-
Use a collaborative design process
Access to daylight inside buildings makes for healthier and more comfortable occupants—and is also linked with greater productivity. When designed with proper glare control and minimized solar heat gain, daylighting provides high-quality light while significantly reducing energy use for lighting and for cooling. Increased daylight through increased vision glazing can help projects earn EQc8.2 for access to views. Realizing the benefits of daylighting requires a collaborative design process.
Balance other design goals
Keep in mind that daylighting strategies must balance with other design goals. For example, you will want to provide enough glazing area for daylighting, plan for open spaces that allow for light transfer, but not at the expense of too much heat gain, glare, or loss of privacy. Incorporating daylighting goals into the early planning stages will help project teams avoid design conflicts at more advanced stages. Daylighting goals should be laid out explicitly in the Owners Project Requirements document required for EAp1: Fundamental Commissioning.
Documentation can be cumbersome
This credit is can be easier to achieve for projects with large windows, open floor plates, and with most occupied areas near the perimeter. However, the documentation may be cumbersome and time consuming for some large projects, depending on the chosen compliance path.
Legend
- Best Practices
- Gotcha
- Action Steps
- Cost Tip
USGBC
Excerpted from LEED for New Construction and Major Renovations Version 2.2
EQ Credit 8.1: Daylight and views - daylight 75% of spaces
1 Point
Intent
Provide for the building occupants a connection between indoor spaces and the outdoors through the introduction of daylight and views into the regularly occupied areas of the building.
Requirements
Option 1 — Calculation
Achieve a minimum glazing factorThe ratio of interior illuminance at a given point on a given plane (usually the work plane) to the exterior illuminance under known overcast sky conditions. LEED uses a simplified approach for its credit compliance calculations. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis) and window height. of 2% in a minimum of 75% of all regularly occupied areas. The glazing factor is calculated as follows:
[INSERT FIGURE HERE]OR
Option 2 — Simulation
Demonstrate, through computer simulation, that a minimum daylight illumination level of 25 footcandles has been achieved in a minimum of 75% of all regularly occupied areas. Modeling must demonstrate 25 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. under clear sky conditions, at noon, on the equinox, at 30 inches above the floor.
OR
Option 3 — Measurement
Demonstrate, through records of indoor light measurements, that a minimum daylight illumination level of 25 footcandles has been achieved in at least 75% of all regularly occupied areas. Measurements must be taken on a 10-foot grid for all occupied spacesOccupied Spaces are defined as enclosed spaces that can accommodate human activities. Occupied spaces are further classified as regularly occupied or non-regularly occupied spaces based on the duration of the occupancy, individual or multi-occupant based on the quantity of occupants, and densely or non-densely occupied spaces based upon the concentration of occupants in the space. and must be recorded on building floor plans.
In all cases, only the square footage associated with the portions of rooms or spaces meeting the minimum illumination requirements can be applied towards the 75% of total area calculation required to qualify for this credit.
In all cases, provide daylight redirection and/or glare control devices to avoid high-contrast situations that could impede visual tasks. Exceptions for areas where tasks would be hindered by the use of daylight will be considered on their merits.
Potential Technologies & Strategies
Design the building to maximize interior daylighting. Strategies to consider include building orientation, shallow floor plates, increased building perimeter, exterior and interior permanent shading devices, high performance glazing and automatic photocell-based controls. Predict daylight factors via manual calculations or model day- lighting strategies with a physical or computer model to assess footcandle levels and daylight factors achieved.
Technical Guides
Window 5.2 computer program—The Lawrence Berkeley National Laboratory
This is a database of window brands, VLT and U-values for different glazing manufacturers. The program provides a versatile heat transfer analysis method.
Whole Building Design Guide—Guidance for Daylight Design
This is an excellent resource for researching how to apply different daylight strategies and the implications the design strategies may have. Includes information on materials and methods of construction as well as calculation tools and software resources.
IEQ Space Matrix
This spreadsheet categories dozens of specific space types according to how they should be applied under various IEQ credits. This document is essential if you have questions about how various unique space types should be treated.
Software Tools
Building Lighting System Software Tools Directory
This is a comprehensive list of modeling tools compiled by the U.S. Department of Energy.
Radiance—Lighting Design Software
This daylight modeling tool is widely accepted in the lighting industry.
