NC v2.2 SSc8: Light Pollution Reduction

Most people just ignore directional signage relating to this credit. Any internally illuminated sign would be very difficult to measure. Even if it was measured it would have no effect on the boundary calculations. Uplight would have some effect but not likely to be much in comparision to the large site where directional signage is needed. Advertising or directional signage is excempt from ASHRAE 90.1 so you don't need to worry about the W/sf.

That is the most appreciated information, Bill. Thank you! :-)

The credit talks about interior light leaving the building, not site. And only says interior surfaces count as shields. My guess is this is because light doesn't travel thru glass in a straight line and can shatter if many directions depending on the glass type.

You can try to argue it, and you may have a chance if you can convince them the light doesn't leave the site. But don't count on this credit.

We talked about Residential awhile ago in the NC2009 page on this site. There was no exemption to exclude Residential projects. You'd either have to install auto shades on the windows to close at night, or auto dim the lighting to 50%, or do a complex calculation to show the light leaving the windows is below a certain amount.

Sorry. Seems silly to me too.

Nope. They let projects do this, pick and choose which credit to update, for v2.2 but I've seen nothing that allows it for v2009.

For the first one, other than the typical calculations and photometric site plan, i would recommend some oimages showing the wall. This will give the reviewer a better understanding of the situation.
The second one will definintely need images showing that the neighbors wall does not have any windows or other openings.

I think you'd be fine. I didn't see anything in the Handbook saying the structure had to be owned by the project owner. A solid wall is a solid wall and will shield the light regardless of who owns it.

This is a duplicate post that was in NC2009 also. I am not familiar with Dialux but if it can give output values in a grid format then it should work. I personally use Visual software.

If the lighting is exempt just don't included it in the template. In the narrative explain why you excluded that lighting.

Don't expect to earn this credit. Expecially if the lights are on your poles.

I could see the arguement either way. You could ask for a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide or just try submitting with the extra heads eliminated from the photometric plan. Add a note saying that some city requested luminaires intended for city property have been excluded since they are not part of the scope of this project.

Sorry, they have always taken the position that safety concerns do not exempt a project from this credit's requirements and that not all projects can earn this credit.

Have you extended the boundary to the curb edge of the road and the drive entrance to the center of the road?

I'm not sure if v2.2 projects can go for pilot credits but if all else fails and you have some spare ID credits not being used then it's worth a shot.

Bill, is there a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide where it says that you can extend the boundary to the middle of the road for an entrance? I have been trying to find one. If not, do you know this technique works from experience or from somewhere else? Do you have to use an alternative compliance path?

I just looked for one also. This may just be a v2009 rule because I couldn't find anything in writing for v2.2

Has anyone been able to confirm whether extending the boundary to the middle of the road is acceptable for NC 2.2 / Schools 2007 projects? Have you used this approach and received approval?

If these lights are not included in your EAc 1 calculations, not being replaced, not lighting anything within the LEED boundary, and not part of the scope of work for the project, then i would not include them in my submission. A narrative explaining the situation and that it is just one of those circumstances that does occur, especially on a campus project.

You could also move the LEED boundary if it would not effect any other credit and this would completely eliminate the issue.

I might not understand everything you're asking but I'll do my best. You don't have to show a calc grid on the roof. Just show it on the ground and around the site boundary. It will probably be zero as you suggest but the review team will still want to see something. Just add a note saying that the only exterior lights on the site are on the parking deck at the top of the building. And provide the uplight percentage too. I hope that helps.

It would be where the street begins on your side. even though there is no curb. Just use the edge of the road as your LEED boundary.

If the GF plaza is enclosed you can count the space as interior. If it's just covered by an upper floor then it would be considered an exterior canopy.

Thanks Bill!
Follow up question.
If the covered ground floor is an exterior space, any uplight would be considered to the 5% limit as per LZ3 zone; does the covering provided by the terrace level (i.e. 4th flr slab) to the GF can help with the 5% limit requirement of uplight?

All exterior lighting counts towards the uplight limit.

Any perminant hardscape (not vegitation) can be used as sheilds to limit light pollution, either uplight or spill light. So yes, the 4th floor slab can be considered when calculating uplight.

If the 4th floor slab blocks 100% of light above 90° then it's easy math. If it varies based on how far the light is from the edge of the building then you'll need to determine how much light is shielded for each fixture.

I haven't been able to find any further explanation of what facade area can be counted. I can only go by what the 90.1 standard says, "illuminated wall". If no light from the sconce on the column touches the wall then I would not consider the wall illuminated.

