Addressing both interior and exterior lighting, this credit seeks to reduce light pollution that can block our view of the night sky and cause human health problems as well as ecological problems for many birds, insects, and other animals. Light pollution often represents nighttime lighting that isn’t needed and that may cause light trespass and contrast, reducing visibility.
Many people think that more lighting means better nighttime safety and security. However, too much exterior lighting can make outdoor and parking areas less safe by creating high contrast between lit and unlit spaces. Among other problems, when the human eye is flooded by bright light, it becomes harder to adjust to darker areas and shadows. Too much exterior lighting also means unnecessary energy consumption. Some objectives to keep in mind when striving for safe, efficient, and aesthetically pleasing lighting design are lighting uniformity, low contrast, no glare, and preventing light from spilling off the site. This can be achieved through judicious selection of fixtures with full cutoffA full cutoff luminaire has zero candela intensity at an angle of 90 degrees above the vertical axis (nadir or straight down) and at all angles greater than 90 degrees from straight down. Additionally, the candela per 1,000 lamp lumens does not numerically exceed 100 (10%) at an angle of 80 degrees above nadir. This applies to all lateral angles around the luminaire. that direct light toward the ground but prevent it from shining up into the night sky.
Light pollution reduction is a simple credit to achieve if you use a building automation system (BAS)A building automation system (BAS) uses computer-based monitoring to coordinate, organize, and optimize building control subsystems, including lighting, equipment scheduling, and alarm reporting. to control lighting. If not, compliance with the credit can be more complex, but not necessarily very expensive. If you don’t already have automated controls or occupancy sensors for interior lighting, or a design in which light fixtures aren’t directly visible from the exterior, the requirements for interior lighting can be fairly challenging to meet. However, only non-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. that has a direct line of sight to an opening in the building envelope needs to be automatically controlled.
Fully-shielded exterior lighting will direct light downwards while eliminating light trespass to the night sky.
This credit offers three different rules for analyzing your existing interior lighting to figure out whether each fixture meets the direct-line-of-sight requirement. The rules can be confusing, however, and completing this analysis doesn’t necessarily guarantee that you’ll comply with the credit requirements. On the other hand, the requirements for exterior lighting requirements are comparatively straightforward and cost-neutral in most circumstances.
To achieve all aspects of this credit, carefully assess existing conditions and determine what, if any, alterations to the existing lighting fixtures and controls are necessary. Use of an existing building automation system that controls interior lighting will give you the best shot at this credit.
Exterior fixtures with occupancy sensors cannot be excluded from the shielding requirements if pursuing Option 2.
The following CIR provides guidance for similar situations within the LEED-NC rating system but specific guidance for LEED-EBOM projects has not been provided by USGBC. The following CIR has not been assessed for applicability for the LEED-EBOM rating system.
12/18/2007 - CIRThe applicant is seeking clarification as to the interior/exterior area classification for a four level open air parking ramp building. For the purposes of SSc8, parking structure covered floor area is to be considered interior area and uncovered area is to be considered exterior area. Thus, any lighting within covered area must meet the interior lighting requirements of this credit and any lighting within uncovered area must meet the exterior lighting requirements of this credit, including being below specified foot candles horizontal and vertical at all locations outside the boundary of the property.
LEED has provivded no specific guidance for this scenario, but here are some options to consider:
Page 71 of the LEED-EBOM v2009 Reference Guide outlines a path for Option 3 to comply with the maximum footcandle levels prescribed by IESNA RP-33.
If you already use automatic interior lighting controls in your building:
If interior lighting systems are not controlled automatically, assess the level of effort required to integrate automatic controls into the interior lighting system.
Interior lighting that does not have a direct line of sight to the building envelope is exempt from the credit. Three sets of exemption guidelines are detailed in the LEED Reference Guide which explain how to measure the distance and angle of lighting fixtures from windows to determine if any of your fixtures may be excluded.
Include seasonal adjustment of the automatic control schedule to maximize energy savings and reduce light pollution.
Integration of automated controls into interior lighting systems may require a range of low-to-moderate investment depending on the level of implementation required. However, installation of automatic controls typically gives a favorable payback period of 2–4 years and energy savings of up to 40%–50%.
Occupancy sensors may be the easiest and most cost-effective way to satisfy interior lighting control requirements in buildings that do not currently have automatic controls for perimeter spaces.
Choose the most advantageous of the following three options. When possible, Option 1 is easiest, and Option 2 is generally simpler than Option 3.