Virtual Environment Apache Thermal Analysis Software
A simple modeling tool for preliminary light and energy analysis. Virtual Environment software, or VE-Ware, gives you instant feedback on a building's energy consumption and carbon emissions, as well as benchmarking it against the Architecture 2030 Challenge if it is located in the US. You can access the carbon and energy calculator through the Revit and SketchUp plug-ins.
AGi32—Lighting Design Software
This is one of the most frequently used daylight modeling computer simulation programs. AGi32 offers lighting analysis software for calculations and renderings of electric lighting and daylighting systems.
SketchUp
SketchUp is used to create 3-D graphic models that can help in your daylighting analysis and documentation.
Organizations
Heschong-Mahone Group
This is a lighting group that has published research on the effects of daylighting.
IES—Illumination Engineering Society of North America
This is the organization that sets lighting standards. The IES also works directly with ASHRAE to develop energy standards.
Publications
Daylighting in Schools: Reanalysis Report
This is a case study for the effects of daylighting on productivity in schools. Prepared by Heschong Mahone Group for the California Energy Commission.
Psychosocial Value of Space—Whole Building Design Guide
This is a study exploring the relationship of daylighting and other design features on human psychological well being. By Judith Heerwagen -
J.H. Heerwagen & Associates, Inc.
Windows and Classrooms: A Study of Student Performance and the Indoor Environment
This is a case study for the effects of daylighting on productivity in schools. Prepared by Heschong Mahone Group.
LEED Online Sample Template – EQc8.1
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.
LEED Online Supporting Calculator – EQc8
This "Glazing FactorThe ratio of interior illuminance at a given point on a given plane (usually the work plane) to the exterior illuminance under known overcast sky conditions. LEED uses a simplified approach for its credit compliance calculations. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis) and window height. and Access to Views Calculator" can be used in support of EQc8.1 and EQc8.2 documentation. This calculator is a flattened, public version of a dynamic template for EQc8 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.
Design Submittal
Documentation for this credit can be part of a Design Phase submittal.
LEEDuser is produced by BuildingGreen, Inc., with YR&G authoring most of the original content. LEEDuser enjoys ongoing collaboration with USGBC.
140 Comments
Question about total area that qualifies for LEED IEQ 8.1
Hi everyone,
I am running two simulation at 9am and 3pm September 21 to determine the total qualified area percentage that apply for the credit or not. (Total regularly occupied space: 12170 ft²)
The results I have obtained from the 2 simulations are as follow:
- 9 am : 73.38% (8,930 ft²)of the area qualifies between 10fc and 500 fc
- 3 pm: 77.35% (9,413 ft²) of the area qualifies between 10fc and 500 fc.
Knowing that the daylighting zone percentage of 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. is given by the division of the total daylighted regularly occupied area by the total regularly occupied area, what is the final answer ?
Should both time simulation (9am and 3pm) be over 75% or does it work to make the average of the two; (73.38%+77.35%)/2=75.36 % ?
Thank you very much.
Best.
You cannot average the results of both times to get the compliant percentage. It will be your worst case scenario which will be the 73.38%.
The language clearly states 75% at both 9am and 3pm.
You may want to look at what spaces you have in the simulations and you may be including spaces that would not be considered regularly occupied or could be excluded. Also, double check your gross regularly occupied square footage.
Hi Todd,
Thank you for your expertise. Speaking of the gross square footageSum of the floor areas of the spaces within the building including basements, mezzanine and intermediate-floored tiers, and penthouses with headroom height of 7.5 ft or greater. It is measured from the exterior faces of exterior walls or from the centerline of walls separating buildings, but excluding covered walkways, open roofed-over areas, porches and similar spaces, pipe trenches, exterior terraces or steps, chimneys, roof overhangs, and similar features., it is not at the project advantage to include wall/shaft areas when defining the boundary areas.
Is it permitted to only calculate the Net usable space area ? (I would like eventually to increase the 73.38 to 75 using this method)
Thank you,
Best.
Oliver,
What i should have noted was to check your gross regularly occupied space instead of the gross area. Look at things like corridors and areas which would be considered circulation. Those areas would not be considered regularly occupied.
You are correct in that it only usable space can be considered. So wall shaft areas should not be included.
