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.

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 emit
light 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.

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.

"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 9.4.1.1 requires automatic lighting shutoff.

---Edit---
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.

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.

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.

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.

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.
https://www.usgbc.org/ShowFile.aspx?DocumentID=9760
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?

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.

OPTION 2
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.

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.

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.

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.

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.

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.

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.

Light levels have not increased. Sounds good for submittal.

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.

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.

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
[3] 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.

Thank You.

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.

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.

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.

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.

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.