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, wasting energy while causing 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.
Full-cutoff luminaires reduce light pollution, improving views of the night sky.
This credit has several requirements, which can make compliance complicated—though not necessarily difficult. One addresses indoor lighting spilling to the outdoors, and others deal with exterior lighting, including façade lighting, site lighting of areas like pathways and parking lots. In most circumstances, these requirements are relatively easy and cost-neutral to meet. The biggest challenge often comes in dealing with light-trespass limits—light bleeding off the project site into a neighboring site—on projects with small or constrained sites. You will also need to attain low lighting power densities per ASHRAE 90.1-2004, which is a good general practice and won’t require you to compromise on aesthetics or cost.
You’ll need to pay careful attention to establishing a LEED project boundary, which plays an important part in meeting light trespass requirements. Involve an exterior lighting designer (or landscape architect) early in the design process to develop photometric plans and guide fixture selection during design.
Yes, as of 4/1/12 per LEED for Homes 2008 Interpretation #10147, “residential spaces (dwelling units only) within the scope of other LEED projects are also exempt from the interior lighting requirements.”
Yes, if they are within the LEED project boundary.
Yes, as long as the entire site meets the requirements.
Significant reductions for tradable surfaces in LZ1 and LZ2 and some in LZ3. See the new table for details.
You can use the curb line.
Use only the area that has measurable light on the surface, baseline and proposed are the same.
At grade level.
No, per ASHRAE table 9.4.5, you can exclude lights in display windows, advertising, and directional signs as long as they are switched separately from other lighting.
If the canopy blocks 100% of the light then yes, but this is unlikely. Any light spillage needs to counted toward the uplighting limit, but calculating this can be difficult.
Not currently, but USGBC is looking at exempting flag lighting from LEED v4 requirements.
Designate one responsible party to oversee exterior lighting-related LEED credit requirements. For large projects, this person may be the civil engineer or landscape architect. For small projects it may be the architect, lighting designer, or other relevant team member.
Identify the building owner’s goals for occupant safety and comfort as well as for architectural lighting, including façade lighting. Include these goals in the Owners Project Requirements for EAp1: Fundamental Commissioning.
One of the biggest barriers to reducing light pollution is the cultural and aesthetic affinity for brightly lit buildings. Owners can play an important leadership role in contending with these expectations, establishing aesthetic goals that do not include excess lighting for purely aesthetic purposes. The design team can play an important role by maintaining low levels of lighting and highlighting specific façade architectural features with focused, low intensity lights.
Projects that demand brightly lit facades and entrances, such as casinos, hotels, theatres and commercial complexes, may have a hard time reconciling these desires with the requirements of this credit. Deliberate lighting design can forge a compromise between the desire to emphasize the building facades and the need to eliminate light pollution in order to meet the credit requirements.
Identify the urban lighting zone as defined by IESNA RP-33, based on the population density of the neighborhood, in order to establish lighting requirements.
Finalize the LEED project boundary in coordination with other LEED credits. The responsible party and the project team should identify the lighting fixtures close to the boundary that will be part of the lighting trespass analysis.
Projects with a zero lot line may choose to use the curb as the LEED boundary for the purposes of documenting light trespass only, while using the site boundary for other credits. This is one of the few exceptions to the rule that the LEED boundary and corresponding site area be consistent across multiple credits. Sites that abut public rights of way may similarly use the curb to establish the site boundary for the purposes of LEED documentation. It can be challenging for projects with zero lot lines or with little open space to meet the maximum exterior illuminance requirement of 0.1 footcandles at the site boundary. Project teams are only responsible for lights that are part of their project. For example, municipal lights about which the project has no control do not need to be considered.
Campus projects can choose whether to comply with the requirements for the building site boundary or to meet the light trespass requirements for the campus as a whole. For a project on a campus, choosing to meet the light trespass requirements at the building level can be very difficult.
Identify local or regional lighting laws or required lighting levels for rights-of-way that may apply to the project site. These regulations may help teams identify areas to focus on when dealing with lighting trespass in the design.
Discuss fixture and lamp options with the landscape designer, civil engineer and other project team members, focusing on both reducing overall lighting power density, and on avoiding light trespass. Avoiding light fixtures that shine up into the sky is the easiest way to reduce light pollution and make better use of lighting. This can be done by eliminating exterior lighting entirely or by selecting “cut-off fixtures” with opaque covers that direct light downward.
Local or regional laws that regulate lighting levels typically do not require minimum input power in watts. Going beyond these local requirements by selecting energy-efficient fixtures can help your project meet codes for comfort and safety goals without compromising energy efficiency.
The credit requires a photometric study on site lighting that may add minor consultant costs but will add value by optimizing the design.
Optimizing lighting can eliminate unnecessary costs for extra lights and high-power fixtures.
Many smaller fixtures may make for a better layout than fewer high-wattage ones. The designer should be able to advise about additional infrastructure costs associated with an atypical lighting design. Low power density and light intensity may require higher first costs for fixtures that will save electricity costs during operations.
Rebates and incentives on the federal, state, and local levels are available for low-power and Energy Star lamps.
Safety concerns are not typically a valid excuse for higher exterior lighting allowances. Despite a perception of better safety with brighter lighting, floodlights can often create areas of deep shadow, and the high contrast can be difficult for the human eye to navigate. Use good design, downlights, and work with the owner to address any concerns.
Be aware of all requirements for interior lights so that fixtures do not direct their maximum candela through windows to the outdoors. Identify locations where fixtures might have a direct line of sight to a window or other opening. The lighting designer should either eliminate those fixtures from the design, provide shades to prevent the maximum candela from shining outdoors, or include controls to turn off all non-emergency lighting after hours.
