Standards keep getting tighter: a lighting design that was considered very efficient a decade ago won’t earn you any points under this credit today. Even today’s standard practice is not likely to earn you points, so don’t fall in the trap of waiting until the lighting design is complete to calculate the project’s lighting power density. Instead, incorporate lighting power optimization strategies early in design to optimize lighting power density for your project and earn up to five points here.
The best way to earn points in this credit is with a layered approach that provides relatively low-level indirect ambient light supplemented by task lighting. Direct-indirect fixtures just below the ceiling are a good solution, but the ceiling itself has to be highly reflective for that to work. That approach tends to be very cost-effective because you need fewer fixtures for indirect ambient lightingLighting in a space that provides for general wayfinding and visual comfort, in contrast to task lighting, which illuminates a defined area to facilitate specific visual work., and, if done well, it creates a very comfortable and appealing visual environment.
For EAp2, overall lighting power had to be reduced by 10% from ASHRAE 90.1-2007 levels. For EAc1.1, your project earns an additional point for each 5% incremental reduction you achieve, up to a total of five points for a 35% reduction (you can earn a sixth point for exemplary performanceIn LEED, certain credits have established thresholds beyond basic credit achievement. Meeting these thresholds can earn additional points through Innovation in Design (ID) or Innovation in Operations (IO) points. As a general rule of thumb, ID credits for exemplary performance are awarded for doubling the credit requirements and/or achieving the next incremental percentage threshold. However, this rule varies on a case by case basis, so check the credit requirements. through IDc1 for 40% reduction). It helps to set reasonable goals for light levels in the space, on the lower end of IESNA standard recommendations.
This credit addresses lighting power only—not lighting energy use. That means that good practices for reducing lighting energy use, such as occupancy sensors and daylighting with dimming controls, won’t earn you any points here, but they will with EAc1.2: Optimize Energy Performance—Lighting Controls.
There are two ways to calculate lighting power density for your project: the building area method and the space-by-space method. The latter is more complicated, but it tends to work out better if you have a lot of display lighting or decorative lighting. The ASHRAE standard lists allowable lighting power in Section 9.5.1 for building types, and in Section 9.6.1 for individual space uses.
Task lights can be exempt from the calculations if they are furniture-mounted with independent controls (automatic shut-off by timer or occupancy-sensor, see ASHRAE 90.1-2007, 220.127.116.11,p). Plug-in task lights can also be exempt if they are not part of the overall lighting strategy, meaning they are not specified in the design documents. However, if they are exempted from the calculation, they cannot be counted for IEQc6.1: Controllability of Systems—Lighting.
For EAp2: Minimum Energy Performance, you have to hit a target of 10% lower LPD than the ASHRAE 90.1-2007 lighting allowance. For this credit, you can earn points starting at 15% reduction for one point, and in 5% increments up to 35% for 5 points (plus an Exemplary Performance point at 40%, via IDc1).
Lighting power density (LPD) is defined as the total amount of lighting power, in watts, provided to a given floor area, in square feet. A conventional general office lighting design has an LPD around 1.2 W/ft2, while an optimized design can be 0.8 W/ft2 or below.
Lighting power allowance, in watts, is the limit of total wattage for a building or space type allowed by ASHRAE 90.1-2007. It is derived by multiplying the LPD by the gross lighted floor area.
LPD has no direct relationship with how much light the fixtures
provide. Good lighting design focuses on footcandle (fc) levels on the
work surface (30” above finished floor, in the case of an office). A
typical office design has light levels of 30–50 fc. Contrast and
ceiling and wall brightness should also be considered part of good
lighting design as they can have a significant impact on the actual and
perceived light levels in the space.
Define task areas separately from circulation areas to allow spill light to illuminate circulation.
Refer to the ASHRAE tables to figure out your lighting power allowances by building and space type (tables 9.5.1 for building type and 9.6.1 for space type). For each building or space type there is a corresponding LPD in the table. To calculate the lighting power allowance for your project or space type, multiply the LPD by the gross lighted floor area.
In California you can use Title 24 instead of ASHRAE 90.1 as your standard for credit compliance and documentation.
Exempt fixtures include emergency lighting, lighting within dwelling units, and lighting required by health and safety statutes. Certain display lighting is also exempt from the calculations.
Use the building-area method if you want to focus on total project lighting power. In this case, you don’t calculate the lighting power of individual spaces.
The space-by-space method might be better if you have lots of display or decorative lighting. It allows you to take credit for lighting power optimization for each space. In general, the LPD requirements are less stringent than the building area method, and increases to lighting power allowances are allowed for decorative appearance lighting and for highlighting merchandise. However, it’s more work to document the space-by-space method.
Develop a draft layout and identify potential fixtures. Even if the fixtures have not been finalized, develop calculations (see below) for the lighting power allowance and installed lighting power for the project to achieve at least a 15% reduction from the allowance. This provides a realistic target for your lighting designer to work toward.
Do these calculations early in the design stage so that the owner and MEP can get a sense of what overall energy consumption will be and whether this LEED credit is achievable.
Decide which calculation method you’ll use (see below for more). If the choice isn’t clear, run the numbers both ways and see whether the building-area method or the space-by-space method works out better.
Use ASHRAE compliance forms to help with iterative calculations. Compliance forms are available on the ASHRAE website for free download.
This method is easier to document and may be more appropriate if your project includes only a few space types, as it references a single LPD for the whole building.