Documentation is streamlined for LEED-certified projects. If the project is certified under LEED-NC or LEED for Schools, show that SSc8: Light Pollution Reduction was earned. If the project is certified under LEED-CS and 75% of the floor area is LEED-CI, show that SSc8: Light Pollution Reduction was earned for both systems.
For buildings with exterior lighting that has appropriate shielding, it is probably simpler to show compliance with Option 2 than to perform the perimeter illumination measurements required for Option 3.
Option 2 requires partially or fully shielding all fixtures 50 watts and over so that they do not directly emit light to the night sky.
Start by completing an inventory of all exterior lighting fixtures to determine fixture shielding and find which fixtures need to be altered.
Modify fixture shielding where necessary and minimize illumination of architectural and landscaping features.
Exterior lighting systems includes any and all lighting on the project site, including parking lot lighting, illuminated walkways, architectural lighting, signage, and flagpole lighting.
Fixtures are considered adequately shielded if the lower edge of the shield is at or below the centerline of the light source or lamp.
When considering changes to exterior lighting design or intensity, collaborate with building staff in charge of safety and security, to ensure that lighting continues to meet those needs. Reducing light pollution can go hand-in-hand with improving safety, by reducing glare and high contrast that is often associated with overly bright lamps with widely dispersed light.
When replacing fixtures, fully shielded fixtures can generally be specified with no additional cost premium. It may be possible to retrofit existing fixtures with compliant shielding to prevent the need for complete fixture replacement.
Replacement of high-wattage lamps with low-wattage, lower-lumen alternatives can eliminate the need for shielding to meet credit requirements. For instance, LED lighting that is less than 50 watts may be sufficient for directional lighting in exterior situations.
Costs will vary depending on the number of fixtures or lamps that must be retrofitted or replaced to meet the shielding requirement. Reducing wattage may be less expensive in some cases than adding shielding.
Measure the night illumination levels at regularly spaced points around the perimeter of the property, taking the measurements with the building’s exterior and site lights both on and off. The building’s interior lights must be in the same state during both measurements.
Minimize light trespass at the LEED project boundary, and develop a plan for performing required measurements during the performance period.
Redirect exterior lighting wherever possible to direct downwards rather than upwards to reduce night sky illumination.
Remove unnecessary lighting of architectural and landscaping features.
Facilities staff can perform these modifications, making costs minimal.
Confirm that automatic controls are properly managing interior lighting.
If manual overrides are available for occasional after-hours use, check that lighting system controls are restored to normal shut-off schedules following any overrides.
Work with custodial staff to ensure that control systems are reactivated appropriately following an override situation.
Compliance for this option is low-to-no cost.
No action is needed during the performance period for compliance with this option.
Adhere to a preventative maintenance program to regularly inspect exterior lamps, fixtures, and shielding to ensure minimal levels of light pollution.
As a best practice, use manual or automatic controls to turn off exterior lighting during late-night hours when reduced lighting will not create a safety risk.
A preventative maintenance program will likely involve no or low costs.
Record night illumination levels at the site perimeter to determine the level of light trespass and adjust lighting strategies accordingly.
Be sure to perform measurements after twilight in the evening or before twilight in the morning, based on the U.S. Navy data (see Resources) for your location and testing date.
Cost range will depend on whether testing is performed by in-house staff or a third-party consultant. Costs are minimal if testing is done in-house.
Excerpted from LEED 2009 for Existing Buildings: Operations & Maintenance
To minimize light trespass from the building and site, reduce sky-glow to increase night sky access, improve nighttime visibility through glare reduction and reduce development impact from lighting on nocturnal environments.
Project teams must comply with the interior lighting requirement AND 1 of the 3 options for exterior lighting.
All nonemergency built-in luminaires with a direct line of sight to any openings in the envelope (translucent or transparent, wall or ceiling) must be automatically controlled to turn off during all after-hours periods during the performance period. The total duration of all programmed after-hours periods annually must equal or exceed 2,190 hours per year (50% of annual nighttime hours). Manual override capability may be provided for occasional after-hours use.
Implement a program to ensure that the lighting control system is being properly used to adjust lighting levels during all after-hours periods.
If the project is certified under LEED for Schools or New Construction, show that SS Credit 8: Light Pollution Reduction was earned. If the project is certified under LEED for Core & Shell Development and 75% of the floor area is LEED for Commercial Interiors, show that SS Credit 8: Light Pollution Reduction was earned for both systems.
Partially1 or fully shield2 all exterior fixtures 50 watts and over so that they do not directly emit light to the night sky.
