particularly suited for lighting upgrades where only fixtures are replaced.
Analyses can be saved to allow for comparisons between changing road and pole layout scenarios,
useful for new roads or upgrades to existing roads that may involve road layout changes.
Three example analyses included in the SEAD Street Lighting Tool can help users quickly assess tool
functionality.
Road Configuration Options


Lane options available include two, four and six lane roads.
Pole configurations available are single-side, staggered and median-mounted pole layouts.

Spacing and sizes can be altered, including site-specific lane width, pole height, pole spacing and arm
length.
Fixture Choices



37 generic fixtures can be used for testing and comparison purposes (including High Pressure Sodium,
Metal Halide and Light Emitting Diode).
Add your own fixtures by uploading the IESNA data2 or other compatible data to the SEAD Street
Lighting Tool.
Both LED and conventional fixtures can be analyzed.
Fixture Calculations



Luminance and illuminance calculations can be made using the IES method3.
Light level and uniformity targets can be met by the quick identification of fixtures that meet your
desired goals.
Annual energy use is reported per fixture and as kWh/kilometer/year.
Basic Financial Analysis



Projects-level inputs for fixture installation labor, pole installation and bulb replacement cost.
Fixture-specific inputs for fixture costs and expected life.
Life cycle cost analysis.
2
The Illumination Engineering Society of North America (IESNA) provides a standardized format for manufacturers to report
photometric data electronically. The filename extension for these files is .ies.
3
IESNA also stipulates how photometric calculations should be performed in their standard IESNA RP-8 American National
Standard Practice for Roadway Lighting.
Street Lighting Tool | 2
Applications of the SEAD Street Lighting Tool
for Specific User Profiles
This section outlines sample user profiles and how they might benefit from the SEAD Street Lighting Tool.
1. Small Municipality or First-Time User
User Profile and Common Situation:
For small municipalities, the addition of new roads or the renovation of existing roads may occur too
infrequently to justify a dedicated staff member for lighting design, and may not have in-house experience in
photometric analysis.
Application of the SEAD Street Lighting Tool:
The SEAD Street Lighting Tool’s design allows for simple, straightforward evaluation of lighting fixture options in
a step-by-step process. The street lighting tool intentionally simplifies the photometric analysis to enable firsttime users to perform a first-level assessment of lighting options using common road configurations. While
advanced lighting design software should be used to verify final design, the SEAD Street Lighting Tool could be
used by beginners to:



Verify manufacturer claims of lighting performance when supplied with bid requests.
Conduct early scoping studies on the feasibility of lighting retrofit. This analysis could be used to justify
the hiring of a consultant to provide professional design help.
Provide basic photometric analysis for purchasers who are not currently using photometric analysis
when selecting fixtures.
2. Experienced Lighting Designer
User Profile and Common Situation:
Experienced lighting designers typically have a good sense for which fixtures will likely be best for a particular
road. However, with today’s latest technology, wattage is a less reliable indicator of total light output from a
luminaire, and light distribution can also vary widely within a particular distribution type (IES Type II, III, etc.).
Photometric analysis is necessary to accurately account for costs in light of changing technology and the
emergence of new fixture choices. For lighting retrofits, pole spacing and height are typically fixed, and fixture
selection is critical to maximizing energy savings.
Application of the SEAD Street Lighting Tool:
When analyzing fixture choices individually, lighting designers are limited in the number of fixtures they can
analyze. The SEAD Street Lighting Tool is designed to make pre-screening of fixture choices faster and easier;
tens or hundreds of fixture choices can be analyzed in a single batch for a particular road and pole configuration.
An experienced designer might use the SEAD Street Lighting Tool to:


Pre-screen fixture options to find the top performers that meet light quality targets. For a more
complete description of this application, see the next section, Proposed Fixture Specification Process
Using the SEAD Street Lighting Tool.
Conduct early stage analysis quickly and easily.
Street Lighting Tool | 3

Integrate life cycle cost analysis into their fixture specification process.
3. Manufacturer
Application of the SEAD Street Lighting Tool:
Manufacturers often receive requests to recommend the best fixture of those they sell for a particular road
configuration. The SEAD Street Lighting Tool can optimize this selection process and provide consistent
recommendations across an organization. A manufacturer might use the SEAD Street Lighting Tool to:



Create a library of its fixtures with price and photometric data.
Identify the best candidate fixtures for a client’s specific road layout in a consistent manner, by
analyzing all their company’s fixture choices in a single batch.
Highlight alternatives, where a small increase in price or energy might yield significantly better
uniformity and/or light levels, by integrating life cycle cost analysis with their photometric analysis and
more easily comparing photometric performance across fixtures.
Proposed Fixture Specification Process Using the SEAD Street Lighting Tool
Many lighting designers rely on recommendations from manufacturers in deciding which fixtures to analyze for
their roadway, particularly when trying to identify appropriate LED fixtures. Due to the significant difference in
conventional and LED lighting technologies, it is difficult to provide one-to-one replacement suggestions easily.
Many designers will ask a manufacturer to specify the street light model that is equivalent to a particular
conventional street light or that meets certain lighting level targets, and only evaluate the recommended
fixtures.
While this approach can often yield reasonable results, some problems were highlighted in a National Lighting
Product Information Program (NLPIP) report published in 20104. The authors asked manufacturers to identify
street light models that were equivalent to a specific conventional fixture. The resulting LED streetlights
evaluated in the report were significantly underpowered – a problem that the authors ascribed to manufacturer
sales representatives’ recommendations for under-powered fixtures. This problem is likely reflected in real
product purchasing.
Additionally, there are limitations to the number of fixtures that a designer can assess. Conventional lighting
software applications have features for pole spacing optimization, but not for fixture optimization. Designers
must analyze fixture options one-by-one, and assemble these into their own comparison report.
The SEAD Street Lighting Tool may be integrated into a typical selection process to pre-screen many fixtures for
their light and energy performance before all design criteria for that fixture are verified. Designers can analyze
the light quality and energy performance characteristics of many more fixtures – and save the tedious manual
process of verifying detailed performance criteria for those fixtures that have the best performance. The
proposed approach, detailed below, provides a more efficient analysis process for designers.
4
NLPIP 2010, “Specifier Reports: Streetlights for Collector Roads.”
http://www.lrc.rpi.edu/nlpip/publicationDetails.asp?id=927&type=1
Street Lighting Tool | 4
Proposed approach:
1. Contact manufacturers or visit their websites to collect IES files for potential fixtures.
Selection criteria can be much broader than the typical bid request; for instance, a designer might
include many fixtures that appear over- or under-powered for their application, rather than asking the
manufacturer to identify its best fixture for a specific road configuration.
 The designer should verify actual wattage and any easily verifiable, mandatory requirements –
but by doing most of the verification after pre-screening, designers can evaluate more fixture
options with less effort.
 While specific costs may be used, cost estimates can be sufficient for pre-screening.
 Building a library of verified pre-screened fixtures can make for faster evaluation of new road
configurations. By including all fixtures, designers may select a fixture they otherwise would not
have considered.
2. Perform an analysis for all fixtures using the SEAD Street Lighting Tool
 Identify the top energy and cost performers that meet or exceed light level targets.
3. Work with manufacturers to solicit formal bids of top performers
 By first screening many fixtures for their energy, light, and life cycle cost performance, verify
performance parameters for the top-performing fixtures for the particular road.
 If the products being considered include LED fixtures, the Municipal Solid State Lighting
Consortium provides a model specification5 that includes many important LED-specific criteria.
4. Finalize product selection
 Verify light performance using professional lighting design software6, including any site-specific
details not represented in the SEAD Street Lighting Tool. Life cycle cost estimates can be verified
through a detailed cost analysis.
 For financial analysis, the MSSLC has a financial analysis tool7 available that allows users to
evaluate the many financial variables specific to street lighting.
Conclusion
Street lighting design is a complicated process. However, the SEAD Street Lighting Tool can help ensure the
appropriate street lights are selected to maximize energy performance, light quality, and total cost of
ownership. To download the most recent copy of the SEAD Street Lighting Tool, visit www.superefficient.org.
For any questions or feedback, please send an email to sltoolkit@superefficient.org.
5
The model specification is available for download: http://www1.eere.energy.gov/buildings/ssl/specification.html
Such as AGi32, Dialux, Lighting Reality, or Visual, which can be used for more detailed light quality analysis.
7
Financial analysis tool: http://www1.eere.energy.gov/buildings/ssl/financial-tool.html
6
Street Lighting Tool | 5
Appendix A: Using the SEAD Street Lighting Tool
Getting Started
The SEAD Street Lighting Tool is a Microsoft Excel-based tool for calculating average luminance and illuminance,
uniformity, energy use, and life cycle cost. The SEAD Street Lighting Tool is available for download from the
SEAD website, www.superefficient.org. The SEAD Street Lighting Tool is free to download and distribute.