Some other items that you may want to look at is surrounding existing structures and other features. If you are not meeting compliance based on areas exceeding 500fc which is typically due to direct solar penetration. Surrounding buildings and other features would provide the shading needed to reduce the levels below the 500fc.
Other items would be your input parameters. Are your surfaces orientated the correct way? What about internal reflectances? Depending on the program, if your surfaces are not correctly orientated, then this would cause the amount of sunlight entering the space to be zero. If using a Radiance based engine, what are your bounces set at?
Using Simulation results for EAp2 and EAc1 but not using it for
We are working on a new terminal building for an airport n a remote location. The weather is tropical humid climate so we had to include as many louvers and elements as possible to reduce heat gain and maintain comfort. However, we are getting bad results in the simulation for daylighting. Can we use the simulation results for Energy and Atmosphere but then disregard these results for daylight and do the calculation in the LEED calc sheets?, this is getting better results for daylight than the simulation. Is this possible?
You can use daylight sim results to help document your EA credits and then use the glazing factorThe ratio of interior illuminance at a given point on a given plane (usually the work plane) to the exterior illuminance under known overcast sky conditions. LEED uses a simplified approach for its credit compliance calculations. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis) and window height. calculations in EQc8.1.
Thanks Todd. The building is also an un-sealed building, we do not have glazing in most areas, just a screen, in this case, can the calculation still be done?
Technically you could still use the glazing factorThe ratio of interior illuminance at a given point on a given plane (usually the work plane) to the exterior illuminance under known overcast sky conditions. LEED uses a simplified approach for its credit compliance calculations. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis) and window height. calculations. This is how i would do this to ensure the reviewer does not question the applicability of the glazing factor method with all those lourvers.
I would use a VLT of 92% or maybe even 90%, given that typical screen has a very large openess factor. The area of the glazing would be open area between the lourvers that has direct view. So lets say the lourvers are at a 30 degrees below nadir. The distance used would be the measurement from the exterior edge of one lourver to the interior edge of the lourver above or below that one. I would not perform this without consideration of the louvers if they are angled. If perpendicular from the glazing you could perform this without considering them.
I'd really have to see what your facade looks like to give you my best suggestion.
I wouldn't bank on getting this credit with the glazing factorThe ratio of interior illuminance at a given point on a given plane (usually the work plane) to the exterior illuminance under known overcast sky conditions. LEED uses a simplified approach for its credit compliance calculations. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis) and window height. calculations. There really isn't a window type that applies to multiple louvers. I'm not going to say that it's not possible though. There are just no guarantees when it comes to cases that are outside of the book case.
I think it's possible that you could be rejected for this case due to the lack of glazing as well. I say this because if is considered an exterior space, then it cannot be considered as regularly occupied space. Do you have any mechanical heating or cooling in these areas? If you do not, it might be considered exterior space.
I have never tried submitting a case like this. Please come back to the forum later to report how it goes.
I'm curious, how "bad" are the simulations?
Hi Todd, Jill
Since we are not able to use the simulation results for daylighting which are not showing actual daylight levels we have inside the building, we are going to go for option 3, documenting and measuring actual daylight levels inside the building using a 10f x 10f grid. It says on the checklist here we should do 4 measurements on each point on the grid, so in this case I will assume the 4 measurements have to be taken in a time frame within the hours or operation of the building. The airport operating hours will be from 7am to 2pm only, since at that time operations are closed and the airport is closed. In this case I would do 4 measurements at 7am, 9am, 11am, 1pm. Is this what 4 measurements refer to?
Todd, I cannot find a way to upload the image of the airport but you can access the project's website and you can see the projects elevations and images there. Hope this helps in you providing further suggestions and comments that could help us best document this credit.
http://www.ecogal.com.ec/
Veronica, you do not need to take four different measurements at four different times. One measure at each point in the determined grid as close to noon as possible under clear sky conditions. I would use a 10'x10' gird for spaces that are more than 200 sq ft. Any space smaller than that i would used a 5'x 5' grid.
A very nice project by the way.Looking at the images and plans, and based on its location, i can see why maybe the simulations are not showing credit compliance. Noon at the equator, the sun is directly above you, and with all the overhangs i can see how it may not be getting the 25 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., but without any glazing I'm still not sure why. How is the daylight otherwise.
In reading the the brochure, which a person in the office translated, it states that the project is the first ecological airport in the world with certification. Can you expand on what certification that may be? Thanks.