Measure the night illumination levels at regularly spaced points around the perimeter of the property, taking the measurements with the building’s exterior and site lights both on and off. The building’s interior lights must be in the same state during both measurements. At least 8 measurements are required at a maximum spacing of 100 feet apart (30 meters), so as to be representative of the illumination levels at the perimeter of the property. The illumination level measured with the lights on must not be more than 20% above the level measured with the lights off. This requirement must be met for each measurement point; averaging of all points is prohibited.
Adopt site lighting criteria to maintain safe light levels while avoiding off-site lighting and night sky pollution. Minimize site lighting where possible, and use computer software to model the site lighting. Technologies to reduce light pollution include full-cutoff luminaries, low-reflectance surfaces and low-angle spotlights.
IES correlates research, investigations, and discussions to guide lighting professionals and lay persons via consensus-based lighting recommendations.
Provides a description of the outdoor lighting zones developed for use in the 2005 California Energy Efficiency Building Standards (Title 24).
This nonprofit agency dedicated to educating and providing solutions to light pollution.
Use this U.S. Navy website to determine twilight parameters for taking site illumination measurements.
Demonstrate compliance through outdoor fixture 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. as documented through manufacturer cutsheets.
Use scale drawings to show the project boundary and the location of all illumination measurement points around the boundary. Maintain records of measurement protocols and data points.
The following links take you to the public, informational versions of the dynamic LEED Online forms for each EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems.-2009 SS credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.
Version 4 forms (newest):
Version 3 forms:
These links are posted by LEEDuser with USGBC's permission. For more information, visit LEED Online and click "Sample Forms Download."
I've been reading the EB&OM stress test, and felt confused about the "multi-tenant difficulty" factor in SSc8. What does it mean?
Jun, if the building has a number of tenants you'll have to coordinate with all of them to meet the interior lighting requirements, for example, and that might be relatively difficult—or it might not, depending on the project. The factor is mentioned as a rule of thumb, not an absolute.
All exterior lighting was retrofitted to CFL1. Compact fluorescent lamp (CFL) light source in which the tube is folded or twisted into a spiral to concentrate the light output; CFLs are typically 3 to 4 times as efficient as incandescent light bulbs, and they last 8 to 10 times as long.
2. Small fluorescent lamps used as more efficient alternatives to incandescent lighting. Also called PL, CFL, Twin-Tube, or BIAX lamps. (EPA)
3. A light bulb designed to replace screw-in incandescent light bulbs; they are often found in table lamps, wall sconces, and hall and ceiling fixtures of commercial buildings with residential type lights. They combine the efficiency of fluorescent lighting with the convenience of standard incandescent bulbs. Light is produced the same way as other fluorescent lamps. Compact fluorescent bulbs have either electronic or magnetic ballasts.'s a few years ago and is below 50W. Do we still need to perform Option 3 and take measurements?
Aron, I would follow Option 2, and note that there are no fixtures over 50W, and thus all 50W+ fixtures are shielded. This allows you to check the box on the LEED Online form stating "All exterior fixtures 50 watts and over are partially or fully shieldedIn a fully shielded exterior light fixture, the lower edge of the shield is at or below the lowest edge of the lamp, such that all light shines down. so that they do not directly emitlight to the night sky."
Am I totally confident that this is correct according to GBCI? No. But I say it meets the intent and is solid as far as documentation. Let me know what you think—or anyone else, please chime in.
If you follow Option 2, you do not need to perform Option 3.
This LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. is similar to your situation.
6/1/2009 ID# 2556
Fixtures less than 50 watts are excluded from the 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. requirements for EB O&M SSc8 Exterior and Site Lighting Option B. Buildings with no exterior or site lighting fixtures at 50 watts or more would also meet the requirements for SSc8 Option B. This project would be eligible for EB SSc8 Option B only if the unshielded accent lights were completely replaced by ... fixtures that are less than 50 watts before the start of the performance period and SSc8 interior lighting criteria were met as well. Applicable Internationally.
Hi, our site have an area which lighting system is operating 24/7 in order to support the factory which also operates 24/7. So, can us not add this specific area into the table SSc-8
No. Either you'll need to add automatic shades that cover the windows between 11pm and 5am or the lights will need to be installed so they do not shine any light directly thru a window.
