Code required site lighting

Bill,

I'm to sure I really understand your questions and comments, but I'll give it a shot.

The thought was that you should be able to meet the lighting requirements of life safety codes, specifically exit discharge lighting, AND meet the requirements of the credit. The lack of the exemption does not prevent meeting life safety code requirements or providing lighting for the "safety and comfort of building occupants".

For previous versions of this credit this exemption may have been needed because on projects with project boundaries at the curb and building exits directly onto the sidewalk it might be impossible to provide code required exit discharge lighting without violating the credit trespass limits. With the new "Lighting Boundary" approach, this is unlikely to be a problem.

Nice analysis, but if I may critique it I'd say this. If the objective is to meet life safety code required minimum light levels to light the exit discharge, which in this case would be the area of the sidewalk in front of what we assume is an exit door with the fixture above it, then I'd say that you have much more light than is needed. So reduce the output of your fixture and you will probably meet the trespass limits. Granted, when the lighting boundary is 10ft. from the face of the building, it is going to be tough. The other way to approach this would be to use the BUG option. No one is saying that light trespass control is more important than life safety. There may be extreme cases where it is impossible to meet life safety code requirements and meet the credit requirements. So in that case life safety trumps and you don't get the point.
The credit is optional, it is not a prerequisite, and LEED is not mandatory code. Or you write a narrative and make the case that you have done everything practically possible to control light pollution and meet life safety code requirements.

Regarding your second comment: Are you saying that if the lighting boundary is the centerline of the public roadway, you can’t properly light the of the driveway? I don’t see that. Can you explain?

Bill,

All I was saying is that if you have 2.38fc VERTICAL at 10ft. from the door, then you probably have WAY more than 1fc HORIZONTAL on the sidewalk, which is generally what you would need for egress code at the discharge. So I don't think you'd need a 2x26watt fixture to meet code. That's all I'm saying. FYI, there are CFL lamps as small as 7-watts, although typically the smallest you might use in a fixture like this would be 13-watts. Or maybe a small LED fixture.

I hunted around for the sample site plan you mentioned but can't find it. Maybe you can post a link. The 100-watt fixture 60ft. from the center of the road on a 20ft. pole seems arbitrary. The exercise should be to light your driveway to minimum IES recommended levels and then either run the calc or look at the BUG rating of the fixture. Then see if you pass, and if not, see if you can by adjusting pole location, height, fixture output, etc.

Spill light in the public roadway IS OK. That is the whole reason that the Lighting Boundary concept was developed and why it can be in the centerline of the road (you get half the road, the guy across the street gets the other half - that's the idea). It's certainly a lot more sensible than the way the credit is now in 2009, right?

Spill light into private property or protected natural areas IS a problem and something the credit controls. Everyone has the right to, and need for, darkness at night.

The issue of code requirements conflicting with credit requirements being contradictory with the USGBC mission statement is something best answered by USGBC staff. Speaking for myself, I'd say that the credit is designed to encourage the minimization of light pollution. If the credit allows excessive light pollution then it is not serving its purpose. The intent was that projects should, in general, be able to simultaneously meet credit requirements and life safety code requirements. But some projects just aren't going to be able to get the credit, and if they don't control light pollution, then they shouldn't. Isn't this the way it should be with all LEED credits?

Bill,

So, should we just conclude that we should use the BUG method for your exit discharge example? Meets credit requirements and you can use the 2x26-watt fixture? No problems?

Regarding the "need" for darkness, I refer you to the following:

http://docs.darksky.org/Docs/ida_human-health_brochure.pdf

http://docs.darksky.org/Docs/ida_wildlife_brochure.pdf

And personally I believe that you should ideally be able to sit in your backyard and enjoy the darkness, and just the light from the moon and stars. It's like noise pollution. I should be able to sit in my backyard and enjoy the quiet and just the sounds of nature. I don't think it is right to assume that if someone is outdoors at night they are going to have the lights on, any more than you would assume that if they are outdoors they will be making so much noise they don't mind the neighbor across the street revving his motorcycle.