To determine the lighting power allowance (in watts) for your project building, look up the building type that best represents your project in Table 9.5.1 of ASHRAE 90.1-2007. Multiply the allowable LPD for that building type (in watts/ft2) by the gross lighted floor area of the project. This is your lighting power allowance.
To determine the total installed lighting power (in watts), add up the total watts for all lighting in the project building (omitting exempt fixtures, as noted above). This is your installed lighting power.
To determine the lighting power reduction, divide your installed lighting power by the lighting power allowance.
This method requires that the installed lighting power for each space be calculated individually. The installed lighting power (in watts) of each space type is then compared to the allowable lighting power (in watts) to determine the percentage lighting power reduction.
To determine the space-by-space lighting power allowance for the project:
Determine installed lighting power: Add together the wattage of the fixtures in each of the space types as listed above, except for the increased lighting power allowances for decorative or merchandise display lighting, which will need to be accounted for in a separate calculation. Be sure to exclude exempt fixtures. Sum all the wattage from each space type in the project to obtain installed lighting power.
You can claim an additional 1 watt/sf of lighting power for decorative fixtures in your baseline, but this is only for areas where you actually have decorative fixtures.
It is not realistic to take 1 watt/sf for the entire room where decorative fixtures may be. Only claim the additional wattage around the area where your decorative fixtures are.
Don’t think that you can artificially pad your baseline case with extra watts per/sf for decorative lighting. In the ASHRAE Compliance form and in the LEED Online form, the decorative allowance for your baseline gets reduced to equal the decorative wattage you actually installed. Calculating the additional wattage allowance for your baseline is only to make sure that your have not installed too much decorative lighting.
When two fixtures are provided to supplement each other, you have to assume that both fixtures are on. For example, task lights may be intended to be used when ceiling lights are turned off, but for installed wattage calculation purposes, all lights are assumed to be switched on.
Task lights can be exempt from the calculations if they are furniture-mounted with independent controls (automatic shut-off by timer or occupancy-sensor, see ASHRAE 90.1-2007, 18.104.22.168,p). Plug-in task lights can also be exempt if they are not part of the overall lighting strategy, meaning they are not specified in the design documents. However, if they are exempted from the calculation, they cannot be counted for EQc6.1: Controllability of Systems—Lighting.
If you are developing an energy model for compliance with EAc1.3: Optimize Energy Performance—HVAC, it can help with the lighting system design and to optimize integration with other building systems.
Lighting power can be reduced by designing for indirect lighting with lower ambient light levels and increased task lighting.
Designing for reduced ambient light and more task lighting can also reduce the number of ambient lighting fixtures you need. These tend to be more expensive than task lights, so you might have a lower first cost as a result.
Lamps that are high in power density are halogen and incandescent—avoid these types of fixtures to lower your overall installed lighting power. Instead use high-efficacy lamps such as LEDs, T8 and T5 fluorescents, and compact fluorescents.
In spaces that are used primarily during the daylight hours, early design direction to provide daylight harvesting and to select high-efficacy fixtures can decrease the number of light fixtures. This can lead to significant reductions in installed lighting power, often in the range of 15%–20%.
The lighting designer develops the layout and identifies fixtures so that the design lighting power will be at least 15% lower, on a weighted-average basis, than the ASHRAE standard allows. Use calculation tools (link to documentation toolkit) and ASHRAE compliance forms to run preliminary calculations of lighting density and area.
For potential additional lighting allowances for decorative or display lighting, check ASHRAE Section 9.6.2. This is a function of the type of merchandise and the space area and usually applies only to retail spaces.
Be aware that in ASHRAE 90.1-2007, the lighting power is the maximum wattage of the light fixture and does not include lamp-ballast or lamp-transformer combinations, as was the case with older standards.
Lighting loads can be reduced through by using indirect lighting, lower ambient light levels combined with efficient task lighting, and efficient fixtures such as LED’s, T5 fluorescent lighting, and compact fluorescent lighting.
Reduce energy use with lighting controls such as daylight sensors, occupancy sensors, nighttime setbacks, and dimmers, even though they don’t reduce lighting power and won’t help for this credit.
Ensure that the correct lighting fixtures are specified and that fixtures haven’t been added to the project since the calculations were run.
If concerned about costs, do a payback analysis. Although some efficient fixtures cost more than typical ones, efficient fixtures significantly reduce energy use and operating costs and often have a payback of 1–3 years. Consider this payback analysis before eliminating any installed lighting power reduction strategies from the final construction plan.
Demonstrate compliance with LPD requirements using ASHRAE compliance forms. Upload these forms to LEED Online.
Excerpted from LEED 2009 for Commercial Interiors
To achieve increasing levels of energy conservation beyond the referenced standard to reduce environmental and economic impacts associated with excessive energy use.
Reduce connected lighting power density below that allowed by ANSI/ASHRAE/IESNA Standard 90.1-2007 (with errata but without addenda1) using either the space-by-space method or by applying the whole building lighting power allowance to the entire tenant spaceTenant space is the area within the LEED project boundary. For more information on what can and must be in the LEED project boundary see the Minimum Program Requirements (MPRs) and LEED 2009 MPR Supplemental Guidance. Note: tenant space is the same as project space..
The points earned for reducing lighting power density below the standard are as follows:
Project teams in California may use Title 24-2005, Part 6 in place of ANSI/ASHRAE/IESNA Standard 90.1-2007.
Design the connected lighting power to maximize energy performance. If the project warrants, consider a computer simulation model to assess the performance and identify the most cost-effective energy efficiency measures.
Includes lighting design guidance for many different space types.
Collection of advice from many different sources on optimal daylighting design and fixture selection.