The Reference Guide is rather vague on how a manual override should be returned to normal saying just “Manual override capability may be provided for occasional after-hours use. Implement a program to ensure that the lighting control system is being properly used to adjust lighting levels during all after-hours periods.” We have submitted a project that uses their night cleaning staff to restore any manual overrides after-hours. In the LEEDuser checklist section above, the following advice is given: “If manual overrides are available for occasional after-hours use, check that lighting system controls are restored to normal shut-off schedules following any overrides. Work with custodial staff to ensure that control systems are reactivated appropriately following an override situation.” However, we just received the project back from the preliminary review with the credit marked as “Pending” with the following comment: “Restoration to normal shutoff schedules after a manual override must be automatic rather than manual.” Any advice on how to address their comment would be greatly appreciated.
"Implement a program to ensure that the lighting control system is being properly used to adjust lighting levels during all after-hours periods.”
-- This means someone needs to make sure the controls haven't been disabled or otherwise monkeyed with.
“If manual overrides are available for occasional after-hours use, check that lighting system controls are restored to normal shut-off schedules following any overrides."
-- This is talking about how people monkey with the settings. They might not like the 30 minute shutoff and open it without permission and dial it to it's maximum setting of 90 minutes. This is telling the maintenance staff to recommission the controls to make sure nothing is longer than 30 minutes.
" Work with custodial staff to ensure that control systems are reactivated appropriately following an override situation.”
-- This says to verify if you use an override control that it doesn't mess up it's normal control schedule. If I push the override at 2am and it times out after 30 minutes, make sure it doesn't mess up the scheduled 'on' function that happens every day at 7:30am.
The controls have always needed to be automated for this credit. I find occupancy sensors to be the easiest form of compliance. Set the time delay to 30 minutes or less.
[ignore]How are you complying with the requirements in ASHRAE 90.1 for EAp2. Item 188.8.131.52 requires automatic lighting shutoff.
Ignore the last paragraph. I was thinking about LEED-NC projects.
The second item on the LEEDuser checklist that you read thru said this.
-If interior lighting systems are not controlled automatically, assess the level of effort required to integrate automatic controls into the interior lighting system.
Thanks for your fast reply and for the clarifications! I think motion detector timers will be the way to go with this building.
I dont understand how to document a compliance with the interior lights. I can take photos?
Photos or plans can be used to document locations where interior lights have no direct line of sight outside.
For lighting that has a direct line of sight outside the LEED-Online form has a table for you to fill out. List each zone or room and then the total night time hours the lights were turned off during your Performance period.
Then write a description of what automatic controls are being used to keep the lights off at night and that there is maintenance to make sure the system keeps working.
For our project we did a night illumination plan but off-site lights (public street lights) were causing our measurements to be over 20%. any idea how we can reconcile this difference?
How many points don't comply? Why do you think the off-site lights caused this? Did the street lights turn off halfway thru? More info would let me be more helpful.
You should try to make everything else as equal as possible for the two measurements.
1. Your interior lights are the same. (either on or off)
2. Your neighbor's exterior lights are the same. (either on or off)
3. The sky is dark. Start an hour after sunset to make sure a glowing sky at dusk doesn't mess with your readings.
4. Mark your locations to make sure you're measuring the same spot.
5. Hold the sensor the same way.
If the public street lights were on for both of your measurements then I'd say your own site lighting was the cause of the 20% difference. Which is a situation this credit was designed to catch.
If one point is causing an issue try shifting your measurement points. If several points are an issue I doubt you can earn this point.
The only exterior lights on the building we are working on are historic light fixtures at the entrances to the garage. Although the fixtures are 175 watts and are not partially or fully shieldedIn a fully shielded exterior light fixture, the lower edge of the shield is at or below the lowest edge of the lamp, such that all light shines down., they are on motion sensors so they only turn on when a vehicle is approaching the entrance to the garage. The building is unoccupied at night so it is unlikely that the lights would even turn on. This seems to meet the intent of the credit but I am not sure how to document it.
They don't seem to make exceptions for lighting on occupancy sensors.
The only way I can see Option 2 work is relamping the fixture. I'm guessing it's a 175W incandescent since it can turn on instantly with the sensor. I've been impressed with LED technology over the last 2 years. A 49 Watt LED replacement from a quality manufacturer will give the same amount of light output.
Or Option 3. You can take measurements up to 100' apart. Try strategicly placing these points where it will help you the most. Measure 50' to either side of the centerline of the garage entrance. That's what I would try.
I have seen some projects with historic light fixtures that have them modified to keep the same general appearance but significantly reduce the uplight and glare. If you got the money.
Has anyone documented Rule 3: Angle Exemption?
