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 lightingA luminaire that operates only during emergency conditions and is always off during normal building operation. Emergency lighting is 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.
Sample LEED Online forms for all rating systems and versions are available on the USGBC website.
We are working for G+2 Office Building to get LEED EB Rating. Further, we have completed Ext Lighting and started to work for Interior Lighting requirements. To complete this credit, we need clarifications from your end.
How to determine which are the fixtures are having direct line of sight? and How to draw line of sight.
We are working on a project, whose roof is covered by equipment for most of area. For maintenance purpose, there is 1 tube installed close to the door of roof areaRoof area is the area of the uppermost surface of the building which covers enclosed Gross Floor Area, as measured when projected onto a flat, horizontal surface (i.e. as seen in Roof Plan view). ‘Roofs’, or portions of roofs, covering unenclosed areas (e.g. roofs over porches and open covered parking structures) are not included in the areas used to evaluate compliance with SSc7.2, though they may be applicable to SSc7.1. entrance. Will this can be excluded from calculation of LEED EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating systems. SS9? Actually, we are pursuing SS9 by using v4 although has been registered under v2009.
Lights on the roof should be included in the light pollution calculations. It is still an exterior light and all exterior lights must be compliant. EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating systems. is easier to show compliance with. Just specify a light that is 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. or do the measurements along the property line. I doubt the roof light will affect the property line measurements.
Is the requirement regarding interior lighting applicable also to hotels which are working 24 hours a day?
I looked a couple years ago and never found a single hotel that has earned this credit under V2009. I just searched again on gbig.org and found 10 hotel projects using EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating systems.. Most in India. I don't know what they did to show compliance.
Hotels still need to comply with the interior lighting requirement. It might be easiest if you use the v4 version of this credit since there is no interior lighting requirement.
since your reply is referring to the LEED EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating systems. rating system, can you confirm that it will be accepted to use v4 for this credit? I am asking this because I could not find the credit under the v4 credit substitution list for v2009 projects (published Nov. 2015).
Thank you in advance.
Thanks for checking the list.
I try to verify information before posting. I really started doubting myself. Looks like the rules changed. Using the WayBack Machine it seems the Light Pollution Reduction credit for O&M was allowed to use the v4 version. I never heard any announcement that it was changed.
The first version of this list without Light Pollution Reduction in the O&M was in March of this year. When was your project registered? If it was before March I think you can justify using v4. I'll try to ask USGBC why this changed and if it was intentional.
Thank you, Bill.
Our project was registered in March. We may try and document the credit in reference to the earlier substitution list. Yet further clarification on this issue would be much appreciated. Thank you for your help.
All I've heard so farFloor-area ratio is the density of nonresidential land use, exclusive of parking, measured as the total nonresidential building floor area divided by the total buildable land area available for nonresidential structures. For example, on a site with 10,000 square feet (930 square meters) of buildable land area, an FAR of 1.0 would be 10,000 square feet (930 square meters) of building floor area. On the same site, an FAR of 1.5 would be 15,000 square feet (1395 square meters), an FAR of 2.0 would be 20,000 square feet (1860 square meters), and an FAR of 0.5 would be 5,000 square feet (465 square meters). is that USGBC said it was a mistake that they originally allowed this credit substitution for EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating systems.. They were trying to fix the mistake so they removed it. If I hear anything else I'll share the information.
USGBC will allow projects registered prior to this change to use the v4 credit language. The earliest I can find this change is March 7th, 2016. So a project registered March 6th and earlier can use the v4 credit language. Make sure to note this in the credit form somewhere.
Did you get an official communication from USGBC on being able to use the v4 path for projects registered before March 7th, 2016? We have a submission right now that we've tried to use this path on and are getting push back from the review team. Thanks!
I have nothing official, just an email from a USGBC staff member. I've asked again after your post and have not heard anything.
I get really annoyed with organizations that don't follow their own rules and left hand doesn't know what the right is doing.
I would suggest using the link to show that this was the rule in effect at the time of your registration. This is the website as it appeared and wasn't changed until March 7th, 2016. USGBC rules state that projects must comply with rules as written at the time of their registration. https://web.archive.org/web/20150314002048/http://www.usgbc.org/articles...
I don't know what else I can do to help.
I just got an email from my contact at USGBC.
"In cases such as this, we recommend that projects contact GBCIThe Green Building Certification Institute (GBCI) manages Leadership in Energy and Environmental Design (LEED) building certification and professional accreditation processes. It was established in 2008 with support from the U.S. Green Building Council (USGBC). directly about it for a project-specific answer (whether it be 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, through the website, their account manager, etc). I don't know the project's particular conditions, and I won't be able to make the determination since I'm not on the review side of things. But I encourage them to continue the discussion with their reviewer, and explain the reasoning behind why they would like to use the substitution.