Interior lighting cannot spill out of the windows after business hours, defined as 11 p.m. – 5 a.m. in the credit requirements. Window coverings or automatic controls like timers, occupancy sensors, or master switches have to shut off or reduce the input power by 50% for all non-emergency indoor lights during that time.
Fixtures that throw 50% or more of the cone of light out a window are likely to present problems.
To avoid letting this credit slip through the cracks, project owners or architects should ask the lighting designers at the outset of the project how they plan to achieve each aspect of the credit.
Additional light controls and automatic window screens may add to construction costs, but controls can reduce electricity consumption.
Identify the project location and IESNA-designated zone to determine the threshold for exterior lighting levels. Utilize resources like the website www.citydata.com to identify relevant population density and appropriate designation.
The lighting designer includes the design intent in Basis of Design for EAp1: Fundamental Commissioning, for all outside lighting requirements, listing minimum illuminance in footcandles, lumens, or candela for all spaces with controls, fixture requirements and design approach.
The lighting designer then develops the exterior lighting layout and selects fixtures that optimize light with low power use.
To determine the total power density for the project, the lighting designer tabulates all exterior space and identifies the wattage of selected fixtures to compare it with the LPD allowable by ASHRAE 90.1-2004, Exterior Lighting Section. The selected fixtures should have full shielding or cutoff to reduce light directed toward the night sky.
The lighting designer develops a photometric study for exterior lighting intensity, the impact of shades and cutoff fixtures, and light trespass from the project boundary. Use the photometric study to inform any changes in the design.
The key to achieving this credit is to find the optimum balance between lighting quality and lighting energy consumption. It is often assumed that more light is better, but a low level of uniform lighting throughout a site will eliminate the need to install bright halogen lamps that illuminate some areas and leave others dark in contrast.
Exterior lighting includes all ground lighting, all façade lighting, flag lighting, any rooftop or terrace lighting, and any other fixtures outside the building. Pay careful attention to exterior light fixtures and light levels at building entrances close to the LEED site boundary.
Revisit the LPD calculations to make sure any design changes maintain the threshold limits.
ASHRAE’s exterior lighting density table (table 9.4.5) lists exterior spaces under two categories. Tradable spaces are those where the average LPD of all those spaces are within the total LPD limits. For example, in parking lots and drives, lighting needs to be a maximum of 0.15 Watts/ ft2. The project may decide to increase driveway lighting to 0.2 W/sf as long as the parking lots compensate with a LPD of 0.1 W/ft2 so that the average of the two is 0.15 W/ft2. For non-tradable surfaces, such as bank ATMs, each space must individually comply with the ASHRAE requirements. Identify whether exterior spaces are tradable in order to provide flexibility.
A photometric study will facilitate communication about lighting levels among the designer, owner and the design team. The study entails computer modeling simulating the lighting intensity of the designed layout in footcandles, lux or candela. It allows the designer to see the resulting output, with iterative design options as the fixtures are reduced or replaced. Typically the photometric study measures light levels in a 10’x10’ grid. The analysis also investigates the maximum initial illuminance value at horizontal and vertical limits on the site boundary to ensure they are within the limits of the project zone. If you find that lights are above the threshold, the designer may want to explore alternative numbers of fixtures and fixture types and present these alternatives to the owner, who makes the final decision.
Avoid aiming light at highly reflective site and ground surfaces, such as white pavement and water features, which can exacerbate light pollution. The photometric study may not capture these characteristics.
Some lighting manufacturers will offer to perform a photometric study of your site if your team selects their product for the project.
Security-oriented lighting designs such as those for prisons, parking lots, and walkways often focus too much on big, bright lamps. This can be counterproductive, creating high contrast between lit and unlit spaces, worsening visibility in both places. Use more moderate, uniform light levels for improved designs.
Some types of lighting are exempt from the ASHRAE limits on power density. Examples include advertisement signage, transportation signage, athletic fields, storage, and historic landmarks and other public monuments. Refer to Exceptions under ASHRAE 90.1 2004 Section 9.4.5.
The lighting intensity of conventional fixtures such as halogens, incandescents, and sodium halide lighting, drops off significantly after the first year of operation. LED or fluorescent fixtures will better maintain their lighting intensity at the level of the installation—contrary to the common perception that low power wattage fixtures, such as LEDs or fluorescents, have low lighting intensities.
Full cutoff fixtures can generally be specified at zero cost premium.
Cost premiums for this credit may come from the higher number of (shorter) poles and fixtures needed to achieve greater lighting uniformity.
New fixtures like LEDs with high lighting levels but low power density may cost more than conventional halogen fixtures, but most of the new fixtures have longer life and are less expensive to operate due to low electricity use and infrequent lamp replacement.
Costs for the photometric study can be decreased if manufactures agree to do their own calculations, which is common if you select their fixtures.
Come to an agreement among the owner, landscape designer and lighting designer about the appropriate lighting levels and site lighting distribution.
Demonstrate to the owner the project team’s decision about lighting levels for the final design. Owners may need to be shown similarly lit areas to understand the implications of a shift from a brightly lit façade and terrace.
Locally mandated lighting levels for exterior fixtures higher than LEED-mandated ASHRAE levels have been a stumbling block for credit compliance, but with proper documentation supported by a clear narrative, this challenge can be overcome. There is an option to not include those fixtures in the LPD calculations and light trespass requirement, but you must demonstrate that these fixtures are full cutoff. To document the credit, make the case that the legally mandated fixtures are beyond the control of the project. Demonstrate that the project has met the requirements with rest of the lighting. Provide a detailed photometric plan, the municipal regulations, and a narrative describing how the project has achieved all requirements of the credit except where the municipal regulations overrule it.
