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More Money, Less Guesswork: ITE Parking Generation Study and SSc4.4

Parking Generation is a compilation of parking capacity data collected by volunteers through surveys.
Emily Catacchio
June 29, 2010

Pursuing SSc4.4: Alternative Transportation—Parking Capacity in the LEED 2009 NC, CS, and Schools rating systems just got a little more expensive for some projects—$118.75 more to be exact.

The April 2010 LEED Addenda outlines a new “Option 4” for non-residential projects SSc4.4. Now if your project lacks local zoning codes for parking capacity you’ll need to purchase a copy of the 2003 Institute of Transportation Engineers (ITE) Parking Generation study. Rest assured, this book is has plenty of information to back up its price tag. However, the amount you’ll use on just one project is minimal.

Parking Generation is a compilation of parking capacity data collected by volunteers through surveys (samples of which are in Appendix C of the study). While it’s interesting and informative, delving into Parking Generation may seem a bit daunting. Data is organized into approximately 200 charts and graphs; of which only one figure per page is essential for your purposes, the rest, frankly, is just for your information. The study is broken down into 91 Land Use types; such as Manufacturing, Hotel, Marina, Library, Office Building, Apparel Store, and Dry Cleaners. Each Land Use type has at least one report; many have multiple reports organized by hour of day, day of week, month of year, area type, weekday, weekend or peak periods.

Your first task is to figure out which Land Use category your project falls under. These are listed in the Table of Contents organized into larger categories such as 300 Lodging and 800 Retail; making this step much simpler. (You can view the table of contents online at www.ite.org.)

Let’s say your project is an elementary school. You’ll find it under 100 Institutional, and the Land Use code is 520. The corresponding report takes into consideration “…busing policies, the availability of adequate parent pick-up/drop off zones, and lack of adequate parking.” Data to support the recommendations was collected from 7 a.m. to 10 a.m. as well as 2 p.m. to 5 p.m. and it is assumed that the school is centrally located in a residential area. The elementary school report uses “Average Peak Period Parking Demand” versus student numbers on a weekday. 

According to the report, the Average Peak Period is 3–4 p.m.; the Average Peak Period Parking Demand is 0.28 vehicles per student. So to achieve SSc4.4 under this compliance path you need to provide 25% less than 0.28 vehicles per student—that’s 0.21 vehicles per student.

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If your elementary school has 500 students, you would need to have no more than  105 parking spaces to earn this credit.  The simplicity of this calculation and the fact that it spits out an exact number is particularly useful and may save a lot of time.

Parking Generation is not a LEED-specific text, so it has applications outside of LEED, for any project seeking parking capacity guidance.

Purchasing the book (available in softcover, with no PDF version available) will make your first project slightly more expensive, but it could save you time (and therefore money) in the future.


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December 4, 2015 - 4:11 am

We are working on a project that is a warehouse. In the Parking Generation study there are two startegies presented for calculation of average parking demand: one based on the number of employees and the other one based on the squarefootage of the building. Which of these two optons should we choose, should we choose the option that is more strict?

June 13, 2016 - 9:55 pm

I would like to know the answer to this question as well.

February 25, 2015 - 3:16 pm

can any help me find the avg. peak parking demand of an office building? i just can't see myself asking the project to purchase this report just for one simple number!

thanks so much, Courtney

June 18, 2015 - 4:15 pm

Good to hear. We achieved this credit a couple of years back, utilizing scans of the relevant pages, provided by a friendly and helpful traffic engineer.
Good luck!

June 18, 2015 - 4:08 pm

Hi Deborah,

I wasn't able to access it, but i think i just got confused and possibly wasn't looking in the right location. In any case, somehow I was able to find the page i needed doing a google search. Its the same report so assuming I did all my calculations correct, the credit should be achieved. I will be submitting for review in next week or so. First time pursuing the credit using this report.

June 16, 2015 - 7:12 pm

Courtney, I just accessed the information, with my (free) USGBC personal account login. Did you finally manage to access it?
Maria - thanks SO much.

March 2, 2015 - 12:15 pm

so i have a (national) usgbc account, but when i follow the link and click the "guide" tab, the only text written there is about the web based reference guide to "subscribe now." there is nothing else available for me to click "further explanation" or "base ratios."

March 2, 2015 - 2:25 am

All you need is a USGBC account, not the guide. Isn't that free I thought?

February 27, 2015 - 11:29 am

thanks, i don't have a subscription for the web based guide, so i don't think i can access it unfortunately. i really appreciate your help tho.