Is your site wattage so tight that 250W will make or break the credit? Did you include the 5% adder? See 9.4.5. The total of the tradable and non-tradable wattage allowance can have 5% added to either category. So, 5,000W of exterior lighting allowance gives you an extra 250W to use anywhere outside. 5,250W total exterior allowance.

If you are still over in your wattage. Now this is a silly situation where adding light may make the site compliant. If you added a few full-cutoff sconces on the wall then you should be able to count all of the wall area below the lights.

Thank you for your quick response. It is close, but that leads me to my next question. Is the 5% adder (for LEED)based on the 5% of the allowable ASHRAE LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. wattages or 5% of the allowable LEED LPD wattages (based on the 20%/50% below ASHRAE numbers).

And, yes, that also was my initial thought that adding on light to a large facade surface area would allow me to comply. Seems kind of contradictory to add light wattage to comply with a credit intended minimize light wattage.

Weird, the pdf on the USGBC website for NCv2.0, 2.1 & 2.2 Rating Systems is no longer available.

I think you meant 80%/50%.

The 5% adder is based on the ASHRAE allowable LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. wattage. Let's see how well I can explain this. Just made up numbers as an example.

You're tradable space allowance is 4,976W and your non-tradable space allowance is 24W then your combined allowance is 5,000W. 5% of this is 250W. You can add this 5% to the non-tradable allowance and have 274W allowable for facade lighting per ASHRAE. Then 50% of this is 137W allowable for facade lighting per SSc8. And 80% of the tradable value is 3,981W for parking lot lighting per SSc8.

ASHRAE 90.1
- 4,976 watts for parking lot
- 274 watts for facade

LEED SSc8
- 3,981 watts for parking lot (80% of ASHRAE)
- 137 watts for facade. (50% of ASHRAE)

80%, yes (I was implying the 20% below ASHRAE).

Ok, great. So the 5% comes from ASHRAE 90.1 but indeed the allowed 80%/50% wattages (3981/137 above) are what applies to SSc8. Thanks!

Ok wait, not so great.

My ASHRAE totals are 19684W Tradeable, 1041W Non-tradeable, therefore to maximize my Facade wattages, I can have 15747 Tradeable and 1038 Non-tradeable for LEED, right?. I have 1184W! Is that correct and does this mean I add a light to a large SF Facade surface area to comply? Kind of contradictive.

Your math looks correct.

Can you use a lower wattage lamp in the lights. You only need about 10% reduction in wattage.

You'll need about 2,000 sf of more wall area.

Not to continue to drag the issue along, but maybe someone else will benefit from this. My original question began with the definition of the facade and the limited square footage and the sconces on the face of the columns causing this issue. What about the thought that the columns are for the walkways (tradeable) and not part of the facade (non tradeable). Realisically they are not much different than a pole light out on a walkway. That would make all the math above a moot point.

If you can defend the arguement that this is a walkway light then it would be possible to claim it as part of the tradable spaces wattage.

It's the facade area, which is illuminated by the fixtures, what counts in the calculation. We have been asked to provide photometric plans to show, what can and can not be applied towards the allowance. These were LEED Cs v3 projects and it was only to determine compliance with ASHRAE 90.1 for exterior lighting.

David,
I was just thinking about this tradable vs non-tradable. If you have excess wattage available in the tradable calculation then you can apply it to any surface. It's "tradable".

In Table 9.4.5 where it describes Non-Tradable Surfaces, at the very bottom it states, "The following allowances are in addition to any allowance otherwise permitted in the 'tradable Surfaces' section of this table.)

Sorry for the confusion.

My head hurts trying to think of how difficult this Credit would be to earn at an airport. Do you really need to earn this credit?

A positive note. I think you can argue that specialized lighting directly related to the operation of the airport could reasonablly be excluded from the exterior lighting requirements. I've also heard of helipad lighting getting an exception.

Per Pilot Credit 7 "Excluded: - lighting for industrial production, material handling, transportation sites, and associated storage areas;"

Now, security lighting cannot be excluded so no extra lights at gates or fencelines. Roads entering will need some sort of dark gap between the road and the drive into the airport.

Meeting the interior light requirements will be easier than v2009 but all of the airports I've been in love throwing light around the interior. Expecially by the ticket counters. You'll have to verify the peak angle of light output hits a solid wall/ceiling/floor, for every light.

I've seen projects earn this point using the campus method and submitting a master lighting plan to eventually bring the entire site with compliance.

If you try this and they accept this master plan strategy then you would only need show the LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. on the area your project covers.

Can a photometric plan be created? Yes,
Can it be printed in a functional way to show grid points 10' apart on a site that is 3,500 acres? I wouldn't want to try. You could export the calculation as a dwg file and try to upload that monsterously large file as the submittal data.