Confirm all the lighting fixtures are listed on the lighting plan. This ensures that the correct components are purchased and installed to maintain the credit requirements.
The designer reviews the final bid documents and budget estimates to confirm that the fixtures have not been substituted for by another type, and that interior lighting controls and window shades are not omitted.
If your team undertakes a value engineering process, make sure the full cutoff fixtures are not eliminated from the list or replaced by incandescent or high-powered halogen fixtures. These changes are often overlooked and may cost the project this credit.
If the project is going for multi-party contractor bid, make sure the bid’s package reflects the fixture specifications and performance. Otherwise the contractor may replace the specification with a similar lower-cost fixture that doesn’t have the same wattage or a cover for cutoff.
Full-cutoff luminaires should not cost more than conventional fixtures, but other common strategies for meeting this credit may add costs. These include controls, timers, sensors, and low-power lights like LEDs. Ensure that these features are not eliminated during value-engineering.
The designer should review shop drawings and visit the site for installation inspection. This ensures that the fixtures have a cut-off for uplighting, the ballasts are as specified, and the controls are all included.
The commissioning agent carries out the functional testing for all control sequences and timers if installed for lighting design.
Timer controls and automatic switches should be commissioned and inspected for performance periodically throughout their life to ensure they continue to serve the intent of the credit requirements.
The facility manager should be involved in the decision of whether to select light timers or automated blinds to comply with interior lighting requirements. Both solutions offer opportunities and challenges during building use, depending on how the building is used and occupied.
Long-life, low-power lamps like fluorescents and LEDs will help keep costs low for operations and maintenance.
Excerpted from LEED for New Construction and Major Renovations Version 2.2
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 on nocturnal environments.
The angle of maximum candelaThe direction in which the luminaire emits the greatest luminous intensity. from each interior luminaire as located in the building shall intersect opaque building interior surfaces and not exit out through the windows.
All non-emergency interior lighting shall be automatically controlled to turn off during non-business hours. Provide manual override capability for after hours use.
Only light areas as required for safety and comfort. Do not exceed 80% of the lighting power densities for exterior areas and 50% for building facades and landscape features as defined in ASHRAE/IESNA Standard 90.1-2004, Exterior Lighting Section, without amendments.
All projects shall be classified under one of the following zones, as defined in IESNA RP-33, and shall follow all of the requirements for that specific zone:
LZ1 — Dark (park and rural settings)
Design exterior lighting so that all site and building mounted luminaires produce a maximum initial illuminance value no greater than 0.01 horizontal and vertical footcandlesVertical footcandles occur on a vertical surface. They can be added together arithmetically when more than 1 source provides light to the same surface. at the site boundary and beyond. Document that 0% of the total initial designed fixture lumens are emitted at an angle of 90 degrees or higher from nadir (straight down).
LZ2 — Low (residential areas)
Design exterior lighting so that all site and building mounted luminaires produce a maximum initial illuminance value no greater than 0.10 horizontal and vertical footcandles at the site boundary and no greater than 0.01 horizontal footcandlesHorizontal footcandles occur on a horizontal surface. They can be added together arithmetically when more than 1 source provides light to the same surface. 10 feet beyond the site boundary. Document that no more than 2% of the total initial designed fixture lumens are emitted at an angle of 90 degrees or higher from nadir (straight down). For site boundaries that abut public rights-of-way, light trespass requirements may be met relative to the curb line instead of the site boundary.
LZ3 — Medium (commercial/Industrial, high-density residential)
Design exterior lighting so that all site and building mounted luminaires produce a maximum initial illuminance value no greater than 0.20 horizontal and vertical footcandles at the site boundary and no greater than 0.01 horizontal footcandles 15 feet beyond the site. Document that no more than 5% of the total initial designed fixture lumens are emitted at an angle of 90 degrees or higher from nadir (straight down). For site boundaries that abut public rights-of-way, light trespass requirements may be met relative to the curb line instead of the site boundary.
LZ4 — High (major city centers, entertainment districts)
Design exterior lighting so that all site and building mounted luminaires produce a maximum initial illuminance value no greater than 0.60 horizontal and vertical footcandles at the site boundary and no greater than 0.01 horizontal footcandles 15 feet beyond the site. Document that no more than 10% of the total initial designed site lumens are emitted at an angle of 90 degrees or higher from nadir (straight down). For site boundaries that abut public rights-of-way, light trespass requirements may be met relative to the curb line instead of the site boundary.
Adopt site lighting criteria to maintain safe light levels while avoiding off-site lighting and night sky pollution. Minimize site lighting where possible and model the site lighting using a computer model. Technologies to reduce light pollution include full cutoff luminaires, low-reflectance surfaces and low-angle spotlights.
This organization provides general exterior lighting design guidance.
Links to manufacturers with IDA-approved fixtures, information sheets and practical guides, and resources for learning.
This website is associated with the Lighting Research Center at Rensselaer Polytechnic.
SUPERLITE 2.0 is a lighting analysis program designed to accurately predict interior illuminance in complex building spaces due to daylight and electric lighting systems.
Lighting simulation software.
For someone who does not design lighting as their primary service, this free lighting calculation software can be downloaded here.
Elights sells full cut-off light fixtures.
A comprehensive source for understanding the lighting models underlying the commercial lighting power limits developed in ASHRAE/IESNA 90.1-2004.
This paper describes a method of measuring and predicting glow, glare and trespass in outdoor lighting.