IESNA standard that outlines minimum light levels for various spaces and tasks.
ASHRAE writes standards for the purpose of establishing consensus for: 1) methods of test for use in commerce and 2) performance criteria for use as facilitators with which to guide the industry.
This guide includes instructional graphics and superior lighting design solutions for varying types of buildings and spaces, from private offices to big box retail stores.
Instructions for completing lighting compliance documentation.
Documentation to demonstrate compliance with Standard 90.1-2007.
These sample space-by-space lighting power calculations offers guidance on understanding this calculation methodology.
These sample building-area-method lighting power calculations offers guidance on understanding this calculation methodology.
This sample explanation demonstrates calculations for achieving an additional decorative lighting allowance with the space-by-space method.
The example project documentation shown here includes a narrative describing the lighting system approach and compliance with ASHRAE requirements, ASHRAE forms documenting the allowable lighting power and installed lighting power with supporting tables, a list of fixtures showing installed lighting power, and the interior lighting plan and schedule for the project.
Complete documentation for achievement of EAc1.1 on a LEED-CI 2009 project.
The following links take you to the public, informational versions of the dynamic LEED Online forms for each CI-2009 EA credit. You'll need to fill out the live versions of these forms on LEED
Online for each credit you hope to earn.
Version 4 forms (newest):
Version 3 forms:
These links are posted by LEEDuser with USGBC's permission. USGBC has certain usage restrictions for these forms; for more information, visit LEED Online and click "Sample Forms Download."
Documentation for this credit can be part of a Design Phase submittal.
I received comments back from a reviewer that data center/server rooms should be classified as "active storage" with 0.8 W/sf allowance. We had classified this space as electrical/mechanical with 1.5 W/sf allowance, as there are fine and detailed visual tasks required in these rooms to make fiber optic and CAT 6 connections, perform maintenance, etc. and the lighting needs are certainly higher than that of a storage room. Has anyone dealt with this issue on previous projects and been allowed a higher LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. for these space types?
I'm not sure where to post this EApr2 form but Lighting Power Density question.
I see there has been some discussion about the issue of Title 24 vs. ASHRAE and using a more stringent local energy code as your baseline. I agree that seems to penalize an efficient project.
The form asks for Energy Code used. Since this is a California project, it was designed to Title 24. I was, however, intending to use an ASHRAE baseline. LEED user and reference manual say "may" use Title 24.
So that's my question. Do we "have to" use Title 24 as the baseline because that was the energy code used on the project? Or can we choose to use ASHRAE regardless of the energy code? Here in Seattle, our energy code is more stringent than ASHRAE and yet we are not obliged to use it for the baseline. Do I have a choice?
If you're willing to do the effort of two energy models then you can show compliance to the California Code per Title 24 then again for LEED submittal per ASHRAE.
Thanks for the response, Bill. We're not even doing an energy model. This is just for the lighting power density calculation. By selecting Title 24 as the Energy Code used, our baseline shifts such that I can't use ASHRAE allowed LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. in the space by space calculation but have to use the lower Title 24 allowance.
That means that we will lose lighting power reduction points that less efficient projects will get. And it seems to penalize us for being more efficient to start with.
I was reading thru the EAc1 section of this website and the LEEDuser expert had suggested to people as recently as February of this year to use the system that earns your team the most points. So that was what I suggested to you.
The flip side of this arguement is that in States or countries with stricter energy codes, why should a building be allowed to earn LEED for meeting the Code minimum performance. It might perform better than an average building but then so is every other building in that State. How do you ensure that LEED buildings are exceptional?
Thanks for the clarification, Bill. It sounds like you're suggesting I can choose whether to use ASHRAE or Title 24. That would be a nice outcome if the reviewer agrees.
And I get the argument on local code, but LEED is a national yardstick. Part of the point is to allow you to compare a LEED certified building in Seattle with our climate and building codes with a LEED certified building in Atlanta with their climate and building codes and have an apples to apples comparison. That's why we use the common ASHRAE standard. It's not perfect as it is, but if you go to local code baselines how will this kind of comparison be possible?
My team and I are working on a CI project (office floor) where the tenant has installed occupancy sensors for up to 75% of connected lighting load. In that sense, I would appreciate if someone would tell me if that means that we get the 15% reduction in lighting power as shown in Table G3.2. (Yes, the office floor is less than 5000 ft2) If not, how much reduction in lighting power do we get? and how do we perform such calculation?
In other words, what is the correlation among the amount of sensors that are in place and the percentage of reduction in lighting power?
This is a confusing Table and never made much sense so I've generally ignored it.
I take the Table as only applicable to lighting that does not require automatic shutoff elsewhere in the Standard. If the lights are in a building less than 5,000 sf then you can claim the 15% reduction for adding occupancy sensors. And this is referring to the total building's floor area, not just one tenant. Only claim the savings for the 75% of the lighting load that you have controlled by occ sensor. The number of sensors doesn't matter, just the watts of lighting controlled by those sensors.
(connected lighting load) * (75% controlled by occ sensor) * (15% per Table G3.2) = reduced wattage bonus.
Thank you for your quick reply, Bill. Sorry for the confusing wording. Watts of lighting controlled is what I meant to say by "amount of sensors". So, I see. Given that this is a CI project and the scope of work of the tenant is only within a single floor, then we CAN NOT refer to Table G3.2 to claim any reduction on lighting power by the sensors, right?