I'm confused by the diagram in the reference guide. It is a plan view, correct? It seems like any recessed fixture should be exempt, but apparently this is not the case.
Does rule 3 mean that recessed lighting fixtures should be perpendicular to solid walls, or greater than 75 degrees separation from glass?
ie. if the lighting fixture is inline with a window, than it must meet rule 1 also. is that correct?
this is another credit that a year ago, reviewer passed with photos of recessed lighting and no diagrams, but now, they need calculations for distance of fixtures to glass.
if I prepare theses diagrams for a 14 story building, how many do I need to show? there are LOTS of lighting configurations.
I have not. And reading the text for this is confusing. It does look like plan view but the example they show doesn't make sense to me.
I understand if this was a can light. But they're showing a linear light. As long as the closest point to the window makes an angle greater than 75° it seems to make the whole fixture compliant. But if the fixture was shortened by 2 feet it's all of a sudden non-compliant even though there's less light in the room.
I think this was intended for small fixtures but was shown poorly in the reference guide. Sorry I can't help you.
Always good practice to double check the LEED Interpretations database
This credit had an addenda posted August 1, 2011 (#10000098) with a revised diagram for Rule #3 that clearly labels window and fixture.
Now that I understand the rules better, for existing buildings, it seems the only way to reasonably comply is automatic controls because most typical office buildings have lights in-line with windows that are closer than 150% of window height. And it is unreasonable to re-configure lighting plans for LEED without a larger facility alteration.
Thanks for noticing the addenda, Alyson.
Actually, the revised diagram is still confusing to me. The "line of sight for nearest fixture edge" is not drawn to the nearest fixture edge (it is drawn to the edge closer to the top of the figure, not the "lower" edge which is closer to the window). Also, it seems to me that the way they are notating the angle would indicate that smaller angles would be preferable to larger angles (if the fixture was in line with the edge of the window, the angle would be 90; if the fixture was in line with the center of the window, the angle would be obtuse). Do they mean that the angle should be 75 degrees or GREATER? Or are they showing the angle in the wrong location?
Also, the line that is labeled "perpendicular to wall" is actually parallel to the wall with the window, which I think is the relevant wall. And the reference guide language says to draw the angle "with the vertex located at the window", but the angle drawn in the figure has the vertex and the fixture edge???!???
Maybe I'm missing something (several things, actually) but this seems like a basic geometry question, which I can usually handle just fine. Clarification, please?
From much of the threads in this topic, it appears that the requirement to meet option 2 of this credit is that you "Partially or fully shield all exterior fixtrues 50 watts and over so that they do not directly emit light to the night sky". This has always been my understanding as well.
However, later on in the reference guide (page 70), it states that you have to "Identify all exterior and site lighting fixtures greater than 50 watts and ensure that shields are in place to prevent light from being emitted to the night sky." Would this second statement imply that if you have a 50 watt exterior light, you would NOT have to shield it?
Has anyone submitted (and have achieved the credit) when you have had 50 watt exterior lamps that were not shielded (based on the page 70 description)?
I doubt the Reference Guide can overrule the Credit language.
Agreed, the credit language takes precedence over RG language.
We also have a problem to understand the description respectively to find the right solution. Our building contains exterior lights with 50 watts. In "leed project submittal tips: existing buildings: o&m 2009" you can read "that all fixtures must be adequately shielded if greater than 50 watts".
Have we to change it now or are we allowed to use it?
edited - I knew I should have double checked the wording. A 50W light must be shielded.
Partially or fully shield all exterior fixtures 50 watts and over so that they do not directly emit light to the night sky.
the lights are placed below trees. so it is "partially shieldedIn a partially shielded exterior light fixture, the lower edge of the shield is at or below the centerline of the lamp, to minimize light emitted above the horizontal plane." and it doesn't emit light to the night sky.
does it work in context to the requirements of leed?
LEED doesn't consider trees as 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. for this credit.
ASHRAE/IESNA Standard 90.1-2007 does not specify on LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. Table for Building Exteriors the Flag Pole application. However we need to include it as we have received a LEED review comment to include the Flag Pole light on the exterior LPD calculations. Do you know how can we classify it in order to assign allowable LPD per ASHRAE?
There is no LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. category for flag lighting. You just add it to the project design total. The wattage of a flag light is usually small compared to the project as a whole and shouldn't have much impact on the ASHRAE 90.1 compliance for the site.
