Daylighting Simulation in LEED 2009: 2 Models = Unanswered Questions

Despite the fact that I almost live on the interwebs and have a penchant for butchering images in photoshop, I'm not the most technologically advanced person when it comes to Revit and the bevy of associated environmental modeling programs available. I got an email from one of my colleagues asking how to interpret the following requirement for compliance with EQc8.1, Daylight and Views, Daylight credit using Option 1, Simulation, and I'd like your help in determining an appropriate response:

"Demonstrate through computer simulations that 75% or more of all regularly occupied spaces areas achieve daylight illuminance levels of a minimum of 25 footcandles (fc) and a maximum of 500 fc in a clear sky condition on September 21 at 9 a.m. and 3 p.m...”

The issue here is that they ask you to generate two models (one at 9am and the other at 3pm), but no guidance is provided about how to combine these models to show that 75% of the space meets the footcandle requirements...

What the hell does this image have to do with a post about daylighting compliance?*

Previous editions of LEED forced you to simulate the daylighting levels at noon, and I suspect that by using solar positions that are 'lower' in the sky more projects should be able to claim credit since daylight should penetrate more deeply into the building. The reference guide goes on to discuss other issues surrounding the simulation, but none resolve the problem brought to my attention earlier today. My reading of this leads me to two possible interpretations:

'Subtractive' Compliance

In the 'subtractive' compliance scenario, you would take the two floor plans and run the daylight intensity model for both and mark the compliant square footage on each. You would then combine the two models, and only include the spaces that are compliant on BOTH models in your calculations to determine if 75% of the overall regularly occupied space and mark your compliant square footage. The result is a combined space that is smaller than either model individually.

'Additive' Compliance

This interpretation would require you to generate the two models, but instead of cutting out the spaces that are not compliant at both times, you combine the two for a larger footprint than was created by either model.

The final word?

After I wrote 95% of this post, it occurred to me I should scan the forums for an answer, and I found a reasonably definitive answer on the LEEDuser forums**, courtesy of Jill Dalglish at Dalglish Daylighting:

"I received this statement in a response from USGBC Technical Customer Service: 'The simulation needs to document compliance at both 9:00 a.m. and 3:00 p.m.. Only areas that meet the requirements at both of these times are considered complaint.' To me, this means that you cannot take an average and you cannot evaluate the two times separately, ie. you cannot include the space in the compliant area if 75% of it meets the footcandle requirement at 9am and then also meets it at 75% at 3pm (unless that 75% overlaps.)"

This clearly supports the 'subtractive' method of compliance, but I'd love to hear from someone who has performed and submitted and had this strategy approved in a LEED review. Please share your experience by leaving a comment!

Forgive my Rant

Another sidenote to anyone at the USGBC responsible for developing the reference manuals: This is ridiculous! It's one thing that this slipped through the cracks in the first edition of the reference guide, but to also miss it in the addenda makes me want to scream... It would be one thing if it was a minor issue, but people cannot complete their documentation without this critical piece of knowledge! How is this overlooked (at least) twice?

* Free kudos and (if desired) a link to the site of your choice to the first commenter who points out what, if anything, this picture has to do with this post... Liz, you can't enter!

** FULL DISCLOSURE: LEEDuser is a sponsor of this site... I know there's been a bunch of of 'full disclosure' posts lately, and I can only offer my word that it's not by design! I really do use my sponsor's sites on a regular basis.

The Cost of LEED Review: Relatively Great, Specifically Problematic

A few weeks ago I was provided with a copy of The Cost of LEED whitepaper ($49 + shipping) from BuildingGreen*, and I must say I'm impressed. The report is by no means flawless, but it's the first one I've seen that provides designers with a credit-by-credit 'back of napkin' figures to use to calculate cost premiums for various design strategies.