I'm not sure if you are saying that light trespass is not a problem, or if you are just questioning how it should be defined and where the "line" should be set where trespass is measured. If the later, then you have hit upon a complex issue. In general, the approach with light pollution control standards has been to use the property line, with the idea of protecting the private property rights of the owner or the neighboring property regardless of their uses of their property. But with, for example, a commercial office building, where no one is sleeping or spending anytime outdoors except going to their cars, you could argue that light trespass causes no problems. Of course to write a standard that takes all kinds of property types and uses into consideration would be very complex. The LZ concept does sort of address this - you can't expect darkness on your apartment roof-deck in the middle of the city, but in the backyard of your farmhouse, you can.

Regarding the issue we have been discussing when you have a public roadway between two private properties, it is certainly debatable where the lighting boundary should be placed. The consensus of the SMEs was that it should be in the middle of the roadway, but I recall there was some discussion of placing it at the property line of the property across the street. Either way, it is certainly an improvement over SS8 in LEED-2009. (also note that the lighting boundary definition is consistent with MLO, IgCC, 189.1 - there is something to be said for consistency)

The 30ft. above highest fixture requirement is based on the idea that you could have a tall building adjacent to the subject property that would be looking down on the site. This comes from the performance method in the MLO. I agree that it is unlikely that you are going to get higher levels on the grid above the highest fixture, but there are probably some scenarios where it could happen. It really isn't any more work to run the grid up higher. Or just use the BUG method.

Regarding your comments on pedestrian/vehicle conflict safety, I believe that in principle the credit should not prevent the lighting of sidewalks and driveways according to IES recommended practices. (Note that the BUG method and the "lighting boundary" are in the MLO which is a document jointly developed by the IES and the IDA, so the assumption is that the IES isn't going to write light pollution control standard that prevents you from meeting their own recommendations.) The tricky area has always been where a private drive intersects a public roadway and there are sidewalks and pedestrian activity. But I contend that It is not the LEED project's responsibility to light the intersection, rather it is the municipalities. It would be great to run some models of this condition for various LZs and sizes/types of roadways, lighting the driveway and roadway and intersection to IES minimum recommend levels and uniformities.

The SMEs and staff worked very hard to IMPROVE the credit - to make compliance much simpler (BUG method) and to fix quirks in the credit that prevented perfectly good designs from meeting the credit requirements - but still have a credit that would control light pollution, and a credit that did not inadvertently allow excessive light pollution. In this conversation I'm just trying to explain the concepts and background behind the credit as best as I understand them. So please don't shoot the messenger.

Bill,

Well, it looks like we'll have plenty of time to get this hashed out. I do want to counter a few misunderstandings.

You mention an "obsession with matching the MLO". If such an obsession existed then what you call the "alternative" - which is basically the current method - would have been deleted altogether. I think the consensus was that it would be too radical to convert exclusively to a new method that had not been widely tested with real-world projects, even though that method (BUG) had been developed over a 6-year period with tons of work from lighting and light pollution experts and the endorsement of the IDA and the IES. The current method is still there just for people like you who are more comfortable with it, or prefer a performance rather than a prescriptive method. Because of the two options, the new credit "looks" very complicated, and we received flack for that, but stuck with the two optional methods.

You may not like the BUG method, but it has the huge advantage of not requiring any computer modeling. Some have argued that the current method is flawed because it requires lighting computer modeling and significant lighting expertise to comply with, and this discourages projects from pursuing the credit.

The IES does not "control the credit" - they have zero involvement with credit development and have not been pushing for use of the MLO in LEED. And you are NOT wasting your time commenting. I encourage you to submit constructive and clear comments the next time around. And please participate in “beta testing”.

And you are right-on about the reference guide. It is key, and has been a weak link in the past. The new light pollution credit will fall on its face without a good ref guide.

Bill,

You seem to be seeing a conspiracy where there wasn't one. And even if there was, what you say doesn't make sense to me. IES is also one of the developing organizations of ANSI/ASHRAE/USGBC/IES Standard 189.1.

Hi Bill,
We actually have modified the Light Pollution Reduction credit in response to your comments (submitted through both the USGBC Public Comment process and LEED User). Specifically:
1. We did not have an exemption for National Flag lighting, but in response to your comment, we included this exemption starting in the 3rd Public Comment draft; 2. We revised the BUG tables to fix errors, per your suggestions; 3. We provided a height for the boundary calculation grid, as you suggested in the 1st public comment period; and 4. We clarified signage requirement compliance (how luminance data is to be provided for conventional backlit signs) based on the issue you raised in September of last year.