I see the project team's point. I'll ask around again and get back to you!"
Our tenant has a display window with 24/7 illumination. Are there any exceptions for this type of lighting?
ASHRAE allows the exception for the interior power calculation, but I don't know of any exception for display window lighting for this credit. They would need to be turned off an average of 6 hours per night.
Also note that the language of the credit says that all luminaires with a "direct line of sight" to a window must be turned off an average of 6 hours per night. Mount the lights in a way so that there is no direct line of sight to the windows. Can they be hidden above the window, or shielded from view?
Bill, I was aware of the exception for interior power calculations and that is why I wondered about the exceptions for the SSc8 credit. Thanks for your clear answer. The suggestion to point the lights away from the window is an interesting one we will explore.
Are building signs (example; box light sign of property name) included in the exterior lighting requirements?
An internally illuminated sign, no, it is not included in the requirements for this credit. A box light sign sounds like it is internally illuminated.
An externally illuminated sign is. This would be like a flood light on a solid, painted sign.
Is it possible to use tinted window film to reduce interior lighting pollution instead of automated shades? What information would need to be provided to demonstrate compliance if tinted window film is allowable?
This was an option in NC buildings. If you can demonstrate that less than 10% of any light fixture's total lumens are emitted thru the windows.
The easiest way to show this would be to automatically tint the glass at night (50% or more of the time) to limit visible light transmission to 10% or less.
You'd need information from the window film and glass manufacturers to show how much light will be transmitted thru. Also explain the controls that will automatically tint the glass at night.
Thank you for the quick response Bill. I was wondering if you could use tinted window film by itself, without the use of automatic controls. It sounds like the window film would need to be extremely dark (VLT of 10%) in order to comply with the requirements of this credit.
To ensure that the internal lighting was not interfering on nocturnal environment at least 50% of the nighttime hours, the approach that we used was to automate all the building blinds, establishing them to remain closed during the night hours.
Did anyone use this approach? Is it acceptable?
It sounds acceptable to me. Show them a cutsheet of the blind so they can see it blocks light. And a description of the automated controls.
We are working on a multitenant office building, with several vacant spaces. All of the occupied spacesEnclosed space intended for human activities, excluding those spaces that are intended primarily for other purposes, such as storage rooms and equipment rooms, and that are only occupied occasionally and for short periods of time. Occupied spaces are further classified as regularly occupied or nonregularly occupied spaces based on the duration of the occupancy, individual or multioccupant based on the quantity of occupants, and densely or nondensely occupied spaces based on the concentration of occupants in the space. have automatic controls for the interior lighting, but the unoccupied spaces don't. As the spaces are leased and renovated, they are put on automatic controls. Would this prevent us from getting the credit? Or would an explanation of this policy suffice?
If you applied under the Core & Shell this would be no problem. But since it is EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating systems. the whole building needs to comply.
It should not be difficult or expensive to modify the lights in the unoccupied spaces to add an occupancy sensor on all or half of the fixtures. Why are the lights on 24/7 to start with in a space that is unoccupied?
The lights aren't on all the time-in fact, they're off all the time unless a tour is scheduled. That's part of our consideration-we'd be spending money to put occupancy sensors in a space where the lights are kept off at all times and then ripping those lights and possibly the sensors out again when the space is renovated for new tenants.
How are the lights controlled now? A wall switch at the door? For $20-$40 at any hardware store you can find a wall switch sensor. Set the time delay to 30 minutes and when a tour walks in the lights will turn on. And the switch can easily be reused in small restrooms, offices, storage rooms, janitor closet, or elsewhere.
An excellent idea. I'll put it up to the BM and see how everything is controlled. Thank you.
I am looking for some clarification with this credit. I have a copy of LEED Canada for Existing Buildings: Operations and Maintenance 2009, Rating System. It provides 3 options for exterior and site lighting as well, however they are a little different. Option 2 requires you to partially or fully shield all exterior luminaires with 1000 initial lamp lumens or more, and for all exterior lumunaires with more than 3500 initial lamp lumens to meet IESNA's 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. Classification System in RP-33-99.
It is my understanding that the IESNA cutoff classification system was replaced by the BUG Rating system in the IESNA TM-15-07 Luminaire Classification System for Outdoor Luminaires? Please clarify, i'm not sure if I am looking at an older version of the LEED Rating Guide
Yes, IESNA decided to end the 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. classification system when they released the BUG rating system.