Aside from that, I´ve started to document our "Total lighting load for the project space" (Option C) as required by the EA Credit 1.2 form found on LEEDonline and I´m having a bit of a problem determining the "Task lighting that is not exempt per ASHRAE 90.1 2007 Section 22.214.171.124". Could you expand on this, please?
Lastly, I´ve seen the phrase "automatic control device" quite a few times across Section 9 of Standard 90.1. Is this an equivalent term for a sensor/controller when it comes to reducing lighting power? what do they mean by automatic?
There are lots of terms that are confusing until you use it all the time. "Baseline" used to really confuse me, why not just say Code maximum? So yes, "automatic control device" is a sensor, timer, relay panel, or any other non-manual thing that can turn lights on and off. Something other than a simple on/off wall switch. They don't want to rely on people having to remember to turn off the lights when they leave. The phrase has a definition at the beginning of 90.1 that is vauge but says this same thing.
My opinion is that Table G3.2 is only applicable to lights that don't need automatic shutoff. But that's my opinion and I know others disagree. Don't you love Code language?
Section 126.96.36.199 has a list of 16 types of lighting that is exempt and doesn't need to be counted with the total wattage for interior lighting. There have been many projects that would ignore office task lighting because it was being supplied with the office furniture and not by the electrician. Maybe the interior designer hasn't even picked the task lighting yet when the energy model is being done. ASHRAE 90.1 says that ALL interior lighting (excluding those listed in 188.8.131.52) must be counted in the total. This line in the LEEDonline form is a reminder to count the task lighting when you're totaling your interior lighting wattage.
1. I would like to confirm one thing regarding Lighting Power Density Reduction calculations. What is Gross Lighted Floor area that should be used in Building Area Method calculations? In case of office tenant spaceTenant space is the area within the LEED project boundary. For more information on what can and must be in the LEED project boundary see the Minimum Program Requirements (MPRs) and LEED 2009 MPR Supplemental Guidance. Note: tenant space is the same as project space. is Gross Lighted Area equal to gross tenant area (including exterior and interior walls)?
2. I also would like to ask another question regarding different office project. Lighting is not in tenant's scope of work, because it's already good enough and its power is around 20% below lighting power allowance specified by ASHRAE. The tenat won't change anything connected to lighting so he won't e.g. install occupancy sensors to control lighting nor other things mentioned in section 9 of ASHRAE. The question is if the project can still get points under EA Cre 1.1 if lighting wasn't in tenant's scope of work?
1) The Gross Lighted Floor area is measured from the exterior faces of exterior walls or from the centerline of wall separating interior areas. This is per the 90.1 User's Manual.
2) What do you mean the lighting is not in the tenant's scope of work? Is this a new construction CI project are an EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. project? In new construction, all of the lights have to comply with ASHRAE 90.1 requirements. Wall switch sensors are fairly inexpensive to install for small rooms. And adding a couple ceiling sensors to control existing lighting for larger spaces should break a projects budget.
1) Thank you for the clarification.
2) The client will move to a new office space in an existing building. They were not planning to change existing lighting (the lighting fixtures are good enough but there are no occupancy sensors). That's why I wrote that lighting was not in tenant's scope of work.
From what I understand a project has to comply only with these requirements that fall within tenant's scope of work. So if they are not going to change old lighting then they don't have to comply with ASHRAE requirements regarding lighting, is that right?
And if they are not changing lighting fixtures nor adding occupancy sensors (ligthing power density of existing lighting is 15% better than ASHRAE requirements) can they get points under EAc1.1?
There was a similar ruling recently that seems to apply here.
5/9/2011 ID# 10051
I would be careful though. If you are claiming the lighting and controls are existing and outside of your scope of work, then you should not be able to claim the 15% energy savings from the existing lighting. You've just argued it's outside your scope of work. That's just my opinion.
Thank you for your reply.
We have a project with 2 different pendant fixtures that the Owner really wants to use - but they are designed for MR-16 and incandescent lamps.
It appears that, according to ASHRAE 90.1-2007, regardless of the lamp used in a fixture, LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. is calculated using the maximum rated wattage for the fixture.
Is it correct that a fixture designed for use with an MR-16 or incandescent lamp, but utilizing an LED lamp, must still use the MR-16 or incandescent wattage (maximum rated) in energy calculations? If so, is it possible to use a low amp breaker just for those fixtures to limit the available power, thereby lowering the LPD?
You are correct. The wattage is based on the maximum that can be installed in that fixture. Some companies will add at the factory a UL sticker with a lower maximum wattage listed. The fee for this is negligable since it's just a sticker that's changed. But if you can get a company to do this then you can use the new lower maximum wattage.
In our project, we have installed a number of Edison base, screw-in 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. bulb, permanent fixtures. I was under the impression that since screw-in CFLs are, by definition, self-ballasted, that the wattage of the entire luminaire is included in the bulb. I listed the bulbs as self-ballasted in the ASHRAE compliance sheet, but we have received a comment from our reviewer saying that we still haven't included the wattage of the entire luminaire. Is it possible that there is additional ballast in the system despite the fact that we are using self-ballasted bulbs? Or am I missing something else?
Thanks in advance!
Commenting on my own question here, but I figured out the answer. We need to use the maximum rated wattage of the fixture for all screw-in bulbs.
You are correct that you must use the maximum rated wattage when using an Edison screw base with self ballasted 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. lamps, since someone could screw in a standard 60W incandescent A-Lamp. To take better advantage of the real energy use of the CFL, use pin-based lamps. Some pin based CFL lamps use a universal ballast that will operate 26W-32W-42W lamps. To use a 26W lamp only and account for this in LEED, specify that the luminaire be labeled for 26W Maximum.