Hello Veronica, I am curious what checklist you are looking at? There is nothing in the credit that mentions 4 measurements. There is also nothing that specifies time or date for measurement in this version of LEED for this method, so you may want to do a sampling at different times and dates to see what works best for you. I'm sorry, but the link to the project isn't working for me right now.
Also, please note that the minimum required footcandles was changed in an Addendum in Nov. '09 from 25fc to 10fc. So that should help some!
Using a 5' x 5' spacing in smaller spaces is recommended but not required. In the simulation option you cannot use less than 9 measuring points per room no matter what the spacing, so that is probably a good guideline too.
I also want to remind you that you have the option to combine methods, so if any of the spaces complies with simulation, you can submit the simulation for that space, submit the prescriptive method for spaces that comply that way and then use measurement for the rest of the spaces. Not sure if that makes it easier on you or not.
Jill, this is a 2.2 project, so the addenda changing the values to 10fc is only applicable to 2009 projects.
Hi Tood, Jill,
thanks again for the comments, these are helpful. The four measurements we specified ourselves for the measurement and verification plan as a mean to verify if the daylighting sensorsA lighting feature that takes advantage of sunlight to cut the amount of electric lighting used in a building by varying output of the lighting system in response to variations in available daylight. They are sometimes referred to as "natural lighting control sensors " or "photocells." are correctly calibrated and giving the energy savings expected.
The project is aiming for LEEd Gold, even though given the project's location and constraints have un looking at LEED silver, but this is the certification the brochure refers to, meaning that this is the first airport applying for a LEED certification, according to the developers, but I am not certain that this is the first one.
We are performing the lighting measurements this week, so I will let you know what results come up.
And one last question to both of you, so 75% of the spaces does this mean literally 75% of all spaces including restrooms? so for example 75 of 100 spaces regardless of the area?, or does it mean 75% of the area of the building? I have had conflicting views from others in our team.
Thanks for your help!
No, it means 75% of 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. (ROS). I capitalize because this is a LEED defined term. Restrooms are not ROS. The definition of this term has changed around a lot and I'm not sure which one now applies to LEED 2.2. For LEED 2009, there is a "Space type matrix" you can find here. http://new.usgbc.org/resources/eq-space-type-matrix.
For 2.2 it used to be based on "where workers stand or sit" to perform their duties and wasn't based on the amount of time spent in the space as "regularly occupied" seems to imply. For 2009, they list one hour as the minimum time before considering a space ROS. In general, I would say that storage rooms, restrooms, utility rooms and the like are not ROS.
If you have questionable spaces, you can post those here to get an opinion.
Daylight Factor Calculation (includes direct sunlight or not)
I am calculating the daylight factorThe ratio of exterior illumination to interior illumination, expressed as a percentage. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis), and window height. using a lighting simulation in Radiance for Ecotect. I usually run the simulation for overcast sky conditions becaouse I don't want to include direct sunlight. My question is weather LEED requirements for a minimum Daylight factor of 2% in
75% of all spaces, includes direct sunlight or not. Thank You
Please note that daylight factorThe ratio of exterior illumination to interior illumination, expressed as a percentage. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis), and window height. and glazing factorThe ratio of interior illuminance at a given point on a given plane (usually the work plane) to the exterior illuminance under known overcast sky conditions. LEED uses a simplified approach for its credit compliance calculations. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis) and window height. (the one in this version of LEED) are two different things. Glazing factor assumes an overcast sky and does not require simulation. Correct me if I'm wrong but isn't there a spreadsheet calculator that is provided by LEED to enter in all of the glazing factor information and then it calculates it for you? (I'm having an issue with getting into my account right now, or I'd go look myself.) So, I think doing a separate calculation in Radiance for Ecotect is unnecessary for the Option 1 - Glazing Factor. If you are using Radiance for Ecotect for Option 2-Simulation, then you need to use sunny skies.
I am using Radiance to calculate Luminance levels for Option 2. On the LEED® Credit EQ-8.1 I read "Achieve a minimum Daylight FactorThe ratio of exterior illumination to interior illumination, expressed as a percentage. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis), and window height. of 2%(excluding all direct sunlight penetration) in 75% to achieve effective daylighting." so I was wondering weather the simulation counts for sunny skies. Also, the project is in California so most of the days are sunny. Thank You
Which version of 2.2 are you using? I can't seem to find the quote you're referring to. Can you include a link to the document you're referring to?