For interior lighting, the guide reference indicates that the direct beam illumination intersects solid or opaque surfaces and does not spill to the outside. My question is, the building of the project which I’m working counts with mechanical blinds, and they can be close at night a provide for sure a solid surface, is this possible to document compliance for this credit?.
in the other hand all lights inside the building are partially shieldedIn a partially shielded exterior light fixture, the lower edge of the shield is at or below the centerline of the lamp, to minimize light emitted above the horizontal plane. in order that light is conducted to the task desk but not to the sides. Is this compliant with the credit?
Or what is the best way to document interior light if I do not count whit automatic controllers?
Thanks in advance.
The blinds have to close automatically every night. Explain how they work and their long term reliability being exposed to the elements. If those all work well you should be able to earn the point.
The credit only says they have to be fully shieldedIn a fully shielded exterior light fixture, the lower edge of the shield is at or below the lowest edge of the lamp, such that all light shines down. or reduced light output by 50%. I don't think partially shieldedIn a partially shielded exterior light fixture, the lower edge of the shield is at or below the centerline of the lamp, to minimize light emitted above the horizontal plane. complies.
Without the automatic blinds the best way to document interior lighting is to have the lights on occupany sensors. If the space will be regularly used during night time hours then install two ballasts in each fixture and control with a photocell to keep half of the lighting off at night.
Thank you very much Bill,
Then will be complicated for our building to achieve this credit due the building concept is “passive building-active persons", even when we encourage people to turn off the lights and computers after hours, we have no automatic controls.
What if the ballast were changed for fully shieldedIn a fully shielded exterior light fixture, the lower edge of the shield is at or below the lowest edge of the lamp, such that all light shines down. in interiors, would this comply??
Unfortunately no. The interior lighting doesn't matter if uplight is shielded or not. No direct light from the interior fixtures can go outside of the building envelope. This is really difficult for all types of lighting along the building perimeter.
Has anyone had any experience on how to document this credit for buildings that have parking garage space taking up the first several above-ground floors of a large office tower? The parking garage floors for this building are not open, but completely enclosed in the same glass facade and look as the office floors above. Would these garage floors have to meet the interior lighting requirement and be automatically controlled to shut off after hours, even despite life-safety issues of cars and people navigating the ramps and perimeter space in the dark? Or are garages always considered exterior space and subject to the shielded fixtures/under 50 watts options (which are also not possible in this situation)? The overall exterior perimeter lighting study already conducted does meet the credit requirements. Advice would be greatly appreciated! PS - I assume this decision would likely affect how this interior garage space would be treated relative to other credits such as ASHRAE 62 conformance, green cleaningGreen cleaning is the use of cleaning products and practices that have lower environmental impacts and more positive indoor air quality impacts than conventional products and practices., daylight and views, cleaning audit, etc.
I do not have experience with this situation but I understand the concerns about life-safey issues since stairwells for garages are specifically designed to be highly visible from the street or sidewalk.
Most garage lighting is installed above the low points of the concrete structure so cars or trucks don't clip them. This should prevent most from having a direct line of site to the exterior. You may have to create some sort of shield for the few that are visible outside. To add light to the stairwells and perimeter parking you will need to mount the lights on the exterior wall facing in and/or down. This is the only way I can think of to light the space and prevent the lights from being seen outside of the glass box. Lighting the corners will be tricky. I think it's possible but you'll be having to do a lot of things different. Expect to spend a lot of time proving your design to the reviewer too. Good luck.
Our project site has a foutain/pond that has underwater lights. They are about 500 watts but down't really illuminate the surrounding areas. Do these need to be modified or can they stay since they are underwater?
If you follow option 3 for exterior lighting then your pond lighting should be irrelavant. It does not meet the intent of this credit but option 3 does not measure uplight.
We were following option 2 for everything- so what should we do with the underwater lights? they are only on at night for about 2 hours starting around sunset.
Are you able to change your strategy and comply with Option 3? A 500W flood light cannot comply with Option 2 for this credit. Either rethink if you want/need to uplight this fountain, or if you want/need to earn this Credit.
The only way to get everything you want is to install multiple fixtures around the fountain, each having a wattage of less than 50W. Wattage is based on lamp/ballast combo. The cost of so many fixtures and the burden of relamping them all is not worth the effort.
thanks Bill; can you recommend a device that can be used to measure the illumination around the project boundary? also, what time of night should we aim to take these measurements? (or does it just have to be dark out)
I don't have any preference. Even the cheapo ones did the job. Just do a websearch for "light meter" and you'll get a bunch of results. Prices will range from $100 - $300. Look for one that can measure low light levels of 0.1fc and has a button to lock/hold the display reading. This will push you up to $150 I think.