The first step to using the SEAD Street Lighting Tool is to enable macros for Excel; instructions for how to
do this for your version of Excel should be readily available through an internet search.
The tool is compatible with Excel 2003, 2007 and 2010.
The tool is laid out in a series of worksheets that generally flow from left to right, denoted by a series of
tabs along the bottom of the screen. Hyperlinks in the form of gray arrows allow users to move between
worksheets.
The SEAD Street Lighting Tool is currently available in English, with translation to French, Spanish and
other languages underway. If you would like to add another language, please contact the development
team at sltoolkit@superefficient.org.
Upon initial download, the input fields will have no entries or results saved. For users wishing to explore the
SEAD Street Lighting Tool’s functionality, analysis examples can be launched via the drop-down menu on the
Examples worksheet.
Doing an analysis
All steps of the analysis revolve around the Inputs worksheet. As noted on
the right, color coding indicates different types of cells on the worksheet.
Step 1: Road Geometry
The road geometry section on the Inputs worksheet provides a quick
summary of the values entered on the Road Geometry worksheet. To
input the road geometry, click on the arrow to go to the other worksheet.




x
x
x
Required inputs are yellow
Values from other tabs are
blue - follow the yellow
arrows to change
Navigation buttons are gray
Separate columns are provided for the “baseline” and “upgrade” scenarios. If the same road and pole
spacing are being compared, the values in both columns will be identical.
When a cell is selected, a pop-up box will show you the definition of that term.
One input to pay attention to is “Number of Points in Grid.” The SEAD Street Lighting Tool uses the IES
methodology, which specifies the number of points that must be used to calculate light levels. Rather
than calculating this automatically, the tool allows the user to specify their own number of
measurement points. To be compliant with the IES calculation methodology, the “Number of Points In
Grid” should be at least 10; furthermore, the spacing of the grid must not be greater than 5 meters. If
row 23 shows a higher value, you should increase the number of points (up to 20) to get the spacing to
match 5 meters.
The two graphs on the right side of the worksheet provide a quick visual representation of the road
layout. The red dots indicate the measurement grid, while the orange and purple markers indicate the
Street Lighting Tool | 6
locations of fixtures. Be sure to note that the fixture location is where the actual light fixture is located,
rather than the pole base.
This is an example of the graph demonstrating the layout of the road geometry and measurement grid.
Yellow and white lines indicate lane markings, the red dots indicate the location of the measurement
grid, and the orange and purple markers indicate fixture locations.
Step 2: Light Levels
The street lighting tool allows you to enter the light level targets you would like the fixtures to meet. These
targets only determine reference lines in the light level graphs – they do not affect the light level calculations on
the road itself. They also affect the color coding in the results graphs that help indicate which fixtures do and do
not meet your light level targets.



Inputs for both the illuminance and luminance methods are included. Both calculations are performed,
but you can compare using just one method of calculation if you prefer.
Targets specified by the IESNA RP-8 and CIE 115 standards are included for reference. To view the
written summary for a particular standard, simply select it from the drop-down menu.
If you would like to add written documentation about another lighting standard, you can do so by
clicking “Add Standard” from the drop-down menu. This will provide you with space to add any
descriptive information you would like. Once the description has been entered, click “Save Standard.”
Adding a standard does not affect the calculations.
Please note that some important light quality variables are not included, such as glare calculations. Additionally,
while the CIE recommended values are included for reference, calculations are done using the IES methodology,
which differs in some calculation assumptions. Final design should be verified using professional lighting design
software.
Step 3: Select Fixtures
There are two methods for selecting which fixtures to calculate:


To compare results of a single fixture choice to your existing (baseline) choice, you can select the fixtures
directly from the two drop-down menus.
To perform an analysis on many fixtures simultaneously, use the “Select Multiple Fixtures” option. For
comparison, you should still select the baseline fixture in the menu.
Street Lighting Tool | 7
o

Select which fixtures to calculate on the Fixtures worksheet. Most assumptions about the
fixtures are stored here. Specific photometric data are stored on the gray Fixture Data
worksheet.
o To include a fixture in a batch analysis, place an “x” in the yellow column B – the row should be
highlighted in blue if it is selected.
On the Fixtures worksheet, you can modify some of the fixture assumptions. The yellow cells on the
right can be edited directly to change these assumptions. Wattage may also be edited, but care should
be taken to ensure that the value is actual wattage rather than nominal wattage.
Adding IES files
Photometric data for specific fixtures can be added by using the “Add IES file” button on the Inputs worksheet.