This publication from the Illuminating Engineering Society defines urban lighting zones according to population density.
This set of annoatated photometric plans was created by Bill Swanson, P.E. for LEEDuser as a teaching tool for SSc8 documentation issues. They are not intended as examples of actual documentation, though a lot can be learned from them. These documents include a detailed plan showing a compliant site with light levels in the site and as required around the boundary, with advice and useful tips. The fixture comparison document is a means to better understand and compare the spill light from different light fixtures and placements. Think of the purple line as the edge of a cutout with a pin thru the paper where the pole is. Move the cutout over the site when locating poles, if the cutout overlaps the line beyond the property line then that fixture cannot be located and aimed as placed. The driveway entrance example shows the impact of fixture placement around driveway entrances, and the special allowance for the site boundary around those entrances.
Perform calculations to demonstrate credit-compliance with exterior lighting power density requirements.
Refer to manufacturer cut sheets for the angle of light spilling above horizontal, the candela graph for maximum candela notation, and watts.
This graphic illustrates SSc8's particular rule for how the site boundary relative to illuminance can expand when a driveway meets a public roadway.
The schedule lists all the exterior fixtures that will be accounted for in the the lighting power density calculations required for this credit.
Provide documentation like this example to showcase the exterior lighting layout plan. You'll refer to this plan in providing fixture and photometric analysis.
Provide documentation like this sample from Asbury Green showing that the angle of maximum candelaThe direction in which the luminaire emits the greatest luminous intensity. does not leave the building interior.
This template is the flattened, public version of the dynamic template for this credit that is used within LEED-Online v2 by registered project teams. This and other public versions of LEED credit templates come from the USGBC website, and are posted on LEEDuser with USGBC's permission. You'll need to fill out the live version of this template on LEED Online to document this credit.
Documentation for this credit can be part of a Design Phase submittal.
What is the minimum requirements of below points for LEED Certification Projects?
U-ValueU-value describes how well a building element conducts heat. It measures the rate of heat transfer through a building element over a given area, under standardized conditions. The greater the U-value, the less efficient the building element is as an insulator. The inverse of (1 divided by) the U-value is the R-value. ?
SHGCSolar heat gain coefficient (SHGC): The fraction of solar gain admitted through a window, expressed as a number between 0 and 1. ?
I don't understand your question. Those 3 values are window properties. They are irrelavant to this credit.
For interior lighting, either automatically turn off the lights during non-business hours, or locate the lights so the brightest output does not shine directly out thru any windows. There are no requiements about the windows.
I am doing energy QA of the project while checking the value of exterior lighting with the SSc8 , it appears that they have taken LEED allowable instead of ASHRAE allowable. Now, i am dividing this LEED allowable value with 0.8(tradable) to get ASHRAE allowable.But the value given by reviewer is not matching with my calculations. can anybody tell me whats is correct calculation to convert LEED allowable to ASHRAE allowable.????
It will be great if provide any example of calc. Thanks in advance.
I apoligize but I may not understand what you are asking.
Why are you trying to convert from LEED allowable to ASHRAE allowable? Most people are converting the numbers the opposite direction. From ASHRAE to LEED. If you are applying for this credit then you need to know the LEED allowable wattage for the site.
For site areas, LEED = 0.8 * ASHRAE
For building facade, LEED = 0.5 * ASHRAE
sir, thanks for your comment.
I've looked at the annotated photometric plan example for this credit, and I noticed that at the project boundary, the vertical and horizontal footcandle values are reported as one single value.
Does this mean we have to combine the two values into one?
I am asking this is because the Lighting designer in our project said her simulation software can only do one simulation at a time, vertically or horizontally, it can not add these two together, as she is using a free software and it has its limitation.
So is it alright to do the vertical and horizontal simulations and report them separately then? If not, can you give me the name of a software that is capable to do a combined simulation please?
Yes, it is fine to report the vertical and horizontal as separate values.
I am also using a free software program. Visual. It has a few grid measurement options. Default, directional, max spill, TV, and LEED 2.1 Trespass. The last one is what I used for the combined horizontal and vertical. It only displays the value which is higher (usually vertical) at each point.
The Visual lighting software program has a free version and a Professional version for $100. If you contact your Lithonia sales rep they should be able to provide you with a free access code for the pro software.
I remember having some difficulty first using the software. A bit of a learning curve. The first 2 weeks are the worst. After a couple thousand hours using it I've become much better.
I have a question about Visual. I'm trying to redo photometric for a skate park where the first photometric shows light trespass, but the person that did it did not take into account a 8 ft solid fence and high landscaping. My question is, can I show this in Visual? I made an 8 ft high "wall" in the program but my numbers were exactly the same. I suppose it's possible that the wall didn't make a difference, I just want to make sure I'm not doing something incorrectly. Thanks in advance!
Is the wall closer to the light or the calc grid? The wall will only stop direct line of sight light. Draw the site in section and make a like between the light and the grid. If the wall is closer to the light pole then it's most likely going over the wall.
We cannot count vegitation as a solid surface. I've never seen a skate park with a solid fence. It's usually just chain link to allow visiblity. That would be difficult to model and not worth the time. If the fence really is solid then draw the solid object. Either a plane or a box with zero reflectance. Make sure the solids are turned "Active" so the calculation counts it. If you draw a plane then check to make sure it's a solid. The default setting always makes them "background" lines that don't affect the calculation.
Is landscape lighting tradable surface?
Landscape lighting is not mentioned in ASHRAE. The wattage for lighting green space is typically subtracted from the Tradable Surfaces allowance. But it is not listed as a tradable surface.