First of all, I have read previous posts, and I have seen that this subject has already been discussed, but the way I see it, in this case it might be a special circumstance.
We are working on a CI project which spans around 80% of the gross area of the building in which it is located, our clients being the only tenants in the building. The Core and Shell scope of the building is in process of certification. An accessible green roof was installed as part of the core and shell scope, but no lightning or other fittings were delivered for this area. Our CI clients installed all of the fittings for this space, including a canopy, the deck and all of the lightning. Therefore we have included it in the project scope, have been considering it in every credit we expect to achieve, and we will include it in the certification fees when we apply for review.
Furthermore, the credit language speaks about "connected lightning power density" without making regards about interior or exterior aspect of the lightining.
Since this lighting is under the project's scope, we have been including it in our calculations (using Table 9.4.5 to calculate maximum Wattage for this areas). Since the credit template does not makes a provision for this circumstance, we were expecting to mark the special circumstances option.
What do you think about this special case? Any ideas? Do you think we are on the right track?
Thanks in advance for your contribution.
We have a residential project - with a double height entrance lobby (main entrance to the bldg) - and I am not sure how to calculate 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. for this space - should I treat it as:
1) Lobby (14W/m2 = 1.3W/ft2)
2) Hotel Lobby (12W/m2 = 1.1W/ft2) or
3) Atrium - First Three Floors (6W/m2 = 0.6W/ft2)?
My opinion is that the appropriate space type is "Lobby"
I am working on an international project that has novelty lighting and lighting that displays cafe food. Are either of these exempt from EAc1.1? Is there a resource that gives the gist of ASHRAE 90.1 184.108.40.206?
The food display lighting would likely be exempt under ASHRAE 90.1 - 9.6.2b, for merchandise lighting, at 1.0 W/SF. The "novelty" lighting may also be exempt under 9.6.2a, which covers decorative lighting, also at 1.0 W/SF. Both would need to be "automatically controlled, separately from the general lighting, to be turned off during nonbusiness hours."
The ASHRAE User's Manual is a good resource to understand the details of the standard.
I'm working on finalizing documentation for a LEED project. We have completed the calculations and are only looking about 15% savings. However, all the installed ballast are dimmable and all have been set at 70%, is there anyway to account for these savings?
For the LEED CI EAC1.1 - Optimize Lighting Power Density, we have previously submitted documentation showing the connected lighting load in each space, and an additional column applying the fixed dimmed level and resulting reduced power. The important thing to verify is that the 70% dimmed level is actually 70% power. A lighting control company might consider 70% of the 0-10V control signal, a lighting designer may want 70% light output, but for LEED this must be 70% of power. You may need to clarify with the controls manufacturer what the 70% is.
Also, you will need to provide a narrative that confirms that this maximum dimmed level is set in the firmware, or is otherwise a permanent setting that cannot be reprogrammed by the end user.
We have a retail banking project. the building is 2 stories high + a roof top and was renovated. We installed a roof garden on it. we also install light fixture surrounding the roof garden. besides that, the building also has an over hang or canopy with installed new lighting fixtures. all the lighting fixture was connected with our project space control timer and the electricity consume for these lighting is pay by our project tenant. do we need to include the exterior lighting into out LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. calculation?
See comment below
We have a restaurant project (LEED for Retail: CI) in which the tenant has a open space. There is a canopy outside used for retail purposes and obviously some exterior lighting. Should we include the exterior lighting in this credit? If yes, which method should we use?
Thank you in advance.
I don't think you would inlcude exterior lighting. As a CI project I think the assumption is that the project only inlcudes interior space. Are you including this exterior space for other credits? If you are, then I suppose you could just treat it as an interior space. you woudl sue whatever method (space-by-space or building area) that you are using on the interior. Or use the exterior 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 in 90.1-2007 (table 9.4.5). But CI EA 1.1 makes no provison for this in the credit langauge or the submittal template.
You're right. We didn't add exterior lighting into credit calculations, but we showed that it is less than exterior 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. Our credit has been accepted by the review team. I think this is the most convenient way since the project is subscribed as CI.
When reviewing the CI forms from an older project that were filled out by a consultant, I noticed they had taken 10% credit towards the installed lighting power for occupancy sensor control of lighting in rooms such as restrooms, storage rooms, etc. I have not observed anything in ASHRAE 90.7 indicating credit for lighting controls.
Could the consultant have been using Title 24?
Can you obtain credit for installed lighting power under credit EAC1.1?
EAc1.2 addresses controls so, as has been said in other posts, taking credit under EAc1.1 for controls would be double counting.
In any case, for EAc1.1, Lighting Power, the calculation is strictly installed lighting power vs. the allowed lighting power. The 10% power adjustment you mention is from ASHRAE 90.1, Table G3.2 in Appendix G, which provides guidance on creating energy models. Any energy modeling done for LEED-CI would only marginally take this into account, as part of EAc1.3 Optimize Energy, HVAC, where decreased cooling demand would result from the lights being controlled by occupancy sensors not being on, and thus not creating heat.
I hope this helps,
I have a renovation project where there are three rooms in which we are not replacing the light fixtures. ASHRAE 90.1 Section 9.1.1 states, "..lighting requirements for existing building are triggered only when 50% or more of the existing luminaires in a space are replaced. A renovation that replaces less than 50% of the existing luminaires in a space is not required to comply with the standard unless it increases lighting power."
Does this mean I do not have to include these existing fixtures in the interior connected lighting power calculations?