We take the public comments very seriously, and we do respect and value the expertise of our stakeholders. We have not simply rejected comments because they don't help our "opinion." Rather, we have had multiple long discussions as a group over the last year+ about the comments and considered all of them when writing the credit. And as you can see above, we have revised the credit based on your input.
Thank you!

Bill,

I'm assuming that your last two comments were directed to USGBC staff, not me. I don't work for the USGBC.

Bill,

In my experience, SME's do not have the kind of authority or unified opinion that you attribute to them. Although influential on the content (isn't that the idea?) we are not "in charge of developing this credit". I appreciate your frustration with the development process, but it’s the USGBC that defines and controls the process, not me. Please address your concerns with the development process to the USGBC, not me.

Hi Bill -

I can answer your question - I assist in the management of the overall LEED v4 program , with particular focus on ensuring consistent development through the consensus process, which involves our volunteer committees, public comment, consensus body and ballot.

Our development process is simple and completely overwhelming at the same time. We open our substantive changes up for public comment, consolidate that feedback based on credits and expertise areas, and provide it to our technical experts (internal to staff and external volunteers) to review. These small groups (sometimes loosely referred to as SMEs) discuss in the context of a number of issues [technical feasibility, market acceptance, organizational mission, international applicability, relation to our LEED Impact Categories, cost & time to implement, simplicity for the user, appropriate for inclusion in rating system vs. ref guide, credit achievement, and so on], and provide responses, making a change to the rating system language only if appropriate. Multiply this by the over 20,000 comments received over the course of the past four comment periods, and you've got more than enough work to go around. :)

All of our proposed changes - which are provided to our users for a subsequent public comment period - as well as the responses to all of our public comments are approved by our LEED Steering Committee. The Steering Committee is an integrated group of staff and volunteers who ensures the integrity of the LEED system and - in the case of rating system development - ensures that the changes proposed over time are consistent with the direction provided to each group in terms of objectives and priorities for the v4 update to LEED.

Subject Matter Expert (SME). Technical Advisory Group (TAG). Core-Committee Members. Take your pick. The final control over the LEED development is none of these.

What many people do not realize about LEED is that once a requirement is "invented" it is nearly impossible to remove it. Regardless of whether the requirement is an error in interpretation.

Any uplight is bad. Surface reflected light you can have all you want.

Flag lighting was not the specific issue as it was ZERO uplighting being determined as the hard requirement for SSc8 in LEED v2.0. Ever since then, the uplighting restriction has been hardcast in LEED. Flags, everygreen trees, facades, anything.

Flag lighting has been a sore point since it was "invented" by the Reference Guide authors. It was not developed by the person responsible for the development of SSc8 for LEED v2.1, David Nelson (SME). For LEED v2.0 there were mo SME's. There was a single firm that read standards and made up the rules.

Although, flag lighting was deemed okay, it was deleted by the the v2.1 Reference Guide authors as contradicting what they originally developed. If the requirement was there in 2.0 then it must remain for v2.1, etc. Ten years later and still, flag lighting is a sore point.

The TAGs and SMEs don't invent things like vertical grid calculations. Those get invented either as part of the Reference Guides or the Certification Review process.

The inventor appears to be the USGBC's LEED Department, and the outside consultants they hire to assist with rules development.

At some point in time, one of the rules writers decided to change the requirements and the LEED Department rubber stamped it. The reason for a change like this is, "oops, we forgot something." In this case that something was to limit light pollution to the exceptions were allowed.

Uplighting is controlled by the requirements. Check!

Boundary footcandles are controlled by the requirements. Check!

The a discussion between rules inventors occurs, something to the effect:

"Opps, what about the boundary envelop?"

"The What?"

"The boundary envelop implied by the credit."

"There is nothing about a boundary envelop in the credit."

"It is implied. We must control all light in the envelope. What if someone points a laser light above the ground level and below horizontal? They would be cheating the credit."

"Okay, I see. Yes, lets add it. The envelop restriction is implied. We do not need TAG, Steering Committee or Membership approval."

"Okay, a vertical calculation grid is now required, and should have been required since LEED v2. Now we can enforce on all projects. Those that have ignored the new requirement can slide. Everyone else must immediately be held responsible for the new requirement that has always been there."