I hope some of this helps. Good luck.

Thanks Bill.

I think interior lighting is OK, just exterior that is a little more complicated.

You said you've seen projects earn this point by submitting a campus master lighting plan to eventually bring the entire site with compliance with SSc8 requirements. So that means every future LEED-certified building on the campus has to meet the master plan. However, does this exclude this particular terminal building from not meeting those requirements? I mentioned that the project-specific LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. and site lumen1. A lumen is a unit of luminous flux equal to the light emitted in a unit solid angle by a uniform point source of 1 candle intensity. 2. A measurement of light output. characteristics does not meet SSc8. If this is unacceptable, does that mean that this and future similar projects on the airport campus will not be able to achieve SSc8?

For light trespass beyond the boundary of the airport campus, perhaps some field measurements at selected perimeter of the the overall airport might suffice?

Thanks again.

The campus master plan example I mentioned was from the Harvard documents posted on their green campus website. It means all future work has to comply. Not just LEED work. If you want the campus compliance method then the whole campus would need to eventually comply with the credit's requirements.

If they accept the master plan strategy then the current project gets a break on the spill light requirements because the boundary has been moved back to the property line rather than the project line. Should be farther away and pretty simple to show it meets the spill light limits.

It does not exclude your current project from the uplight or LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. limits. These still are required. So max of 5% uplight and 80% of ASHRAE wattage.

You can try to apply the exceptions from Pilot Credit 7 to exclude some lights from the uplight calculation.

I doubt they had any intention of regulating airport sites when ASHRAE wrote their standard. In ASHRAE 90.1-2004, 9.4.5, there are various lights that may be excluded from the exterior LPD. A lot of these exceptions will help your airport project. Lights related to transportation sites are excluded. You may be suprised at how low your LPD goes when whole categories of lights are removed from you calculation.

Thanks Bill. This is helpful.

Do Pilot Credits apply for LEED-NC v2.2 projects?

No. But the NC v2.2 credit mentions that "all site and building mounted luminaires" must meet up-light and spill light limits by zone. I think it's fair to argue that transportation related lighting is not the same as "site" lighting. And that you relied on more current information in PC7 to better understand what types of lighting is site lighting and what is considered for other purposes, like transportation or directional marking. Also that these lights were excluded from the LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. so you didn't see them as applicable to include in any up-light calculation. You're just being consistant and making every effort to meet the intent of this Credit.

Most people generally have defined the boundary as the property line. But you were allowed to pick your own project boundary as long as you're consistant between all of the credits.

In connection to above mentioned inquiry is in Dialux software.

I am not familiar with Dialux software. I did a search and their technical support says they cannot do the LEED required calculations. http://forum.dial-gsd.de/viewtopic.php?f=30&t=424&p=698&hilit=leed#p698

Visual software is a free download and can give you the output you need. Like all new software there's some time needed in learning how to use it. Their website does have some instructional material available.

It difficult to verbaly explain how something should look.

We are currently looking into the possibility to use DIALux to comply with SSc8 but also IEQc8.1-2. The reply on the forum that you (Bill) are referring to is dated October 2008; I have sent a new inquiry to check if the latest version supports LEED-calculations. I’ll get back to you in as soon as I get any response

Call the manufacturer again and ask them if you can get a letter (on their letterhead) from them stating what the fixture's angle of peak output is. A bench test from their own shop. It's doens't need to be a full photometric report.

If that doesn't work then I have two ideas.

1) Fixture types have general trends. Most indirect fixtures have similar peak angles. Most recessed fixtures have a peak angle straight down.

Talk to the lighting designer. Find (3) similar fixtures that you can get photometrics for. (Wattage doesn't matter, just how the light is controlled by the fixture.) There'll be some difference between the peak angle but I'd doubt it is more than 15-20%. So this range between the lowest and highest peak angles for these (3) fixtures can be used as a proxy for your fixture. Show that all light output between these angles intersect opaque surfaces. Explain what you did and why in your submittal. I think this would show a valid effort to comply with the intent of the credit.

2) After the fixture is installed, stick a light meter on a stick and hold it next to the light. One yard or meter away is good if possible. If it's close to the ceiling I'd bet only a foot or 30 cm is available. Imagine the center of the fixture as an anchor for the other end of the stick. Keep your distance from the center as equal as possible. Rotate the light meter around in a half circle slowly until you find the peak light level. Measure the angle as well as you can. This is not very accurate but gets you close.

Are light fixtures that are placed further than 3m from the facade visible from outside of the building?

Are the lights more than 3m from the facade more than 50% of the total lights in the space?

If YES to both then it does not appear to meet the credit requirements.