You would excluded a room's lighting power, in which less than 50% of the lighting gets replace. However if you also go for credit EA 1.2 lighting control than you will have to still included it into the total lighting power.
This topic was previously posted under EAp2, but was not getting any responses; this seems like the more relevant location anyways:
I'm encountering difficulty in documenting the minimum 10% lighting reduction. This is due to some uncertainty in the definition of gross floor areaGross floor area (based on ASHRAE definition) is the sum of the floor areas of the spaces within the building, including basements, mezzanine and intermediate‐floored tiers, and penthouses wi th headroom height of 7.5 ft (2.2 meters) or greater. Measurements m ust be taken from the exterior 39 faces of exterior walls OR from the centerline of walls separating buildings, OR (for LEED CI certifying spaces) from the centerline of walls separating spaces. Excludes non‐en closed (or non‐enclosable) roofed‐over areas such as exterior covered walkways, porches, terraces or steps, roof overhangs, and similar features. Excludes air shafts, pipe trenches, and chimneys. Excludes floor area dedicated to the parking and circulation of motor vehicles. ( Note that while excluded features may not be part of the gross floor area, and therefore technically not a part of the LEED project building, they may still be required to be a part of the overall LEED project and subject to MPRs, prerequisites, and credits.), per ASHRAE 90.1-2007. The definition is found here: http://www.gbci.org/main-nav/building-certification/resources/fees/curre...
Per this definition, and from users' experience, does this exclude spaces with a headroom less than 7.5'? What if these areas are part of a larger space that has heights in excess of 7.5'?
Thank you for your help!
the MPR guideline addresses this issue by defining the gross floor areaGross floor area (based on ASHRAE definition) is the sum of the floor areas of the spaces within the building, including basements, mezzanine and intermediate‐floored tiers, and penthouses wi th headroom height of 7.5 ft (2.2 meters) or greater. Measurements m ust be taken from the exterior 39 faces of exterior walls OR from the centerline of walls separating buildings, OR (for LEED CI certifying spaces) from the centerline of walls separating spaces. Excludes non‐en closed (or non‐enclosable) roofed‐over areas such as exterior covered walkways, porches, terraces or steps, roof overhangs, and similar features. Excludes air shafts, pipe trenches, and chimneys. Excludes floor area dedicated to the parking and circulation of motor vehicles. ( Note that while excluded features may not be part of the gross floor area, and therefore technically not a part of the LEED project building, they may still be required to be a part of the overall LEED project and subject to MPRs, prerequisites, and credits.) better. Area with less than 7.5' are excluded. See page 38
Our project is pursuing IEQ C6.1 (Controllability of Systems - Lightings) and therefore task lightings will be provided. Do we need to consider task lightings 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. calculation?
Yes. You will have to include them unless you have a the task lights controlled by motion sensors. It's an exception in ASHREA 90.1 2007
We have received review comments asking us to include the task lighting in the 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. even when we are showing the ASHRAE motion sensor exemption. We are currently trying to rebut the comment. Besides reiterating the ASHRAE exemption, what would you recommend to show you have controllability and can still exclude task lights from the LPD? Thanks
LEED CI 2009 states:
Project teams in California may use Title 24-2005, Part 6 in place of ANSI/ASHRAE/IESNA Standard 90.1-2007.
I searched for recent addenda or updates and there aren't any stating that projects in CA must use a newer version of T24 - like T24, 2010. If I use the 2005, I get a 33% savings as opposed to 13% for 2010. I want to make sure that is okay? Essentially, because CA is really on top of the green thing, if we are required to use the local code based on it being more stringent, therefore, we are pushed into a corner with trying to achieve energy savings. Comments?
Secondly, if we use T24, are we required to complete the ASHRAE Lighting Compliance Interactive forms? Please clarify. Thank you!
Thank you for your question. Since LEED does not set standards, it must refer to other active standards. At the time that LEED CI-2009 was released, the current, active standards wer ASHRAE 90.1-2007, and Title 24-2005. Both of these standards have been updated since LEED CI-2009 was released. ASHRAE 90.1-2010 was released around December 2010, and the current Title 24-2008 was released in January 2010. For more information, please visit:
It is likely that these new standards will be worked into the next version of LEED CI, but they do not apply retroactively to LEED CI-2009. I think that this is for good reason. It would be difficult to impossible for a project that is registered for LEED CI-2009 and had already been designed, documented, and is under construction to suddenly be held to a new standard that did not exist when the project was designed.
Regarding your question on ASHRAE Lighting Compliance Interactive Forms, LEED does not require these forms for their submittal. If you are registered to LEED Online, you should be able to download the LEED Letter Template, which is the form that should be filled out.
Does this help clarify your questions?
All the best,
Hi LEEDUser - First thanks for being an excellent resource. I'm making a general post of some thoughts here because I happen to be looking at this credit for a project, but I think it's a broader issue in how LEED works and how we view green buildings...this idea of "percent better than code".
Dane - while I agree with your logic that we can't expect to move goalposts on projects midstream, I think there's a different issue at hand. The language for EAp2 in CI 2009 seems to penalize projects for better performance by making a more stringent local code the new baseline. So if a progressive state or local agency adopts an energy code that is X% percent better than ASHRAE, a LEED project there will earn fewer points, maybe even fall short of the prereq, even though it is going be more efficient than a building in the jurisdiction next door. If we were using local or regional rating systems, this might make sense, but LEED is national (at least!). This problem seems to be replicated in several areas across LEED and I believe it's being addressed somewhat in LEED 2012.