Our building is situated on a college campus, but owned by a different organization. We are designing the lighting according to LZ-3: table 26.4 of IESNA states the lighting for LZ3 is designed for safety, security, and/or convenience. and users are adapted to high light levels.
According to the density surrounding the campus the project would fall into LZ-2. Which is the correct zone to use for this project?
LZ determination is based on density mostly. The desire for safety and security in your design is not a consideration in LZ determination.
Many projects have been pushed into LZ2 by reviewers. If the discription of LZ2 fits your project then that is what you'll have to design to. The desription of LZ3 is anywhere not described by LZ0, LZ1, LZ2, or LZ4.
Reminds me of the contrast between the former Soviet Union & the US...
In FSU, if it isn't permitted, it is forbidden.
In the US if it isn't forbidden, it's permitted.
Posting here even though an EA1 question, since this seems to be where all the outdoor lighting experts are :-)
We are debating whether the Tradeable exterior power allowances are 'use it or lose it' or not. In other words, if I have an exterior walkway that is not lit, can I use that surface area as part of determining my exterior power allowance or does it not get counted. I believe that if it's not lit, the allowance goes away, but others disagree. The User's Manual explicitly says Non-Tradeable budgets are 'use or lose', but it's silent on the Tradeable budgets.
Would love to hear what others' opinions & experiences are.
No responses yet?
Only the Non-Tradable surfaces are 'use it or lose it'.
Tradable surfaces can be counted as a 'savings' if you don't use the full allowance. I see no reason this can't also let you count an unlit walkway into the total site allowance. If nothing directs you to count only illuminated surfaces the way 'building facades' does then we count all surfaces.
I would like to ask about evaluating information light totems or monoliths. Our intention is to place a totem inside LEED project boundary. It will have some logos and texts cut out of the surface and through those holes (covered with semi-transparent material) there will be some LED-light comming out.
How would you evaluate illumination from this instalation for SSc8 credit (v2.2 or v3.0)? How to model it in site area simulation?
I would say it could be considered the same non-tradable surface as building facade 0,2W/sf or maybe better 5W/linear feet (allows us to install more watts).
I am not sure about uplight calculation, but there is enough lumens in a reserve from other lighting fixtures. Any suggestions?
Most people just ignore directional signage relating to this credit. Any internally illuminated sign would be very difficult to measure. Even if it was measured it would have no effect on the boundary calculations. Uplight would have some effect but not likely to be much in comparision to the large site where directional signage is needed. Advertising or directional signage is excempt from ASHRAE 90.1 so you don't need to worry about the W/sf.
We have a huge heavy industry project in Mexico.
Is there a problem if some interior lights of an industrial facility intersect translucent surfaces? even if the light remains inside the project? ie. garden, roads.
The light never leaves the project site or invade public/neighbor domain.
Besides, all the light fixtures are controlled/programed to turn off durning non-business hours.
The credit talks about interior light leaving the building, not site. And only says interior surfaces count as shields. My guess is this is because light doesn't travel thru glass in a straight line and can shatter if many directions depending on the glass type.
You can try to argue it, and you may have a chance if you can convince them the light doesn't leave the site. But don't count on this credit.
We just received comments back on a Design Review. Our exterior lighting complies with the requirements for the credit, but the reviewer raised a number of questions regarding the interior lighting controls.
Our building is a mixed use building with residential occupancy on all but the ground floor. Iinterior lighting in all public and commercial spaces will be controlled per the LEED requirements. However, our reviewer noted that 'we have not shown how lighting controls are installed to power down lights in residential spaces during non-business hours.' This seems odd to me - a residential space is not subject to business hours, and therefore should be exempt.
Could anyone provide some clarification on how the intent of this credit is typically met for residential spaces?
We talked about Residential awhile ago in the NC2009 page on this site. There was no exemption to exclude Residential projects. You'd either have to install auto shades on the windows to close at night, or auto dim the lighting to 50%, or do a complex calculation to show the light leaving the windows is below a certain amount.
Sorry. Seems silly to me too.
Is it possible to comply to the revised requirements in Version 3 even though the project is registered under Version 2.2. The lighting power density requirement for this credit is more stringent in Version 2.2 than in Version 3. Even though we use LEDs on the facade lighting, it is still very difficult to meet the 50% in LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. under this credit in Version 2.2.
Nope. They let projects do this, pick and choose which credit to update, for v2.2 but I've seen nothing that allows it for v2009.
We have two projects where a wall is the project boundary. One is a 12-foot free-standing wall on the owner's property. It shields all neighbors from any site lighting.
Second project...a four-story wall of a neighborboring building is our project boundary. It has no windows.
Do both of these projects comply with trespass rules since site lighting does not and cannot extend beyond the project boundary? The only exterior light on our project is a life/safety fixture over the exit to our building. It is under a canopy but does bounce off the neighboring wall. Any other considerations/calculations other than usual for this credit?
For the first one, other than the typical calculations and photometric site plan, i would recommend some oimages showing the wall. This will give the reviewer a better understanding of the situation.
The second one will definintely need images showing that the neighbors wall does not have any windows or other openings.
I think you'd be fine. I didn't see anything in the Handbook saying the structure had to be owned by the project owner. A solid wall is a solid wall and will shield the light regardless of who owns it.
I plan to get the this credit through simulation.
I heard that DIALUX seems can get it, but I am not so sure.
Please help me and tell me if I plan to get this credit though simuation,
Which softwares can get it and get which part respectively?
Thanks very much
This is a duplicate post that was in NC2009 also. I am not familiar with Dialux but if it can give output values in a grid format then it should work. I personally use Visual software.