Sorry, I was thinking of the 2009 version of this credit. You will most likely comply with this credit.

The angle of peak output of light from the fixtures must hit a ceiling, floor, or wall. With these fixtures being 3 meters or more from the facade it will probably intersect with the floor or ceiling.

Thank you very much Bill.
Exactly the fixtures intersect with the floor or ceiling. Moreover, all the fixtures in the building have an on/off automatic control. And only fixtures being 3 meters from the facade have regulation depending on the natural light.
Thanks.

Acccording to my knowledge, LEED is considering only within the LEED boundary limit. If Light or landscape, whatever outside the LEED boundary , not necessary to show in the drawing . So you set the LEED boundary then eliminate the objects which is out of LEED boundary.

Sounds questionable to me. I don't think you can just adjust the LEED boundary to give you favorable results on specific credits, particularly if what you're trying to exclude is within your scope of work. Check the Minimum Program Requirements on "gerrymandering."

As you described it this project is not eligable for this Credit.

From CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide's, there are no exemptions for security lighting or other required lighting. Motion sensors don't help.

You cannot adjust the LEED boundary just to ignore some lights. The boundary is the property line or curb line. Sometimes it's the campus property line.

2/16/2009 - Credit Interpretation Request
Our project is an office building located in an area surrounded mostly by residential properties. The office building and site will comply with the Light Pollution Reduction credit.

The firm that will occupy this office building works on many projects of a sensitive nature so security is a significant concern, both for employees arriving early or working after dark and for protection of the facility from intrusion.

Is it acceptable to include motion-sensor activated lights that do not fall within the allowable site lighting wattage? These lights would be located in the immediate vicinity of the building and would only be enabled to turn on when other site lights are off. They would only remain on for a limited time following activation.

If such motion-sensor activated lights are allowed, can they be excluded from the other requirements of this credit, property line illuminance and uplight components, since their purpose is only safety and security?

5/6/2009 - Ruling
The applicant is requesting confirmation if it is acceptable to exceed the lighting power density requirements with motion responsive after‐hours security lighting that is only enabled when the other site lighting is off. Based on the description provided, this strategy is only acceptable provided that when the security lighting is ON, the combined security and general lighting that remains ON, does not exceed the lighting power density thresholds and the security lighting is capable of being controlled to prevent simultaneous operation with the offsetting exterior luminaires.

The second question asks if the lights can be excluded from the other requirements of SSc8 and the answer is no. These luminaires must meet the light trespass requirements relative to their declared environmental zone at the applicable site boundary, as well as the sky glowSky glow is caused by stray light from unshielded light sources and light reflecting off surfaces that then enter the atmosphere and illuminate and reflect off dust, debris, and water vapor. Sky glow can substantially limit observation of the night sky, compromise astronomical research, and adversely affect nocturnal environments. requirements of the credit.

In ASHRAE 9.1.1(c) states that it can be exempted if the areas fall under life safety and second thing is in the LEED page 103 states that light trespass requirments may be met relative to the curb line instead of site boundary. My suggesstion is we can try this to achieve the credit.My understanding is According to LEED/ASHARE states that all projects is not eligible for all LEED credits

1) This should be covered in the LEED handbook. You can use the whole campus as the boundary for this credit but then the whole campus must comply with this credits requirements.

2) USGBC has never allows lights to be omited for safety/security reasons. This credit is optional. They do allow additional light at the property line if the light is required for emergency egress Code reasons. But even then they still require 0.01 fc1. A footcandle (fc) is a measure of light falling on a given surface. One footcandle is defined as the quantity of light falling on a 1-square-foot area from a 1 candela light source at a distance of 1 foot (which equals 1 lumen per square foot). Footcandles can be measured both horizontally and vertically by a footcandle meter or light meter. 2. The non-metric measurement of lumens per square foot, one footcandle is the amount of light that is received one foot from a light source called a candela, which is based on the light output of a standardized candle. A common range for interior lighting is 10 to 100 footcandles, while exterior daytime levels can range from 100 to over 10,000 footcandles. Footcandles decrease with distance from the light source. The metric equivalent of a foot candle is 10.76 lux, or lumens per square meter. at the 10' or 15' line beyond the property line. Which doesn't help much.

3) It's difficult to control light to this extent with short distances involved. Not seeing a plan of the site it's difficult to advise what might work. Have you tried bollards with a shield blocking all light on half of the fixture, and louvers on the other half? Or little LED step lights mounted at 18" in the wall.

As per ASHARE 9.1.1 (c) it can be exempted. The Client and Electrical Engineer & Lighting Designer of the project has to submit confirmation letter for the safety/security reasons. Doesn't required to do simulation for this . This is my suggesstion for you question.