As long as it's dark it shouldn't matter what time. Maybe start 1 hour after sunset. If it's cloudy you should be able to start even earlier.
The Reference Guide says that measurements need to be taken after "civil twilight" in the evening or before civil twilight in the morning. This U.S. Navy site is the referenced tool for determining civil twilight for your location and date: http://aa.usno.navy.mil/data/docs/RS_OneYear.php.
We have a client with a flag pole and they would like to leave a flag pole light which shines from the ground up to the flag. Is there an exception to the light tresspass or night sky issue? If I stay below 50 watts am I ok?
If you are going to follow Option 2 for exterior lighting then keep the wattage below 50. And for HID, wattage is the combination of lamp and ballast. For incandescent, wattage is the largest rating of the socket.
If that's a proplem then Option 3 is another way. It only measures perimeter light levels.
Does LEED-2009 EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. eliminate any requirements for 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. exterior lighting fixtures at the property line? The only reference I see regarding this issue is listed on Page 72 of the Reference Guide, under "Light Pollution Reduction Strategies." Does this mean that as long as all the exterior light fixtures 50 watts and over are partially shieldedIn a partially shielded exterior light fixture, the lower edge of the shield is at or below the centerline of the lamp, to minimize light emitted above the horizontal plane. so that they do not emit light into the night sky, then this requirement is met?
It sounds like you're combining Option 2 and Option 3. You only need to comply with one of these for exterior lights.
v2 required light levels to be no more than 10% greater at the property line when the lights are on. v2009 increased that to no more than 20% greater. Any 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. requirements for lights near the property line might be a little less strict but nothing specificly has been eliminated. This is Option 3.
I don't have that Reference Guide. If you have a question about the wording could you copy the sentence here.
The parts refering to shielding and lights less than 50 watts is about Option 2. If all light fixtures 50 watts and over are partially shieldedIn a partially shielded exterior light fixture, the lower edge of the shield is at or below the centerline of the lamp, to minimize light emitted above the horizontal plane. so that they do not emit light directly into the night sky, then you comply with Option 2 and can ignore the language in Option 3 about the boundary light levels.
I registered a number of 0.0 footcandle locations, with lights both on and off. Will that be a concern or problem in submitting the data?
Light levels have not increased. Sounds good for submittal.
Our project boundary is one feet thick masonry wall with wall lamps. Kindly share whether the measurement points at the perimeter should be inside the project boundary or outside, to meet the intent of the credit?
You can have the calculation on the outside edge of the wall.
Since the credit is meant to reduce light trespass the wall will be very helpful. You'll probably get the same light level with your site lights on and off.
How tall is the wall? Where are the wall lamps? on top of the wall, inside surface, or outside surface?
Thank you Bill.
The wall is 3m tall and the wall lamps are installed on top of the wall.
You rightly guessed, same light level observed with the site lights on and off.
So would the minimum performance period for this credit be 1 week or is it 90 days?
For credits like light pollution reduction, which are largely about the equipment choices made for a building (shielded fixtures) or equipment setpointsSetpoints are normal operating ranges for building systems and indoor environmental quality. When the building systems are outside of their normal operating range, action is taken by the building operator or automation system. (programming time clocks to turn off lights at night), the expectation is that the equipment and program are in place for the entirety of the three-month performance period.
My project is a resort building where the public areas (lobby ,corridors etc )have automatic control panels to switch off lights after 11 pm.However,the remaining portion i.e. the guest rooms have lighting fixtures that might not be able to comply with the distance or angle exemption rules.
The guest rooms have a key card occupancy control as when there are no guests the room has no power supply.Can the guests rooms be counted under automated control areas?The survey shows that 90% of the guests switch off their lights before 12 PM.
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 from NCv2.2
9/25/2008 - Ruling
 Residential spaces may not be exempted from the interior lighting requirements. ... 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.
Thank you Bill.Another doubt that I have is that my project building is 16 years old.We do not have any lighting plans for the common areas but all are 100% automatic control with fixed lighting schedule.For my submission is it mandatory to provide the lighting layout for areas which fall under automatic lighting control or would it be enough to mention or mark out the zones on a space layout plan?
I have never submitted for a LEED-EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. project so I'm not sure but just from reading the credit it seems you do not need a plan showing interior lighting. Just comment that all interior lights have automatic controls and the total programmed hours of after-hours time is 2,190 hours or less for the year.