One simple question. How do I fill the template when having exempt lighting fixtures in the project? such as for theatrical purposes. Should I make a narrative describing its uses?
If the lighting is exempt just don't included it in the template. In the narrative explain why you excluded that lighting.
I have another question about exempt lighting. If lighting is exempt in accordance with ASHRAE 90.1, then it should be excluded from the LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. calculations for SSc8. But what about the site lumens and light trespass parts of the credit? Can it be excluded for those purposes as well?
I've been trying to reason that it should be excluded from the uplight and spill light also but there is nothing saying offically one way or the other, so that usaully means include it.
It all comes down to what you can convice the Reviewer. The Pilot Credit allows you to exclude it, LEED 2012 allows you to exclude it, We are meeting the intent of the Credit and following the direction of the Credit in it's evolution. But officially, this version, all lighting needs to be counted for light pollution.
I have a redevelopment project in an urban area where the city has requested that the project provide lighting for a neighboring public street and sidewalk. This is being achieved by adding heads to light poles for the parking lot, which face away from the project boundary to light the road. Some bollards are also being added to light the sidewalk. Is this considered a "safety" item and therefore unattainable, or should those heads be eliminated from our photometric plan since they serve a public purpose? Could I adjust the project boundary to include the sidewalk/roadway (although that hurts other credits)? Or go for an alternative compliance approach and explain to the reviewer and see what happens?
Don't expect to earn this credit. Expecially if the lights are on your poles.
I could see the arguement either way. You could ask for a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide or just try submitting with the extra heads eliminated from the photometric plan. Add a note saying that some city requested luminaires intended for city property have been excluded since they are not part of the scope of this project.
We have a building on an edge of campus where the main road entrance turns off an unlight highway. The entry gate has a single pole light that extends beyond the LEED boundary with 0.02 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. roughly 20 feet past our LEED boundary. To me this is a major safety issue to not have the main entrance lit or to offset it enough so that we don't trespass beyond our boundary. Is there any excpetion for a situation like this? COUld it be as simple as writing a narrative explaining the situation because we do not trespass our boundary anywhere else. THANKS.
Sorry, they have always taken the position that safety concerns do not exempt a project from this credit's requirements and that not all projects can earn this credit.
Have you extended the boundary to the curb edge of the road and the drive entrance to the center of the road?
I'm not sure if v2.2 projects can go for pilot credits but if all else fails and you have some spare ID credits not being used then it's worth a shot.
Bill, is there a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide where it says that you can extend the boundary to the middle of the road for an entrance? I have been trying to find one. If not, do you know this technique works from experience or from somewhere else? Do you have to use an alternative compliance path?
I just looked for one also. This may just be a v2009 rule because I couldn't find anything in writing for v2.2
Has anyone been able to confirm whether extending the boundary to the middle of the road is acceptable for NC 2.2 / Schools 2007 projects? Have you used this approach and received approval?
What do you do when the project boundary is at the edge of the existing parking lot but the exterior light fixtures for the parking lot are located within the boundary, on the other side, about 1-2 feet away from the boundary? This is a new science building on campus with no new parking lot provided. The building users will use the existing parking lot adjacent to the new science building. Per LEED, existing light fixtures within the project boundary shall meet the credit requirement by being replaced or retrofitted. Or a campus master lighting plan shall be created to have them replaced according to the credit in the future.
How about maximum allowed light density at the boundary?
Do I still need to meet the 0.10 foot-candle at the site boundary (LZ2-Residentail Area)? How about 0.01 foot-candle 10 feet beyond the site boundary? Those fixtures are needed to illuminate the parking lot, located outside the project boundary.
If these lights are not included in your EAc 1 calculations, not being replaced, not lighting anything within the LEED boundary, and not part of the scope of work for the project, then i would not include them in my submission. A narrative explaining the situation and that it is just one of those circumstances that does occur, especially on a campus project.
You could also move the LEED boundary if it would not effect any other credit and this would completely eliminate the issue.
I have one project which is G+ 3 floor. Ih this there is no exterior light fixtures in the ground floor, but some exterior lights on the roof open parking area.
What i thought there is no need to do lighting simulation to show foot candles at site boundary because all the exterior lights will be on the roof parking area and it does not come to the site boundary . I am doing simulation in Dialux and already have done simulation for 5 projects SSc8 which is accepted by USGBC . If i do simulation on the roof part that foot candle output will show like ground floor and in 3D view will show all lights on the roof parking area.
My question is
1. should required lighting simulation to show the site boundary and 15 feet from the site boundary footcandle values?.
2. If no need to do simulation what is the alternative to explain for site boundary foot candles.
Please help me, it is urgent
I might not understand everything you're asking but I'll do my best. You don't have to show a calc grid on the roof. Just show it on the ground and around the site boundary. It will probably be zero as you suggest but the review team will still want to see something. Just add a note saying that the only exterior lights on the site are on the parking deck at the top of the building. And provide the uplight percentage too. I hope that helps.
Simple question for you all. We have a project that abuts a public right-of-way. In this case, it is a road, but no sidewalk or curb on our side of the street. There is one on the other. Would we consider the curbline as where the street begins on our side of the road or at the curb on the other side of the street?
It would be where the street begins on your side. even though there is no curb. Just use the edge of the road as your LEED boundary.
Our project is a two tower residential and determined as LZ3 zone with GF plaza and 4th floor terrace. If the GF is covered by the 4th floor can we treat the GF as interior space or we have to treat is as exterior?