To my knowledge the only thing that even comes close is a useful but (in some ways) less detailed study from the GSA in 2004. It's worth noting that the GSA study is free, but is limited to GSA office and courthouses for its scope and does not list specific construction cost premiums for each credit. Let's take a look at a sample page from the BuildingGreen report to get a feel for the document and then I'll offer up some pros and cons: Example Credit Report - WEc3

Sample Credit Report for WEc3 - Click to view Full Size - Reprinted With Permission

This profile of credit WEc3, Water Use Reduction is fairly typical... setting 'conventional' systems as the cost baseline and indicating specific premiums for various upgrades that may be used when pursuing the LEED points. It's important to point out that this is probably one of the longest credit reports in the whitepaper, as more than a few strategies (e.g. SSc1, Site Selection or SSc4.1) are so dependent on local site factors as to be unquantifiable in any realistic sense. Assumptions are pointed out when appropriate and in general I feel like you're provided with enough information to make adjustments on the fly if you have strange circumstances. The report only covers the LEED-NC v3 rating system, so if you're pursuing anything other than LEED-NC or LEED-CS this report will be of limited value.


I see two major problems with this whitepaper. The first and most significant is that soft costs of LEED (energy modeling, documentation fees and the like) are not provided. I think the soft costs component of LEED premiums have not been discussed sufficiently as an industry, and from my limited experience I've found fees still vary significantly from consultant to consultant. I would have greatly appreciated a section that attempted to provide some ground rules for costs from civil engineers, MEP engineers, architects, contractors, specialty LEED consultants, etc. It's worth noting that commissioning costs are the exception to this rule and are included in the report. It's also worth noting that the GSA study takes a stab at soft costs (see page 6), though it lumps all parties into a single figure that isn't terribly useful.

The second lies in the accuracy of the specific costs listed for each specific measure, and I could be off base about this. Not being a cost estimator myself, I've taken informal polls from a few people in design and engineering fields locally, and the consistent response is that the costs 'seem high'. I think this is likely due to the fact that "cost data is based on northeastern US construction costs from 2008." I'm in South Carolina, and it only stands to reason that everything would be cheaper here, but that doesn't change the fact that those costs would likely need to be adjusted across regions and time. In their defense, these issues are presented right up-front in the Assumptions and Qualifications section.


Ultimately the strength of this report lies in the "Construction Cost - Relative Percentage" tabs for every credit. The simple multipliers allow you to consider the impact of adding credits early in the design phase, and the Cost Synergies section helps ensure you're not making those decisions in such isolation as to not understand the impact on other points you may be considering. It allows you to have an answer, however rough, when a client asks you a question like, "How much would it cost if we decided to switch from our dark roof to a light TPO membrane?" The use of concise charts allow you to do this in a report that is only 47 pages, yet at the same time it includes at least one strategy I haven't even heard of (e.g. aircuity systems).

*FULL DISCLOSURE: BuildingGreen operates, a sponsor of this site. The copy of the Cost of LEED report was provided free of charge for review purposes. That said, I stand by the review I've posted as an accurate and un-biased portrayal of the report's value, and I would make the same report even if LEEDuser were not a sponsor of this site. If you feel I've overlooked or omitted anything important please speak up by leaving a comment!

5 Ways Your LEED Project Can Be Challenged, Cancelled, or *GASP* Revoked!

Though it hasn't received a tremendous amount of attention*, part of the LEED v3 updates included various paths by which LEED project registrations can be cancelled and people can challenge existing LEED certifications and possibly have those projects' LEED status revoked!

If you haven't browsed it yet, I would highly recommend flipping through the GBCI LEED Policy Manual, which lays out the basic regulations surrounding these and other issues that you should know about before starting a LEED project. The following headings are largely copies of the chapters in the policy manual (pgs 12-17), but I've shortened the text to show only the critical requirements in each category

1. Your Project Wasn't Submitted Before the Rating System Sunset Date

With the start of LEED v3 the GBCI instituted a 'registration cancellation policy' that sets a few deadlines that you have to meet or else the GBCI is authorized to void your registration. The "'Sunset Date' refers to the date occurring six (6) years after the close of registration for a rating system version." e.g. Registration for LEED-NC v2.2 closed on June 26, 2009**, meaning that at least a design certification review for a LEED-NC v2.2 project must be submitted by June 26, 2015 or the GBCI can decline to review the project. If you submit a design review before the sunset date you have up to 1 additional year from the date of the design submission to submit the construction review.

I don't really have a problem with this requirement, as the GBCI can't be expected to staff reviewers with knowledge in every version of the rating system since the beginning of the LEED over 10 years ago. 6 years should be ample time even for the longest project schedules (though possibly not LEED for Neighborhood Development). It also appears as though this requirement applies retroactively, as the USGBC closed reviews of LEED-NC v2.0 projects on December 31, 2009. To date, the USGBC has offered free 'upgrades' to new systems as their launched, though there's no guarantee this will happen in the future.