February 27, 2015 - 2:23 am

No, don’t click resources, the link should send you to the tab called guide (if you have a log in). And under “Guide” you find “Further explanation” with a plus-sign after it in the left column. Under there you have “Base ratios”.

February 26, 2015 - 10:37 am

thanks for quick reply, Maria!

I am having a little trouble following your instructions. When i follow your link, which tab do i then click? If i click on "resources" it brings me to Alternative Transportation Commuting Resource Information website, although the link seems to not be working. Would it be possible for you to provide instructions of where "further explanation" and "base ratios" might be? I imagine its within a report, but i can't seem to access the report.

thanks so much for your help!

February 26, 2015 - 1:59 am

Hi Courtney!
I was just granted two projects to use the table from LEED v4 that can be found at: http://www.usgbc.org/node/2613971?view=guide Look under “Further explanation” and “Base ratios”. You might need a USGBC log-in to get there. And the table is very “fuzzy” (bad copy) and hard to read, but after a while I figured it out by comparing with the formulas in SI-units. There seems to be no official text on this, but it was ok in my case anyways. And remember to be 25 % below these numbers.
Good luck!

February 5, 2014 - 10:54 am

Any update by USGBC on the versioning issues of the ITE Parking Generation Study?

This comment was posted by the USGBC on July 27, 2010 with some comments after it, but none after March 11, 2011. "This is just an FYI - we're aware of this new edition, and are working to insert correct references in our materials."

Have there been any updates as far as if we're able to use the ITE Parking Generation Study, 4th Edition

May 19, 2015 - 3:30 pm

A few months have gone by since this thread was started. Any update by USGBC on the versioning issues of the ITE Parking Generation Study? Can we use the 4th edition?

March 7, 2014 - 11:01 pm

Alfred, I'm not aware that this has been updated. I would recommend contacting GBCI to clarify this point, however. Please post back here if you learn something useful.

July 22, 2013 - 2:42 pm

So do you have to purchase the study in order to do the calculations for LEED? Is there any way to do this without purchasing the document?


January 28, 2015 - 5:01 am

For those of us living in other countries where this study isn't used, do we still have to purchase a copy just to find out the parking number for offices? I wish LEED would just say how many parking spots they want us to provide (or not exceed).

July 29, 2013 - 3:51 pm

Your traffic engineer/consultant should have a copy. Just ask him/her to send you scans of the pages for the relevant building type. Good luck.

March 1, 2012 - 6:56 pm

The ITE Parking Generation Study refferences school population for units in determing # of parking spaces for University/college buildings. For LEED review purposes does ou school population need to be our FTE? We have 10 full time and 19 part time students in our university research facility so could we use 29 for our school population. Any thoughts?

April 5, 2012 - 10:15 am

The ITE Parking Generation Study is only used for SSc4.4, it should not influence your overal FTE. FTE should take into account number of opperation days and influx of transients, etc. Check out the Calculating FTEs forum here.

January 28, 2011 - 3:01 pm

For anyone who is interested, here is a blurb explaining what's new in the 4th edition of the ITE guide:

Parking Generation, 4th Edition: An ITE Informational Report The updated publication represents a substantial change to the third edition, which was published in 2004. The report contains updated introductory material as well as updated land use descriptions, parking generation rates, equations and data plots. The fourth edition also includes a significant amount of new data; updated peak demand rates based on time of day distribution; and quantitative and qualitative information on the influence of numerous factors on parking demand rates. Since the release of the third edition of Parking Generation, information on several land uses has been collected and added to the database. Sixteen new land use classifications and data from more than 450 new study sites are included in the fourth edition, for a total of 106 land uses.

June 4, 2012 - 7:52 pm


I believe you can use the 4th edition.

May 10, 2012 - 9:46 am

It appears the 3rd edition in not for sale on the ITE website. The link takes you to the 4th edition. Can we follow requirements of the 4th edition? Have anybody already tried this credit with the 4th edition? Do you know any CIR about this subjetc (NC 2009)?

July 27, 2010 - 5:56 pm

This is just an FYI - we're aware of this new edition, and are working to insert correct references in our materials.

March 11, 2011 - 12:02 am

Anya, I am not aware of any developments on this from LEED. I'll keep my eyes open, though.

March 7, 2011 - 3:26 pm

I'm wondering if LEED has provided any further guidance on how to interpret the ITE study for schools (esp. regarding parking capacity for multi-purpose functions). It also would be nice to know when they are planning to update the referenced standard to the 4th edition.