Make sure that you are using the most recent version. I see that there are errata up to 2008.
I found the quote under this link: http://www.green.harvard.edu/sites/all/themes/green-ofs/theresource/leed...
Again, I am not sure if this is correct , but since we are still in schematic design these are early concept design simulations not related to the LEED requirement for now. Anyhow I would still like to know for the future.
Thank You
That is CI (Commercial Interior Template) with a date of 2008. That is why you are seeing daylight factorThe ratio of exterior illumination to interior illumination, expressed as a percentage. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis), and window height.. So is this a CI project or is this a NC v2.2 project? What version of LEED is the project registered under?
You need to ensure that you are using the correct rating system and most recent template or form. You should also review the most recent erratas for the version you are using along with reviewing any LEED Interpretations that may be relevant for your project.
As far as daylight factor calculation, that is done under the CIE unifrom sky. So your clear sky assumption would not be valid.
Is your space CI or NC? Is the credit registered in v2.2 or 2009? This link refers to a CI document and you are posting in the v2.2 NC forum.
Daylight factorThe ratio of exterior illumination to interior illumination, expressed as a percentage. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis), and window height. has a broader meaning than the way it is used in this document, so I see now what your question is.
You would not use Radiance (simulation ) to achieve the credit using this option. This is option 1 and simulation is option 2. The question about including direct sun or not does not apply to option 1, it is irrelevant.
Make sure that you are using the LEED version and product that applies to your project. The daylighting credit for NC, CI and EB can be very different and the daylighting credit has changed a lot since 2.2.
In version 2.2, they don't take high illuminance values into consideration, but they do in 2009. Good luck!
Car Repair Area
I am working on a 40,000 square foot car dealership - approx 20,000 sf is a car service area with minimal windows, but skylights. Would car service space be considered an occupied space?
Yes.
Are you registered under v2.2? (This is the v2.2 forum. Just curious.)
The project actually is registered under V2.2 - the owner has redesigned 3 times and this is the 3rd set of construction documents we have worked on for the same project.
To figure the square footage of the service areas I have excluded the drive aisles as circulation. Can I exclude the areas where the cars actually sit while being repaired or is that also considered regularly occupied space?
Wow.
Since the occupants are working on the cars, they need to be included. I'm not sure that they will allow exclusion of the drive aisles but if it's the difference between being eligible for the credit or not, you might as well try to leave them out. Have a good written explanation ready for the reviewer in case they have comments.
I recommend that you submit a floor plan that clearly marks the areas you are not including along with, as previously recommended, a well written narrative.
Can ask how much skylight glazing you have and the height of the car service space? What VLT are using for these skylights? I ask, because if you have the freedom to use skylights, then its about the amount and spacing of them to achieve the desired daylight levels. I understand that its not always that simple, but with the option in this type of facility you can achieve the credit without playing the regularly occupied not regularly occupied game.
Regularly Occupied Spaces - Lab Building
We are trying to determine the 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. for a lab facility. The layout of this facility includes both regular office space and lab space for each employee. The labs are broken down into main lab and prep lab. Additional support spaces include culture rooms and microscope rooms. As the scientistics will be "sitting or standing to work" in each of these spaces, are they all considered regularly occupied? I would assume the lab itself is regularly occupied but perhaps not the prep space (which could be comparable to the printer/copy station in an office). Does anyone have experience with this type of program and defining spaces?
According to the IEQ REgulary Occuppied matrix, lab spaces are considered regularly occuppied, but in health care facilities this can be reviewed under a space by space requirement.
Personally, if lab is conducting experiments by which daylight can effect the experiments or the materials, then it could be argued to be excluded. Usually prep labs are storage rooms in which experiments are prepped to be conducted in the lab, so these are regularly excluded.
simulation to verify prescriptive method
I have a project in which I am applying the prescriptive method, however, I want to check my results doing simulation. There is no columns neither walls. It is just an open space for office. In the prescriptive method I am using .5 for my TvisVisible light transmittance (VLT) (Tvis) is the ratio of total transmitted light to total incident light (i.e., the amount of visible spectrum, 380780 nanometers of light passing through a glazing surface divided by the amount of light striking the glazing surface). The higher the Tvis value, the more incident light passes through the glazing. and in my simulation I put 50% in the transmittance. The problem is that when I do the simulation (using SPOT) with that number (50%) the average in my area is 2475 luxMeasurement of lumens per square meter. and I think that the value should be around 500. Why is this happening?