If the GF plaza is enclosed you can count the space as interior. If it's just covered by an upper floor then it would be considered an exterior canopy.
Follow up question.
If the covered ground floor is an exterior space, any uplight would be considered to the 5% limit as per LZ3 zone; does the covering provided by the terrace level (i.e. 4th flr slab) to the GF can help with the 5% limit requirement of uplight?
All exterior lighting counts towards the uplight limit.
Any perminant hardscapeHardscape consists of the inanimate elements of the building landscaping. Examples include pavement, roadways, stone walls, concrete paths and sidewalks, and concrete, brick, and tile patios. (not vegitation) can be used as sheilds to limit light pollution, either uplight or spill light. So yes, the 4th floor slab can be considered when calculating uplight.
If the 4th floor slab blocks 100% of light above 90° then it's easy math. If it varies based on how far the light is from the edge of the building then you'll need to determine how much light is shielded for each fixture.
We have a building where our main entry on the north side of the building has 4 brick columns holding up a canopy which extends roughly 12 feet from the north face of the building. On the north face of each of these columns is a wall mounted architectural light fixture. So, for these four lights, is the surface area of only the columns considered the facade since those are the only surfaces we are truly lighting or is it the entire north surface area of the building? This may be a simple answer, but it seems odd to me that with 12000 SF of building facade and we light only 120 SF of column surface area that we cannot qualify if the columns are the only areas we can consider as the facade because this building really is minimally lit.
I haven't been able to find any further explanation of what facade area can be counted. I can only go by what the 90.1 standard says, "illuminated wall". If no light from the sconce on the column touches the wall then I would not consider the wall illuminated.
Is your site wattage so tight that 250W will make or break the credit? Did you include the 5% adder? See 9.4.5. The total of the tradable and non-tradable wattage allowance can have 5% added to either category. So, 5,000W of exterior lighting allowance gives you an extra 250W to use anywhere outside. 5,250W total exterior allowance.
If you are still over in your wattage. Now this is a silly situation where adding light may make the site compliant. If you added a few full-cutoff sconces on the wall then you should be able to count all of the wall area below the lights.
Thank you for your quick response. It is close, but that leads me to my next question. Is the 5% adder (for LEED)based on the 5% of the allowable ASHRAE LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. wattages or 5% of the allowable LEED LPD wattages (based on the 20%/50% below ASHRAE numbers).
And, yes, that also was my initial thought that adding on light to a large facade surface area would allow me to comply. Seems kind of contradictory to add light wattage to comply with a credit intended minimize light wattage.
Weird, the pdf on the USGBC website for NCv2.0, 2.1 & 2.2 Rating Systems is no longer available.
I think you meant 80%/50%.
The 5% adder is based on the ASHRAE allowable LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. wattage. Let's see how well I can explain this. Just made up numbers as an example.
You're tradable space allowance is 4,976W and your non-tradable space allowance is 24W then your combined allowance is 5,000W. 5% of this is 250W. You can add this 5% to the non-tradable allowance and have 274W allowable for facade lighting per ASHRAE. Then 50% of this is 137W allowable for facade lighting per SSc8. And 80% of the tradable value is 3,981W for parking lot lighting per SSc8.
- 4,976 watts for parking lot
- 274 watts for facade
- 3,981 watts for parking lot (80% of ASHRAE)
- 137 watts for facade. (50% of ASHRAE)
80%, yes (I was implying the 20% below ASHRAE).
Ok, great. So the 5% comes from ASHRAE 90.1 but indeed the allowed 80%/50% wattages (3981/137 above) are what applies to SSc8. Thanks!
Ok wait, not so great.
My ASHRAE totals are 19684W Tradeable, 1041W Non-tradeable, therefore to maximize my Facade wattages, I can have 15747 Tradeable and 1038 Non-tradeable for LEED, right?. I have 1184W! Is that correct and does this mean I add a light to a large SF Facade surface area to comply? Kind of contradictive.
Your math looks correct.
Can you use a lower wattage lamp in the lights. You only need about 10% reduction in wattage.
You'll need about 2,000 sf of more wall area.
Not to continue to drag the issue along, but maybe someone else will benefit from this. My original question began with the definition of the facade and the limited square footage and the sconces on the face of the columns causing this issue. What about the thought that the columns are for the walkways (tradeable) and not part of the facade (non tradeable). Realisically they are not much different than a pole light out on a walkway. That would make all the math above a moot point.
If you can defend the arguement that this is a walkway light then it would be possible to claim it as part of the tradable spaces wattage.
It's the facade area, which is illuminated by the fixtures, what counts in the calculation. We have been asked to provide photometric plans to show, what can and can not be applied towards the allowance. These were LEED Cs v3 projects and it was only to determine compliance with ASHRAE 90.1 for exterior lighting.
I was just thinking about this tradable vs non-tradable. If you have excess wattage available in the tradable calculation then you can apply it to any surface. It's "tradable".
In Table 9.4.5 where it describes Non-Tradable Surfaces, at the very bottom it states, "The following allowances are in addition to any allowance otherwise permitted in the 'tradable Surfaces' section of this table.)
Sorry for the confusion.
The project is a new airport terminal building zoned LZ3. Due to FAA regulations, the required exterior/site lighting design far exceeds the lighting power densities (LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space.) and site lumen1. A lumen is a unit of luminous flux equal to the light emitted in a unit solid angle by a uniform point source of 1 candle intensity.
2. A measurement of light output. percentages above 90 deg stipulated in the LEED design criteria. In addition, since the LEED project boundary wraps directly around the terminal building apron, light trespass for the terminal building also far exceeds that required of the LZ3 zoning.
