CS 2009 SSc8: Light Pollution Reduction

Vertical footcandlesVertical footcandles occur on a vertical surface. They can be added together arithmetically when more than 1 source provides light to the same surface. is the light you see while standing and looking towards the site.

The Reference guide mentions 10'x10' spacing for calculations. It sounds like some reviewers are asking for the vertical calculations at 5' intervals. That means measured at a height of 0', 5', 10', 15', 20', ..... up to the height of the tallest light fixture.

There is no good way to show a vertical grid on a site for submittal. I've asked for an example but have not gotten one. Another member on this site said they just provided the statistical table showing max, min, and average for the vertical grid and that was enough.

All I've ever shown was a single line at grade. The program I use has an option of "LEED 2.1 Trespass" for grid type. This will show the max value for either horizontal or vertical. It's been awhile since I've submitted and they seem to keep wanting more detail.

I agree with you that it is counterproductive. No LEED credit is worth breaking local laws or endangering people. If the lights are powered from the building and within the scope of this project then I don't see any way to earn this Credit.

I keep pushing people to Pilot Credit 7 since it has lots of excluded lighting. Including government required. This one is a bit more reasonable and you will likely earn it as an ID credit.

The building should at least have a main entrance or other doors into the building. You get a few tradable watts for these doors.

If there really is nothing then try entering a value of "1" into the pdf. Just something so the document lets you continue.

It does not matter if the streets around it have their own illumination system. Ignore any city owned lights.

Any light fixtures that are part of your project need to be included in the calculation.

If the lights are too close to the street then you are not likely to comply with this Credit. You can always look into Pilot Credit 7 as another way to earn a point.

Angelica Maria Grandados Leal comment,
"We are making the documentation required to sustain the credit goes SSc8. The project design is a hotel located a rural area with native vegetationPlants indigenous to a locality (native) and adapted to the local climate; they require limited irrigation following planting, do not require active maintenance such as mowing, and provide habitat value. around. We have designed all the hotel however there is a part and yet we fail to understand is the interpretation of credit with respect to light trespass. We are currently using 3d visual to calculate all exterior, but inside the work uses DIALux. With DIALux we cannot know how much impact the interior light has on the outside. Is there another way to support this? As I recommend addressing this credit? This information is essential to sustain it? Thank you very much."

You do not need to calculate the interior lighting for the light tresspass. Interior lighting is a separate item. You just need to reduce the light leaving the building by complying with either option 1 or option 2.

The exterior lighting options 1 and 2 have nothing to do with interior lighting options 1 and 2. You can pick interior option 1 and exterior option 2, or interior option 2 and exterior option 1. Or 1 and 1 or 2 and 2.

The light trespass calculation only considers lighting outside of the building.

En Espanol
No es necesario para el cálculo de la iluminación interior de la tresspass luz. La iluminación interior es un elemento independiente. Sólo tiene que reducir la luz que sale del edificio por el cumplimiento de cualquiera de las opciones 1 ó 2.

Las opciones de iluminación exterior 1 y 2 no tienen nada que ver con las opciones de iluminación interior 1 y 2. Usted puede escoger la opción y la opción de un interior exterior 2, o la opción 2 y opción de interior exterior 1. O 1 y 1 o 2 y 2.

El cálculo sólo tiene en cuenta el traspaso de luz de iluminación exterior del edificio.

I think "sustain" should mean "earn".

Sorry for the confusion. There is no option 1 or option 2 for exterior lighting.

Is it acceptable to combine Options 1 and 2 for interior lighting requirements? Do one option in in some areas and the second option in other areas?

Yes, you may comply on a space by space method selecting either Option 1 or 2.

Per 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 dated 9/25/2008:

The applicant appears to be requesting clarification for the following questions: [1] can Option 1 and Option 2 of the interior lighting requirements be implemented on a space-by-space basis, [2] are stairwells exempt from the interior lighting requirements, [3] are residential units exempt from the interior lighting requirements, [4] is an open parking garage which is surrounded on all sides by additional buildings associated with the project exempt from the light trespass requirements, [5] are wall fixtures in resident balconies fa╬ade or canopy lighting. The responses to each of the questions are as follows: [1] The proposed approach is acceptable. Spaces are required to either satisfy interior lighting requirements using Option 1 (i.e., minimize light penetration through opaque surfaces) or Option 2 (i.e., install automatic lighting control). [2] The interior lighting requirements may be exempted for fixtures at building entrances and exits per the CIR dated 1/28/08 provided that the fixtures are required for safety. The project team shall submit a copy of the applicable standard with the relevant emergency lightingEmergency lighting as defined by the Illuminating Engineering Society of North America is lighting designed to supply illumination essential to the safety of life and property in the event of failure of the normal supply. requirements highlighted. However, for stairwell lighting to be exempt the output shall not exceed 2 times the code required light level. [3] Residential spaces may not be exempted from the interior lighting requirements. The CIR dated 1/28/08 that is referenced in the request does not specifically address the residential spaces of the dormitory. However, as an alternative for residential spaces, demonstrate that less than 10% of the total lumens emitted by each luminaire are not directly emitted out of the building through any fenestration. [4] An open parking garage that is surrounded by additional buildings associated with the project is not exempt from the ambient light trespass requirements of the credit. Light from the garage fixtures may pass between or over the buildings surrounding the garage depending on the heights and orientations of the parking garage and buildings. Please note that the project documentation must also demonstrate that the interior light trespass requirements are satisfied for covered areas of the parking ramp. Please refer to the CIR dated 12/18/2007 for additional information. [5] If the intent of the wall mounted light fixtures in the recessed covered resident balconies is to light the floor of the balcony then the fixtures would be part of the "canopy/overhang lighting" budget. If the intent is to highlight the walls then they would be part of the "fa╬ade lighting" budget.