The bigger picture, though, is that as codes get more stringent, percent-better-than-code becomes less meaningful, especially when that is one of our thresholds for labeling a building "green" or not. Seems like we should focus more on target EUIs....
Just some rambling thoughts - thanks again for all your insights.
I want to make sure that I am clear on the point of the Title 24 standard. Of course we need to follow the latest building code, Title 24-2008. We are planning to follow EAc2 compliance path option 1 "Whole Building Energy Simulation" which references California Title 24-2005 Part 6. I am assuming this is not going to be any issue. Anyone have suggestions or comments?
I assume that when you mention "EAc2...option 1" you actually mean EAp2, in LEED-NC. This forum covers LEED-CI, EAc1.1.
In any case, as your question refers to EAp2, your energy model will be based on Title 24-2005, a less stringent code. So this can only help. Without having studied the expected % efficiency improvement between the Title 24-2005 and 2008 codes, I would assume that additional efficiency improvements would need to be pursued to reach the 10% savings threshold for the prerequisite.
Has anyone had experience in calculating additional reduction 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. by incorporating a significant number of occupancy sensors in their office lighting planning? Is there a way to calculate this additional reduction that is acceptable by USGBC? Alternatively, could using a manufacturer's calculator for proposed reduction utilizing occupancy sensors be acceptable as an Innovation point?
I think I can answer my own question, having taken a closer look at the CI rating system - EAc1.2 addresses controls specifically and any attempt at the above is essentially "double dipping"...
if i were to have timer control on all my ground lighting at my landscape and parking area, do i still need to include these lighting fixtures into my LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. ?
I'm actually not sure if exterior lighting is within the scope of this credit.
But if exterior lighitng IS included, why would having a timer on it make it not relevant? It's still going to use power, right? This seems akin to having an occupancy sensor on an interior light.
Sorry to take so long to get back to you.
Is your question related to LEED for Commercial Interiors EAcredit 1.1 Optimize Energy Performance? If you are working on a Commercial Interiors project, what exterior lighting do you have that relates to this credit?
It seems that your question is related to LEED for New Construction SScredit 8 Light Pollution Reduction, or EAcredit 1 Optimize Energy Performance. For both of these credits, you must include all lighting loads. For EAc1, 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. for all lighting connected to the building's power must be included. If you are using controls that exceed the ASHRAE 90.1 2007 Lighting Controls requirements, these would be accounted for in the Energy Model for EAc1.
I hope this helps. If you can clarify your project and which LEED product you are registered for, I may be able to give you better advice.
we have a 2 stories building with a open carpark + a vegetated roof top. the owner would like to apply for LEED CI, therefore , when we doing 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., we arent sure we need to include the lighting fixture on the open parking and decorative lighting for the vegetated roof into the whole calculation.
though all these exterior light was connected to a timer.
Your project sounds unique for a "Commercial Interiors" project. I believe that LEED CI was conceived for tenant finish spaces and not for building grounds, which would be covered by LEED CS.
For your situation, I suggest that you take the more conservative approach. Under LEED CI, the Lighting Power Density is a credit separate from Lighting Controls. For interior lighting, you must include all connected lighting loads, whether they are controlled by daylight sensors, occupancy sensors, or timer controls. For your exterior lighting, this same approach would apply. You should include all exterior lighting in your calculation. The exterior lighting power allowances in ASHRAE 90.1 2007 are very generous. Too generous in my opinion. Our typical exterior lighting projects are 50% - 80% below the ASHRAE exterior LPDLighting power density (LPD) is the amount of electric lighting, usually measured in watts per square foot, being used to illuminate a given space. allowance, and are still designed to meet IESNA lighting criteria. So, if you include your exterior LPD in the whole calculation, you may find that it improves your % below ASHRAE and may qualify you for more points.
I do not know how a reviewer will interpret this situation, so your Narrative should describe your process thoroughly.
Best of luck,
In an attempt to reconcile user demands- employees over 60 and cultural aversion to be "in the darkness" of 30fc and ASHREA demands we are proposing high power task ights and plug lamps, (Individually controlled with auto shutoff)- point is in some cases task light power is almost as high as general ligting power- does ASHREA or LEED limit 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. that can be exempted as task lighting for any given space ?
Thanks for your question. This topic is a common source of confusion and varying opinions in the lighting industry. Before I get into discussion about lighting criteria and task-ambient lightingLighting in a space that provides for general wayfinding and visual comfort, in contrast to task lighting, which illuminates a defined area to facilitate specific visual work. strategies, I want to stress that your design must first of all address the needs of your client. This often means educating your client, and may even benefit from some demonstration or mock-up. Perception of brightness and visual quality is more complex than can be described solely by task-plane illuminance, so to say employees over 60 have an aversion to "the darkness" of 30 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. is likely an over-simplified opinion.
ASHRAE 90.1 - 2007: 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. for ASHRAE does not include plug-loads. So, officially, plug-in task lights do not need to be included. However, if your lighting design is intented to be a task-ambient system and you are specifying the task lights, it seems to be more in-line with the intent of LEED to include them. There are many very good, low wattage LED and 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. tasklights on the market that will provide plenty of additional light for task specific areas without blowing out your LPD budgets.
Lighting Criteria & the Modern Workplace:
- Traditional Lighting & Criteria: Many clients insist on 50fc avg for their offices. This criteria is based on the IESNA Illuminance Category E, which is based on a task of high contrast and small size. This light level may be appropriate for an employee in their 60's reading black 10-point type on white paper for extended periods of time, or reading blue-line prints.