What I am wondering is if my transmittance value is correct and if there is a factor of conversion from Tvis to transmittance.
Comparing values from the prescriptive path with simulations is like comparing apples to donuts. So i don;t know what you are trying to gain from this other than your project meets the credit requirements with both options.
Some more information would help to maybe help you. Orientation, glass to floor ratio, or wall, orientation, climate/location, ceiling height, and overall space dimensions.
Thank you so much for your comment. i think i will just leave it and trust my prescriptive method.
Anyone tried ID credit for dayligting > than 75% reg occ spaces?
Has anyone applied for and/or received ID credit for dayligting more than 75% of 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.? We have a building that provides daylight to 67% of all spaces including kitchen, bathroom, maint. workroom, offices and conference rooms. I'm just wondering if a project got denied such a credit what the GBCI's comments were denying such. OR if your project did get the ID credit we'd like to know your approach to documentation.
Thank you!
Debra Lombard, LEED AP, EMIT, EIT
Well 67% will not even meet the minimum level for one point. The 2.2 Reference Guide states that 95% is the minimum for any option used and must follow the requirements of the credit.
Simmulation help..
Hello,
We just recieved our reveiw comments back on one of the school projects that was done using Schools 2007. We did not get the daylight credit and got the suggestion to do simulation in addtion to clarifying the calculation method. We currently have the drawings in Autodesk Building Systems 2004, does anyone know of a program we might be able to make use of that will work with our current plans? Or has anyone had luck doing metering to off set the calculations method?
Thank you
Well you can use Ecotect which is an Autodesk product which you can import to radiance. Depending on the complexity of the design and the shape of the space, you could use SPOT. 3d Studio Max will also do simulations which is an autodesk product.
Todd, Thanks for your reply. I am looking to figure out some rooms that have borrowed lights. which seems to be a problem for this school. I will take a look at these programs though.
We have had luck with the measurement option. Not sure what you mean by offsetting the calculations. As you know, the glazing factorThe ratio of interior illuminance at a given point on a given plane (usually the work plane) to the exterior illuminance under known overcast sky conditions. LEED uses a simplified approach for its credit compliance calculations. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis) and window height. calculations cannot be used for borrowed light.
I will be curious to know what you decide on. Please post back when you do! Thanks
Tyler,
I see your issue now. So you attempted the credit using the glazing factorThe ratio of interior illuminance at a given point on a given plane (usually the work plane) to the exterior illuminance under known overcast sky conditions. LEED uses a simplified approach for its credit compliance calculations. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis) and window height. calculation, in which borrowed light scenarios can not be used. Depending on the number of spaces that have this scenario and if the project is already built, the measurement option might be more feasible. I'm assuming the learning curve on doing simulations and the time in which you need to re-submit.
Did you adjust your glazing factor calculations for compliant and no-compliant square footage to see if you earn the credit that way?
Tyler,
If the simulation you need is just a lighting simulation, I believe Autodesk Building Systems 2004 has a simple version of Autodesk VIZ that comes with the product. As long as your model is in 3D you should be able to do a daylight simulation and export it to an avi file.
Todd- Yes we did adjust the compliant and non compliant square footages and it still does not work. we are looking into some simulation programs but measurements seem a much easier way to go with the time we have. I will pass along the out come. Thank you for your information!
Tyler and Philip,
Unfortunately, Autodesk VIZ is not a valid software for LEED daylighting calculations, although I hear it does produce nice renderings. The only product from Autodesk that can produce these calculations directly is 3DS Max Design. Autodesk's Ecotect can export to Radiance (included) for these calculations as well. It's best if you know something about Radiance in order to produce the required LEED documetation. And I think you can use Autodesk's Green Building Studio service with Revit for export to Radiance too. Personally, I use AGi32 for LEED daylighting calculations.