March 7, 2011 - 2:42 pm

Do you mean the 3rd vs. the 4th edition of the ITE study? Or the other questions you had earlier?

March 7, 2011 - 2:22 pm

Are there any updates on the ITE interpretation for schools?

July 26, 2010 - 1:43 am

It appears the 3rd edition in not for sale on the website.The link takes you to the 4th editition which according to the ITE website "represents a substantial change to the third edition". Is it necessary to find a copy of the 3rd edition, or will using the 4th edition suffice for LEED purposes?

May 20, 2014 - 11:50 pm

Our project is located outside of the US, and none of our engineers have ITE parking generation study. We have just purchased 2010 edition, because former editions are not available anymore. LEED refers to 2003 ediion, so probably required parking space ratio is less than the current version. Is it acceptable to use parking space ratio indicated in the current version instead of 2003 edition? Any comments are appreciated. Thank you.

Noriko Yasuhara

October 14, 2011 - 1:17 pm

Unfortunately, no, we won't have an opportunity to test this method out. We determined that the approach described above still did not cover the parking required by our client. We are attempting to use the client parking requirement (since it came from a gov't agency that oversees this specific region) as local code. Sorry, our approach won't help shed light on the ambiguous issue of how to apply the ITE Parking Study for schools. I hope someone else can help clarify this for future projects.

October 14, 2011 - 5:55 am

Hi Anya,

Do you have any feedback yet on how this approach was received? How did it work out?

February 18, 2011 - 11:53 pm

Thanks Larry, this sounds like a fair approach. Perhaps we could use the ITE factor for staff parking only, and propose a reasonable methodology for the multi-purpose space parking needs (to cover sports and cultural events and parent-teacher conferences). We could then subtract 25% of that total parking capacity to meet the LEED intent. Has anyone else tried this? We'll go ahead and submit this credit and share what we learn in the review process.

February 16, 2011 - 1:35 pm

NCv2.2 referenced Oregon State code but no longer in 2009. I looked at the OR code and it listed 1-1.5 parking spaces per classroom. I was going to suggest using this as an alternative but it might equate to even less than what you have now (not knowing how many classrooms you have). If your site is to have special events, my suggestion would be to conduct a fair estimate and assume single drivers to an event - perhaps 1 per student - thinking of parent/teacher nights. Then take 25% of that number with the hopes that parking stall numbers will be more reasonable. Since your school is remote, it seems fair assuming there is no major public transportation available to students, staff or visitors. I don't think this would become an alternate compliance path since you would be following the ITE guide for the most part. I hope this was somewhat helpful.

February 2, 2011 - 1:28 pm

That is unclear... I did notice a clause in the ITE study that says, "For all school uses, it is important to collect data on the size of the building and total number of students, faculty and employees in order to accurately measure parking demand for the site."

The ITE study goes on to say "Additional parking demand observations should include evening hours and when special events occur at the site (for example, special programs or sports field usage). If available, the type of the event or number of sports fields in use should be documented."

Sufficiently vague? They mention the importance of adressing school specific parking issues, but offer no guidelines for how to calculate parking to serve those uses over and above the recommended average parking per student.

I double checked the LEED form and all it asks for is "Number of parking spaces suggested by ITE "Parking Generation" study:"

It then requires you to "Provide documentation showing the project team's assumptions used to determine the total vehicle parking capacity relative to the applicable standard listed in the 2003 Institute of Transportation Engineers (ITE) "Parking Generation" study. Include the relevant sections of the referenced standard."

Any help interpreting all this would be greatly appreciated :)

February 1, 2011 - 9:32 pm

Sorry if this is obvious, but are you reading the ITE study right? Could it mean 0.17 vehicles per student on top of staff parking?

February 1, 2011 - 8:51 pm

We noticed the ITE 4th edition shows 0.17 vehicles per student (average peak parking demand) for elementary schools. 25% less would mean 0.1275 vehicles per student. This seems much too low. For our school with 86 students, that means only 11 or 12 parking spaces, depending if you round up or down. However, we have 15 staff and 10 volunteers at peak periods. Even using the above reference of 0.21 parking spaces per student, we barely get 20 parking spaces! We are scrambling to find an alternate parking standard to reference, but this school is very remote, with no city or county zoning. Any suggestions?

Another issue we have is parking to accommodate events in the gym/multi-purpose room. Has anyone determined how to address parking for these spaces? Advice is much appreciated!