Simply Terrible...

Let's a take a moment to admit that some cancellations are for the best

2. Your Project Has Been Inactive on LEED Online for Too Long

"GBCI reserves the right to cancel any project that, as determined solely by GBCI, remains inactive for a period of four (4) years or more." The note goes on to say no refunds will be provided. I'm not wild about this requirement, as I can't figure the purpose. I suppose it's to prevent crafty LEED administrators from purchasing a bunch of registrations well in advance of actually starting projects so that they may lock in the typically less restrictive requirements of earlier systems. Just because the GBCI can revoke a registration in this manner doesn't mean they will, and I would assume some sort of warning would be announced to the project administrator prior to shutting it down. I still don't like it though, because it seems necessary given the sunset date requirements.

3. You Waited Too Long to Submit After Project Completion

The new rules also state that an NC, CS, or CI project has no more than two years after the "Project Completion Date" to submit for review. I'm also a little unclear about the purpose of this requirement. In every project I've worked on the owner provides plenty of incentive to get the certification finished, and I don't know why the GBCI cares either way how timely the submittal is tied to the completion date. Again it seems like the sunset dates should be the only really necessary restriction.

4. Someone Challenged Your Certification Rating (and They Were Right)

While the registration cancellation policies discussed above are pretty straightforward, the Certification Challenge Policy is an interesting can of worms in that anyone can initiate regardless of their involvement in the project. These challenges occur after a project has completed the certification, and can result in anything from a loss of one or more points to a complete revocation of the certification altogether. It's not just credits that are potentially considered, but also compliance with the Minimum Program Requirements.

A formal investigation can be launched by the GBCI itself without third party complaints or by anyone in the general public, though they cannot do so anonymously... From the policy manual:

Persons desiring to make a complaint may submit a written statement identifying the persons alleged to be involved and the facts concerning the alleged conduct in detail, and, to the extent available, the statement shall be accompanied by any available documentation. The statement shall identify others who may have knowledge of the facts and circumstances concerning the allegation. The person making the complaint shall identify him/herself by name, address, and telephone number.

Once a complaint has been filed, no one less than the GBCI President him/herself reviews the complaint (with the help of their legal counsel, of course), and can either dismiss the complaint immediately if deemed frivolous or initiate an investigation that can potentially include further documentation from the project manager or owner or even include site visits. Should the GBCI determine there was indeed some form of false representation or inaccuracy in the original submittal, there's a whole load of notifications, appeals and such that I'm not going to cover here. I'll assume that should this ever happen to you you're likely to take the time to read the policy manual yourself!

To my knowledge there has been only one certification challenge to date. It was against the LEED Gold certified Northland Pines High School in Wisconsin... The GBCI has at this point denied the challenge and elected to maintain the certification, but a new post today from the Green Building Law Update shows that the five challengers haven't given up... Interestingly, all of those involved in the challenge (an architect, a developer, a contractor, a chiropractor, and a 'local businessman and community leader) served on the building committee for the project. They recently released all of their challenge documentation and a statement about their dissatisfaction with the denial of the challenge. I'm not going into it here, but it gets pretty interesting when you consider their claim that "[The GBCI] based [the denial of the challenge] on reports from two more consulting engineers who said that the building did not meet the prerequisites but concluded that “pretty close” is close enough." I expect that we'll hear far more on this in the near future.

5. You Forgot To Recertify Your LEED-EB Project

LEED for Existing Buildings projects must recertify the project every five years to maintain their certification. It is the only rating system that requires re-certification at this time and this is nothing new... it's always been this way.

*It hasn't been discussed much except by Chris Cheatham, founder of Green Building Law Update, who can't seem to shut up about it lately... Seriously though his coverage of the LEED Certification Challenge policy is a highly recommended read, especially as the ongoing drama surrounding the Northland Pines project develops. The Green Real Estate Law Journal also has some coverage but without as much commentary.

**EDIT 07.12.10 - Thanks to alert reader Mara Baum for pointing out that I had the wrong date for the close of registration for LEED-NCv2.2. I had originally listed April 27, 2009, the day LEEDv3 registrations went live. The date LEED-NCv2.2 registrations closed, however, was June 26, 2009, and that is the day the sunset clock started to tick...