See these links for some discussion on lighting calculation software.
http://www.leeduser.com/credit/CI-2009/IEQc8.1
http://www.leeduser.com/credit/NC-2009/iEQc8.1?page=3
Daylighting for Nurseries
We are working on a project that has 'Crib Rooms' which are meant to be sound and light isolated as they are meant for sleeping babies only. We are looking at this as a non-regularly occupied space becase it is essentially serving as 'baby storage,' and daylighting/views would not be beneficial in any way. Again, these spaces are only for sleeping babies, not for awake children. Please help.
Your argument is this. Describe what the space is for and how and why daylight is detrimental to the activity of the space. Technically that should be sufficient, but if this space has a bunch of windows and you are not considering it in the calcs, then that may be questioned as to why it was designed with lots of windows. If it is in the core, then it makes sense.
"baby storage" .... sounds adorable
Church
Should the meeting room for weekend use by a church be considered a regular occupied space? Yelena
Yes, a meeting room is like a conference room and must be included, even though it is only once a week. Occupants should still benefit from daylight and views regardless of the current frequency of use. This space may only be used once a week by the church, but what's to day that they do not rent it out to local groups on a more regularly basis.
Documentation
Our project was denied this point for being just under the threshold (74.98%). We were not going to change the design of the windows, but the owner has had to increase the width of a hand full of windows by 3" in order to meet code. The increase gets us to well above 75% and we are going to appeal, but are unsure of what exact documentation we should submit to prove that the windows are indeed going to be larger. I have a floor plan that outlines all of the windows which will be modified, and plan on getting a letter from the owner and architect explaining the situation. Would this typically be enough evidence to support our new design and new daylighting percentage?
Prudence,
The additional info you mention sounds like it would be enough to support the new percentage and not look like you were "cooking the books." It might also help to include any documentation of the code issue that triggered the width change such as plan check comments if available.
Change orders and invoices and contracts are also helpful to verify that the change has or will be occurring. The reviewer needs to take professionals or owners signature as the truth, but the other helps eliminate the doubt.
Do not remove previously submitted documentation. i suggest that you upload a copy of the original calculations. Provide a narrative explaining the reason for the appeal and what was done to earn the credit.
My suggestion is: Please don't forget your elevation drawings (before and after) and provide narrative that explains why you appeal the credit.
template
if i have a project with 14 floors that are typical do i have to submit space by space for each floor in the (supporting calculator) for documentation purposes?
No, do just one floor completely. Then in just the total for the other floors to be placed in calculations. Supply a narrative explaining your method along with floor plans that verify the floors are the same.
Gross Floor Area for calculating "regularly occupied gross area"
Does the thickness of the exterior wall get included when calculating the "regularly occupied gross area" on PI Form 3, Occupant and Usage Data? I did at first, as gross to me always usually does.
The inconsistency right now in my calc's is that I excluded the exterior wall area in the "supplemental daylight and views calculation spreadsheet" which I am using for IEQ 8.2. I am going for the prescriptive method. The problem is that I have 2' of strawbale wall on the exterior, which is significant amount of area not being carried over to the spreadsheet.
It doesn't seem like you should be including the exterior wall area when figuring daylighting, but I either I need to go back and exclude the exterior wall area from the PI form or add the exterior wall into the daylight zone area so that I get an accurate calculation.
Yes, regularly occupied area should really be Net, not Gross, so don't include wall thickness. This has confused a lot of people. Are you using certifying under version 2.2 or version 3 (2009)? The forms behave quite differently, and in version 3 you'll want to check via the "Feedback" link if there is an updated credit form and PI Form 3.
Thanks! That makes sense. I will just have to back out the gross area for walls, etc. and show under unconditioned gross area.
We are on Version 3. I'll have to check on the most current forms.
Daylight into interior space
I have a daycare center with a few occupied rooms falling in the center "core" surrounded by support space or classrooms. We have interior windows in the core room that allow you to see all the way out and plenty of windows on exterior walls. Some daylight is being provided but through the interior window. Are you able to count daylight into a core space through one window, as you are allowed to do with views?
Yes, you can count by using daylight simulation or measurement but you can't use the prescriptive as your calculation method.
By prescriptive method, do you mean calculations?