After selecting the file, enter a descriptive name.
The entry for fixture type (HPS for High Pressure Sodium, MH for Metal Halide, or LED for Light Emitting
Diode) is used only to automatically populate the default assumptions of fixture cost, lumen
depreciation, etc. After the file is uploaded, you may change these assumptions on the Fixtures
worksheet.
You can also add many IES files at once. On the Add IES Files worksheet, enter the list of all the IES files,
including full file path (e.g. Filename.IES), the reference name, and fixture type. Click “Begin upload…” to
load all files at once. You will be notified of any errors as files are added.
If you would like to remove a previously added fixture, use the “Delete Fixture Data” button. Simply
select the fixture from the drop-down menu and it will be deleted from both the Fixtures worksheet and
the FixtureData worksheet. Note that this cannot be undone.
Due to the number of available columns in Excel, IES files that specify the light output at increments
small enough to have more than 256 vertical angles cannot be added and saved to the SEAD Street
Lighting Tool.
Occasionally, IES files are not formatted appropriately and the upload does not work. If you encounter this
problem, please send the problematic IES file to sltoolkit@superefficient.org. We will debug the upload process
for future versions.
Step 4: Cost Information
Some costs are included on the Inputs worksheet, while fixture-specific costs are included on the Fixtures
worksheet.


In a retrofit scenario where poles will not be moved, enter “zero” for pole installation costs.
The discount rate is used for performing the net present value calculations. The discount rate should be
reduced to account for inflation. This methodology implicitly assumes that material costs, labor costs,
and energy costs will all have the same rate of inflation.
Street Lighting Tool | 8
Step 5: Run Analysis
There are separate buttons for single-fixture or multiple-fixture analyses. For a single-fixture analysis, click the
“single-fixture” button on the Inputs worksheet or navigate to the SReport worksheet. For multi-fixture analyses,
click the “Calculate Multiple Fixtures” button on the Inputs worksheet to run the macro that calculates batch
fixtures.
Analyzing Results
Results are provided separately for single-fixture and multiple-fixture analyses:


The single fixture results are on the SReport worksheet, with detailed luminance and illuminance values
for the measurement grid provided on the SReportGrid worksheet.
The multi-fixture results are shown on the MGraphs worksheet, while the tabular results are stored on
the MResults worksheet.
Sample SEAD Street Lighting Tool Outputs


Energy is shown on the left axis,
illuminance on the right.
Red dotted lines show the minimum and
average illuminance targets.
The labels on the bottom of the graph
correspond to the scenario name that was
entered before the results were
calculated.
70,000
kWh/kilometer/year

60,000
50,000
40,000
30,000
20,000
10,000
0
Annual Energy and Illuminance
40.0
35.0
30.0
25.0
20.0
15.0
10.0
5.0
0.0
Illuminance (Lux)
kWh/kilometer/year
Annual energy use of all modeled fixtures; by
Annual Energy Use - All Fixtures (Illuminance Filtered)
default, results are sorted from lowest to highest
70,000
energy use.
60,000
 Results that fail the light quality criteria are
50,000
shown in gray, allowing you to focus on
40,000
fixtures that meet your targets.
30,000
 Two similar graphs are provided, one using the
20,000
10,000
illuminance targets and one using the
0
luminance targets, as provided on the
“Lighting Standards” tab. These will often be
Baseline Energy
Meets Illuminance Criteria
Fails Illuminance Criteria
different for the fixtures that just meet the
criteria. A sample graph is shown to the right.
 Hovering over a fixture bar will show you the
fixture name and energy use, which can be
explored in depth in the graphs below
The remaining graphs in the tool only show 10 results at a time – use the scroll bar show different results. The
scenario definition is shown in the table above the graphs.
Annual energy use plus illuminance values
Street Lighting Tool | 9
Illuminance - Min, Avg and Max
40
Illuminance (Lux)
Range of illuminance and luminance for each
fixture, as compared to the targets. These graphs
can be used to see why a particular fixture passes
or fails the selection criteria, and by how much.
Max
30
20
Avg
10
Min
0
Net Present Value - Lifetime Cost
Lifecycle cost
The net present value graph shows the
contribution of energy cost, installation cost, and
maintenance costs for each fixture. These are
calculated using the user-specified discount rate
and energy rates.
$175,000
$150,000
$125,000
$100,000
$75,000
$50,000
$25,000
$0
By default all results are sorted based on energy consumption. You can also sort by energy, net present value
(NPV), average illuminance, or average luminance by selecting one of the buttons to the right of the results
table.
MResults
Rows one through three on the MResults worksheet cannot be changed. However, the rest of the rows may be
rearranged or deleted as you see fit. To clear all results on the MResults worksheet, simply delete all data in
rows 4 and below, or use the ‘Delete Results’ button on the Inputs worksheet.
Street Lighting Tool | 10