Our building is a warehouse with only a single string of clerestory windowsPronounced and sometimes spelled "clear-story," these are vertical, or close-to-vertical, windows high in the wall of a building that bring daylight deeply into the building and, if operable, can help ventilate the space. at the peak of a gabled roof. All interior light fixtures are ceiling hung T-8s that are 10-12 feet below the bottom edge of the clerestory. I cannot determine how to execute this calculation, as the fixtures obviously have no direct line of site from the building. By changing the orientation of some of the calculations, this would work there were skylights, but in fact it a vertical clerestory window in the roof, not in the walls of the building. Could we show photos of the interior and sections of the building with as an alternative compliance method for Interior Lighting? Anyone have experience with this type of alternative compliance method?
For interior lights this credit is looking for a direct line of site to an opening in the building envelope, either wall or ceiling.
What type of ceiling hung T-8 fixtures are these? What does the photometric curve look like? I'm guessing that there's at least some up-light from these lights. If you were at the windows would you be able to see direct light from the T-8 fixtures?
I think a section of the building with light fixture location shown is good for showing compliance. Also attach a copy of the light fixture cutsheet showing what type of fixture this is. Usually the last page of the cutsheet shows the photometric output. If it shows no light coming out of the top of the fixture (between 90 and 180 degrees) then you're good.
If there is direct light going out the windows then automatic controls will need to be shown stating the lights are off 50% of the night hours. At least for the lights within site of the windows.
If this doesn't answer your question let me know.
Our project has exterior lighting that is fully shieldedIn a fully shielded exterior light fixture, the lower edge of the shield is at or below the lowest edge of the lamp, such that all light shines down., however a few streetlamps on the project boundary emit ample light to the night sky. These lamps are on the sidewalk, but technically within our site area. Since they are out of our control, is there any way to reconcile with this credit?
Well, the specifics here can be fairly important. If the lights are 'on' the boundary and owned by the city, they clearly fall outside of your sphere of responsibility. If they are, in fact, within your project boundary, I can imagine two options: the first would be to make the 'control' argument to the GBCI, which I think would be a fairly compelling argument. There's really nothing you can do about city-owned fixtures. Alternately, and perhaps more reliably, you could use the Option 3 approach (with the city-owned lights 'on' in both scenarios) to illustrate that the contribution of the lights you DO control to the nighttime lighting situation is marginal.
Our project is an office space within a warehouse. The only exterior light fixture attached to our property is at the back entrance of our parking garage. Can we still achieve this credit if the scope is so limited? we will be replacing the exterior fixture for one with full cut-off, however, the rest of exterior lights are owned by others.
The main thing I want to respond to is about your whole project, not SSc8. Are you planning to certify just the office space within the warehouse? According to the LEED Minimum Program Requirements for EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems., "LEED projects must include at least one existing commercial, institutional, or high-rise residential building in its entirety."
In principle, I don't know of an obstacle to achieving this credit if it just involves one exterior light fixture. Make sure to address the interior requirements as well.
When finding the difference between light measurements when fixtures are on and off, if the difference is above 20% but the footcandle measurement is below the Maximum Illumination Value for the type of lighting zone does it still comply? For example, if we were in LZ 4 where the maximum is .6 and we got a measurement of .3 with lights off and .4 with lights on (33% difference). Would it be acceptable if one of the requirements is met or does the compliance path have to follow one of the options?
It sounds like it does not comply. The credit states "The illumination
level measured with the lights on must not be more than 20% above the level measured with the lights off."
A couple ideas come to mind. Can you shift the measuring points? It states that you need at least 6 points and no more than 100' apart along the perimeter. Sometimes a 20-50' shift can show surprisingly different results.
If that doesn't work you have a small chance getting this by increasing your accuracy. Does you light meter measure hundredths? If the 0.3 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. value is 0.33 fc with lights off and the 0.4 fc is 0.39 fc with lights on it would be compliant. It's not likely but if you're looking for any ideas it's something to try.
Does the option 2 exemption for exterior lighting apply to fixtures with ratings greater than 50 watts but using lamps 50 watts or less? We have a project with unshielded exterior light fixtures, and our first thought was to make sure each lamp is 50 watts or less as an easy way to satisfy the exterior lighting demands of this credit.
I think your interpretation is consistent with the credit intent - the objective is to reduce illumination to the night sky, and reducing wattage certainly does so. Depending how much you reduce wattages, it may be more or less ultimately effective than 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., but it does meet the requirements.
PE, LEED AP
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