But momentum has a power of it's own. The cutoff terms were simple and most people still use the terminology. I'd guess 90% of cities with a lighting ordinance still refer to Cutoff or Full Cutoff light fixtures. What IESNA has done doesn't invalidate all of these laws. Similarly, LEED language is dated but can't be unwritten without the members voting on it.
If the Credit references the Full Cutoff term then comply with it as noted. If you'd prefer to use the BUG rating system then try an alternative compliance path and argue this is newer and more stringent in many ways. But, depending on your lighting zone, the BUG rating system may allow more uplight than complying with full cutoff. It will be up to the Reviewer if they accept this. Hope for the best but plan for the worst.
The first floor of the building that we are working on is 10 feet narrower than the upper floors, in order to accomodate a walkway around a courtyard. The walkway is covered by the overhang from the second floor. We are trying to determine the line of sight for the interior windows on the first floor, but aren't sure how to calculate for this overhang. It definitely affects the line of sight for the fixtures. Any advice would be welcome. Thanks.
I'm not sure I understand the situation. Are these lights on the building interior or exterior?
It sounds like they are outside of the building. If these are exterior lights then the Credit doesn't care about line of sight for interior windows.
They're interior lights and I'm sorry if I'm not explaining this clearly. Two sections of the first floor have a 10-foot overhang, from the windowline out, as the second floor was built out further than the first floor.
We were discussing the distance exemption for the lights in these interior sections of the first floor. At that point, can we use the overhang as the wall opening, as it completely changes the direct line of sight? Or do we still have to use the window opening, even though the light has to travel another 10 feet to escape the overhang of the building?
You can use any permanent structure on your property 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." to block light. If there is an overhang or wall next to the window that blocks the direct line of sight to the light fixture then you can use that. If you have a courtyard that is completely surrounded by your building with a 10' overhand then your interior lights are "shielded". Draw an elevation showing the angles that are blocked from leaving your site.
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 GBCIThe Green Building Certification Institute (GBCI) manages Leadership in Energy and Environmental Design (LEED) building certification and professional accreditation processes. It was established in 2008 with support from the U.S. Green Building Council (USGBC).? No. But I say it meets the intent and is solid as farFloor-area ratio is the density of nonresidential land use, exclusive of parking, measured as the total nonresidential building floor area divided by the total buildable land area available for nonresidential structures. For example, on a site with 10,000 square feet (930 square meters) of buildable land area, an FAR of 1.0 would be 10,000 square feet (930 square meters) of building floor area. On the same site, an FAR of 1.5 would be 15,000 square feet (1395 square meters), an FAR of 2.0 would be 20,000 square feet (1860 square meters), and an FAR of 0.5 would be 5,000 square feet (465 square meters). 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.
I'm thinking that spaces that are used 24/7 may actually ARE exempt from the nighttime lighting control requirements. That's based on this rather cryptic statement in the EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating systems. Reference Guide: "Projects with 24-hour operations are exempt from the requirement for an after-hours override automatic shutoff."
The problem is that there is no such thing as an "override automatic shutoff" in the credit language or Reference Guide--leading me to think that they must have meant to say simply "automatic shutoff." Others I've checked with agree with this interpretation.
Anyone have experience or information that might shed more light on this?
Someone did a poor copy/paste when bringing language in from the New Construction Reference Guide.
The v2009 New Construction Reference Guide uses this language.
"Twenty-four-hour operation projects are exempt from the after-hours override automatic shutoff, and thus must follow Option 2.
All exterior openings, such as windows, must have 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. that can be automatically controlled and programmed to close from 11:00 p.m. to 5:00 a.m. Shielding options include automatic shades that have less than 10% transmittance."
The EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating systems. guide starts by saying, "Control light pollution from interior fixtures with either or both of 2 strategies: eliminateing direct lines of sight, and installing automatic controls"
The language from the NC version had "exempt from" mean "not applicable to". "... and thus must follow Option 2." I'd argue to use the same meaning in the EBOM version even though it is less clear than the NC text.
To rephrase your quote, "Projects with 24-hour operations are not applicable to the requirement for an after-hours override automatic shutoff, and thus must limit direct lines of sight."
But the reviewer is the final word on the matter.
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 184.108.40.206 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??
LEEDuser is produced by BuildingGreen, Inc., with YR&G authoring most of the original content. LEEDuser enjoys ongoing collaboration with USGBC. Read more about our team
The Jewish Reconstructionist Congregation was built with the intent to model...
Copyright 2017 – BuildingGreen, Inc.