Only the area lit by the luminaires.

I know restaurants usually keep the light levels pretty dark during dining hours. But they are required to have quite high light levels for cleaning purposes. (I doubt many actually do this) If you included the supplimental lighting used for cleaning in the total peak light level then the dining hours light levels should be less than 50% of the peak light level. Put the cleaning lights controls as a manual on / auto off with a max 30 minute timer or sensor.

I don't know how a reviewer will respond to this but it's a possible way they could appove it.

Your first and second questions are the same.

ASHRAE 90.1 allows you to exclude advertisement and signage in the power calculation. The sign could be 3W or 300W and it has no affect on your LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. allowance. Hours of use for exterior lights are irrelevant to this credit.

The credit is quiet about how these apply to measuring light pollution. Lately, I've been suggesting to people that they argue these are exempt from the uplight and spill light calculations because they are exempt from ASHRAE and the Pilot Credit. It's reasonable to imply they are exempt here too.

If you want to include them in the calc feel free but it will be extremely difficult finding an IES file to use in the lighting calculation to represent the advertisement sign. And if you can determine the 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. output, assume half of the light is emitted above 90°. The difficulty of modeling signage is why I think the Pilot Credit has excluded it.

Kinda surprised there's no exterior lighting. Zero lot line?

Your neighbors' lighting does not affect your LEED submittal. Your submittal only includes lights in your project boundary.

Thank you Bill, yes, it is a zero lot line project.

Our project has a top that will be lighted, we call it the "crowning" since it is an architecture feature that resembles a kind of crown. Lighting will come from the crowning footing (meaning the crowning base) so all light will face up.

The crowning is a double triangular flat surface that tilts in as it goes upwards. We were thinking about implementing an overhang on top of the crowning to block light avoiding light pollution.

Will this overhang be able to comply with credit requirements?

Thank you.

The facade lighting will count as exterior lighting. And with no site lighting to offset your uplight this design sounds doomed to be over 5% uplight regardless of the canopy or not.

A canopy will help block a lot of the uplight, but not as much as you need. You can try calculating how much of the light hits a solid structure but my guess is you won't get over 95%.

Yes and no. Since this is a Core and Shell certification, what the tenant does shouldn't affect the CS project. But there should be some terms in the contract compelling any tenant to build in a way that doesn't violate CS points earned. Occupancy sensors shouldn't be too difficult for them to add.

Any interior lights that are under the scope of this projects must comply with the interior controls portion/shieldingShielding is a nontechnical term that describes devices or techniques that are used as part of a luminaire or lamp to limit glare, light trespass, or sky glow. of this credit. You can't consider only exterior lighting.

Thanks for your answer, Bill.
In case we have a Tenant Agreement, that they will use light fixtures with a specific reflection cone as to avoid traspassing the glazing facade, would it be ok?

Maybe something worded in the way of:
"If Tenant will normally occupy the space between the hours of 11pm and 5am they shall do one of the following.
a) Install light fixtures so that they are not visible from outside of the building.
b) Lights that are viewable outside of the building shall be dimmed to 50% or less during these hours.
c) Or install automated blinds to close during these hours to block light emission."

Sorry to insist on this, Bill. But I need to get this issue straight.
The project is in Curitiba, Brazil, South America, and there´s no way to assure that tenants won´t work those late hours, because of different time zones with other countries that they may have to work with. It could be something "very unusual", or even "very common", but it won´t be "normal" or "regular". So, from your cuote "if tenant will normally...", may I assume this is not our case and there´s nothing to worry about?
Second question (should the above be not so): "installl light fixtures not visible from outside". I don´t see how the fixtures themselves may not be visible from the outside, through glass shield. Would this instead reffer to the projection of the light cone, that it won´t be visible from the outside, that is, the light emmitted by the light fixture?

I have not heard of any official ruling saying how often people have to work for it to be considered normally in use. I have no affiliation with USGBC so I can't give you more information than what's available publicly. You can try 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 but I don't think you'll like the response. They'll probably say if you can anticipate people working at late hours then dimming or sheilding should be done. In my submittal of EQ8.2 I was told that once a month use of a room still means that room is a "regularly occupied space". So try not to rely on logic too much.