- Modern Workplace Tasks: Today's workplaces are much more computer task oriented than reading 10-point type or blue-line drawings, so providing 50 fc for the entire office, all day long is not the best use of lighting energy. 30 fc is more than adequate as an ambient base level of illumination for most office tasks today.
The notion of separating task light and ambient light is to provide an appropriate base illumination level for most tasks (30 fc), then provide individually controlled task lights that can provide 50+ fc for a specific task area for tasks that may require higher light levels. By locating the light source closer to the task area, a higher light level can be provided with much less wattage than could be achieved with the overhead ambient lighting system. The 6W LED tasklight at my desk provides 33 fc on its own, with no ambient light. With 30 fc of ambient light, I have 63 fc availble for specific reading tasks. For only 6W additional in an 80 sqft workstation is only .075 W/SF additional power.
The trick to doing a good task-ambient lighting design is to provide task lights that are low-wattage LED or CFL (6W - 18W) with adjustable position to allow each occupant to adapt the task light to their own preference. Another step is to provide a workstation occupancy sensor to turn off the task lights when the workstation is unoccupied. Additionally, coordinating your design with the furniture layout to provide the 30 fc ambient at the Workstations, and less light for (10fc - 15fc) for Circulation Areas, then you can drive your LPD even lower.
If your client still insists on 50 fc everywhere, you may have a difficult time reducing your LPD to meet your LEED goals.
For more on Low Ambient - Task Lighting, refer to:
I hope this helps,
If i were to use Building Area method to do my calculation, what building area types i should used for bank?
The Building Area type that seems to be the best fit for a bank is "Office". However, if I were evaluating a bank, I would probably opt for the Space-by-Space Method that has space types that are more specific to a bank. In fact, I usually use the Space-by-Space Method during the design phases to dial in each of the spaces, then compare the Space-by-Space Method results to the Building Area Method results to choose which one to document for the final submittal.
All the best,
We've got a question concerning "Building Area Method Compliance Path" in the Chapter 9: "Lighting", ASHRAE Standard 90.1-2007.
Appendix G: Performance Rating Method involves the Table G3.2 "Power Adjustment Percentages for Automatic Lighting Controls". In accordance with this Table, in case the total project square > 5.000 ft2
(465 m2) the usage of lamps with occupancy sensor allows to calculate the power at 10% below the nominal value.
Is it possible to make reference to the Table G3.2 (Appendix G) in
calculation of "Lighting" (LEED-CI 2009, Credit EA c 1.1 - Optimize Energy Performance: Lighting Power)?
Thank you for your support!
This is an interesting question. If you were asking about a LEED NC project, then the 10% occupancy sensor savings could be built into the building energy model. However, since you are dealing with a LEED CI project, it is my understanding that Credit EA c1.1 for Lighting Power Density does not allow for reductions due to lighting controls. The occupancy sensors are accounted for in Credit EA c1.2 Optimize Energy Performance - Lighting Controls - Occupancy Sensors for 75% of the Connected Lighting Load. Since there is a separate point for occupancy sensors, taking credit in the Lighting Power Density EA c1.1 would be double counting the points, therefore is not allowed.
We received a comment back on a review of a CI 2.0 project requiring us to use the ASHRAE standard instead of Title 24 (as it states in the 2.0 reference guide). We would be ok under LEED CI 2009 which allows Title 24 to be used for compliance. Has anyone had success using a newer version of a credit to substitute for an outdated version of a credit in an older rating system? Or, does anyone have advice on how to get credit under ASHRAE 90.1 2004 for daylighting controls? Thanks for any and all suggestions!
I do not have any experience with trying to use a newer version of LEED to document a project registered under an older version. However, in both LEED CI 2.0 and LEED CI 2009, Credit 1.1 Optimize Energy Performance, Lighting Power only evaluates the connected lighting load or Lighting Power Density (LDP). Getting credit for Daylighting Controls falls under LEED CI 2.0 & 2009 Credit 1.2 Optimize Energy Performance, Lighting Controls. The requirement for CI 2.0 Credit 1.2 is, “Install daylight responsive controls in all regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building. within 15 feet of windows and under skylights.” In LEED CI 2009, lighting controls are still covered in Credit 1.2, but there are 3 point available. Two possible points for daylight controls and one for occupancy sensor controls.
I hope this helps answer the question.
We have a CI project where they are using daylight responsive controls in some non-regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building. (the central corridors) to reduce lighting loads. That won't count for credit 1.2... do you think we could take the credit for that energy reduction in EAc1.1? Or is this one of those good things to do as a practical matter that doesn't have a tidy fit in a particular LEED credit?
The 2nd point available under EA Credit 1.2 gives credit for "Daylight Controls for 50% of the Lighting Load". This applies to the entire lighting load, including non-regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building.. If you have enough spaces with access to daylight and with daylight controls installed, then you may qualify for this point. Lighting controls do not apply to EA Credit 1.1, which only addresses Lighting Power Density.
Thanks for the help, Dane.
EAp2 requires a 10% reduction in lighting power density. EAc1.1 grants points for 15% or better reduction.
The installation of daylight controls further optimizes the energy efficiency of the lighting design.
This credit requires for lighting controls for 90% of occupants.
Do you know which LEED credits have the most LEED Interpretations and addenda, and which have none? The Missing Manual does. Check here first to see where you need to update yourself, and share the link with your team.
LEEDuser members get it free >
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
Copyright 2013 – BuildingGreen, Inc.