Therefore the project team would like to seek the credit via the campus compliance approach. However, this is a large airport property (~3,500 acres) with roadways, terminals, hangars, warehouses, and a myriad of other structure/infrastructure that has been around for a long time.
Do we need to quantify the overall/net LPD and site lumen calculations for the entire campus? Or would a new exterior lighting master plan that incorporates the requirements of SSc8 be sufficient? Do old/non-compliant exterior lighting fixtures on the campus need to changed in order to meet the credit for the one terminal building that we want to certify?
What do we need to do to show that LZ3 light trespass requirements are met along the overall campus boundary and 15 feet beyond? Can a photometric plan be developed for such a big property? Or do we have to conduct field studies to show that campus boundary light trespass levels comply with LEED allowable values?
All inputs appreciated. Thanks so much!
My head hurts trying to think of how difficult this Credit would be to earn at an airport. Do you really need to earn this credit?
A positive note. I think you can argue that specialized lighting directly related to the operation of the airport could reasonablly be excluded from the exterior lighting requirements. I've also heard of helipad lighting getting an exception.
Per Pilot Credit 7 "Excluded: - lighting for industrial production, material handling, transportation sites, and associated storage areas;"
Now, security lighting cannot be excluded so no extra lights at gates or fencelines. Roads entering will need some sort of dark gap between the road and the drive into the airport.
Meeting the interior light requirements will be easier than v2009 but all of the airports I've been in love throwing light around the interior. Expecially by the ticket counters. You'll have to verify the peak angle of light output hits a solid wall/ceiling/floor, for every light.
I've seen projects earn this point using the campus method and submitting a master lighting plan to eventually bring the entire site with compliance.
If you try this and they accept this master plan strategy then you would only need show the LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. on the area your project covers.
Can a photometric plan be created? Yes,
Can it be printed in a functional way to show grid points 10' apart on a site that is 3,500 acres? I wouldn't want to try. You could export the calculation as a dwg file and try to upload that monsterously large file as the submittal data.
I hope some of this helps. Good luck.
I think interior lighting is OK, just exterior that is a little more complicated.
You said you've seen projects earn this point by submitting a campus master lighting plan to eventually bring the entire site with compliance with SSc8 requirements. So that means every future LEED-certified building on the campus has to meet the master plan. However, does this exclude this particular terminal building from not meeting those requirements? I mentioned that the project-specific LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. and site lumen1. A lumen is a unit of luminous flux equal to the light emitted in a unit solid angle by a uniform point source of 1 candle intensity.
2. A measurement of light output. characteristics does not meet SSc8. If this is unacceptable, does that mean that this and future similar projects on the airport campus will not be able to achieve SSc8?
For light trespass beyond the boundary of the airport campus, perhaps some field measurements at selected perimeter of the the overall airport might suffice?
The campus master plan example I mentioned was from the Harvard documents posted on their green campus website. It means all future work has to comply. Not just LEED work. If you want the campus compliance method then the whole campus would need to eventually comply with the credit's requirements.
If they accept the master plan strategy then the current project gets a break on the spill light requirements because the boundary has been moved back to the property line rather than the project line. Should be farther away and pretty simple to show it meets the spill light limits.
It does not exclude your current project from the uplight or LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. limits. These still are required. So max of 5% uplight and 80% of ASHRAE wattage.
You can try to apply the exceptions from Pilot Credit 7 to exclude some lights from the uplight calculation.
I doubt they had any intention of regulating airport sites when ASHRAE wrote their standard. In ASHRAE 90.1-2004, 9.4.5, there are various lights that may be excluded from the exterior LPD. A lot of these exceptions will help your airport project. Lights related to transportation sites are excluded. You may be suprised at how low your LPD goes when whole categories of lights are removed from you calculation.
Thanks Bill. This is helpful.
Do Pilot Credits apply for LEED-NC v2.2 projects?
No. But the NC v2.2 credit mentions that "all site and building mounted luminaires" must meet up-light and spill light limits by zone. I think it's fair to argue that transportation related lighting is not the same as "site" lighting. And that you relied on more current information in PC7 to better understand what types of lighting is site lighting and what is considered for other purposes, like transportation or directional marking. Also that these lights were excluded from the LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. so you didn't see them as applicable to include in any up-light calculation. You're just being consistant and making every effort to meet the intent of this Credit.
The definition of the Project Boundary in the LEED for Schools 2007 edition is rather vague and not really clear. From looking around here at different topics it seems as though the project boundary is considered to be the property line of the project. Is this correct?
We have a school that is part new, part existing and work was done outside the property line to improve bus access to the school.
Most people generally have defined the boundary as the property line. But you were allowed to pick your own project boundary as long as you're consistant between all of the credits.
I would like to clarify about exterior site boundary point-by-point calculation. How to do the photomatric site plan should include point-by-point illuminance level calculations across the site (on a 10-foot by 10-foot grid) that extend 15 feet beyond the property line and /or site boundarylines for this LZ-3 site. I got comments from USGBC for one of my project.can anyone help me.
PE, LEED AP
Smaller parking lots can mean less exterior lighting to design for SSc8 compliance. (Although parking lots can be adequately lit while complying with SSc8).
Low lighting power density for exterior lights, and interior light controls assist in reducing energy cost as compared to an ASHRAE 90.1-2007 baseline. All mandatory requirements are to be complied with for all exterior lights.
Design lighting controls and shading devices so that they also perform during the day for lighting controllability, daylighting, and views.
Design lighting controls and shading devices so that they also support daylighting and associated energy savings.
Design shading devices that don’t interfere with daytime views.
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