Being a Core and Shell project should give you some distance from actions that Tenants might take. Tell the tenants they should have occupancy sensors set at a max of 30 minutes for situations where someone might work late. Or recommend bi-level switching of fixtures so that half of the lamps are off at night. If it's a 2-lamp fixture then have it switched so 1-lamp is off at night. Or every other fixture. People probably won't need full light at night. Might also avoid messing with their Circadian rhythmThe rhythm of an organism's vital functions with relation to the daily cycle of the natural environment. too much.

The light cone your refering to I think was from an older version of LEED. That was based on the peak angle of output. Now it's just viewable. Fixtures with a "direct line of sight" outside means just about every light fixture within 15 meters from the windows. Maybe more. An exception would be deep cell parabolic troffers, but who want's to work in an office with these. ick. I'm not a fan of this part of the credit. I think it was added because of the Henry Gifford paper 2 years ago with a photo of a LEED building in NYC glowing at night from all of the interior lights. I think requiring 30-minute occupancy sensors is fine, but that's just me. I'm a big fan of 'keep it simple'.

I think if you add something like the language I suggested in your tenant agreement it covers this project for this point.

I know wasn't exactly your question, but it would be helpful to hear some more details on the debate of LZ-2 vs. LZ-3 fory our project.

It would help to know more about why you think your project should be LZ-3.

Usually most projects have submitted under LZ-3 and no one has ever questioned it. I've had my own personal doubts often because I always felt most projects like college campuses should be LZ-2. It seems the reviewers are getting more strict. They'll push you into LZ-2 unless you can convince them it doesn't fit. Who is drawing the line between what is light commercial/industrial and what is commercial/industrial? If it's not defined then how can you prove your point? It's your word vs the reviewers.

I've always preferred absolutes in Code like language. I kinda wish this credit was based on zip code and population density. Or City Zoning districts. It's not perfect that way but at least the professional knows what to expect. How does it make you look telling the customer you may not earn this credit because of a difference of opinion on what is a commercial district.

I think these are the definitions from the standard rp-33

3. Lighting Zone (LZ2) – Areas predominantly consisting of residential zoning, neighborhood business districts, light industrial with limited nighttime use and residential mixed use areas. Lighting may typically be used for safety and convenience but it is not necessarily uniform or continuous. After curfew, lighting may be extinguished or reduced as activity levels decline.
4. Lighting Zone (LZ3) – Areas not classifiable under the other four Lighting Zones. Areas of human activity where the vision of human residents and users is adapted to moderately high light levels. Lighting is generally desired for safety, security and/or convenience and it is often uniform and/or continuous. After curfew, lighting may be extinguished or reduced in most areas as activity levels decline.

Thanks, Bill and Tristan, for your comments. Our project is in a suburban commercial office park. To it's west and south there are a whole bunch-- 20?-- of 2-10 story office buildings. To it's east there is a single family residential neighborhood. To it's north is a light industrial area. (Yes, I know, typical Houston!)

I think I will argue that it is in a neighborhood defined as "urban" by the 2000 census. The tract it is in contained 1342 persons per square mile in the 2000 census, and that was before the vast majority of this office park was built. This is the evidence I am using for that: T:\2009080\01_SS\SS8_ Light Poll Reduct\77041 5-Digit ZCTA, 770 3-Digit ZCTA by Census Tract - TM-P002_ Persons per Square Mile 2000.mht. It's from the US Census Bureau American Fact Finder.

Let us know how that works.

I've been meaning to reply to let you know that our review team accepted the argument I made with respect to our project being in a Census-defined urban area, therefore appropriately categorized in LZ-3. They made no comment other than "the documentation demonstrates credit compliance."

You are correct that you cannot count the credit twice.

Pick the one that helps you the most. If your canopy is only 20 sf and the door is 3' wide then going with the 20W per foot of door gives you 60W rather then the 25W allowed by the canopy calculation.

Remember you get a 5% unrestricted allowance for the site that can be applied anywhere. Just in case you want an extra bright main entrance.

Covered parking is considered interior lighting with an allowance of 0.2 W/sf. Most of the lights seem like they would be shielded by building structure.

USGBC has never allowed additional lighting for security purposes. Either shield direct line of site for these lights or dim them.

One idea is to add occupancy sensors all over and when they sense someone the lighting can increase to full brightness. This is not a simple solution since many sensors don't like winter conditions or vandalism and getting good sensor coverage in a garage is difficult. I think it's easier to reconsider lighting placement and type.

Interior or exterior?

for Interior, ASHRAE 90.1 does not list a building type similar to this. In my opinion the closest building type is Manufacturing facility at 1.3 W/sf. It may be better to do the space-by-space method. Electrical spaces get 1.5 W/sf

for Exterior they're all the same. It's based on parking lot size, sidewalk length, building facade.

An electrical substation seems like an odd building type to go for LEED certification.