Our project is LEED Canada NC V-1. We have a MURB where the kitchen is in the core of the room. It has a doorway into a dining room with a large window, and a pass-though window into a living room with a window and a patio door. How can we show there is daylight in the kitchen? Could the openings be counted as vision glazing with TvisVisible light transmittance (VLT) (Tvis) is the ratio of total transmitted light to total incident light (i.e., the amount of visible spectrum, 380780 nanometers of light passing through a glazing surface divided by the amount of light striking the glazing surface). The higher the Tvis value, the more incident light passes through the glazing. of 1.0 since it is just an opening with no glass?
No, prescriptive method and calculations are not synonymous. I don't know about LEED Canada but for the US LEED, the prescriptive method is also Option 2 in the credit and it is not possible to show that you have daylighting in your kitchen using it. The only way is through a daylighting computer simulation (Option 1), measurement (Option 3) or both (Option 4). It doesn't matter what the TvisVisible light transmittance (VLT) (Tvis) is the ratio of total transmitted light to total incident light (i.e., the amount of visible spectrum, 380780 nanometers of light passing through a glazing surface divided by the amount of light striking the glazing surface). The higher the Tvis value, the more incident light passes through the glazing. is of your interior window. The fact that there is a any kind of opaque wall or divider makes the prescriptive method invalid.
Thank you Jill. We will run the calculation with the kitchen having no daylighting, and because it's a small area we may still make the 75%.
Regularly Occupied Spaces
Would conference rooms in Institutional buildings such as a Medical Office Building or a Research/Lab building be considered a regularly occupied space?
in my opinion, they will be considered as 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..
Tvis for 2 windows
I am trying to determine the TvisVisible light transmittance (VLT) (Tvis) is the ratio of total transmitted light to total incident light (i.e., the amount of visible spectrum, 380780 nanometers of light passing through a glazing surface divided by the amount of light striking the glazing surface). The higher the Tvis value, the more incident light passes through the glazing. with the use of 2 windows for an interior space. I have an office with an exterior window with a Tvis of 0.52. That office has an interior wall with windows with a Tvis of 0.89. I am trying to determine the combined Tvis for the windows for a cubicle area beyond the interior office wall with windows for this credit. Do I multiply the 2 together (0.52 * 0.89) to get a Tvis of 0.46?
Hi Mark,
Your question indicates that you are trying to use the prescriptive method to calculate the daylighting contribution of a borrow light, which you cannot do. You must you the simulation option for this type of set up. One reason is that the opening size of the both windows has a big effect on the amount of light that reaches the cubicle area. Does that make sense? The prescriptive method is meant only for very straight-forward calculations.
Thanks for your response Jill. I understand what you are saying.
option 1 calculation strategy
Hello everyone,
i'm working on my first leed project and as we are getting closer to final submittal date (in3 weeks), we are now starting to put these submittals together. i need some help.
we are working on a 2 story office project that's placed east and west direction. we have very large curtain wall facing south and north with very open floor plates using low parition walls/cubicules. most occupied areas are right next to those windows. however, some spaces are 15'-20' away from the perimeter. i'm sure we will get some daylight from 12' tall curtainwall windows. however, in order to calculate each space glazing factorThe ratio of interior illuminance at a given point on a given plane (usually the work plane) to the exterior illuminance under known overcast sky conditions. LEED uses a simplified approach for its credit compliance calculations. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis) and window height., i have to input glazing areas. if those spaces are 15'-20' away from windows, what should i put the glazing area?
do i have to go with option 3?,
i have 3-4 rooms will have full height partition, so i know i have to do them individually, however, most of the spaces(low partition/cubicles) are in one big area. can i treat them as one big space and do the calcualtion once?
Also, i have huge conference room with big windows on the north side. with option 1 calcualtions the room won't meet the minimum 2%. can i divide room into 2 spaces and made half of the room meets the min. 2% requirement? i'm not clear if this strategy allow with option 1 calculation.
Thank you very much,
Jin
Thanks, Jin
Hi Jim,
For each space, enter the actual glazing area. Draw lines across your elevations at 2'-6" and 7'-6" above the floor level. Calculate the glazing area between these lines and enter them in as view windows. Enter the area above 7'-6" as daylight glazingA vertical window area located 7'6" above the floor. Glazing at this height is the most effective at distributing daylight deep into the interior space. area.
If you do not reach 2%, scale back the floor area in your calculations until you do. This is the square footage that complies. This area must be 75% or more of 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. in order to get the point.
How low are your low partitions? I would say if they are at or below desk height, they are okay. Otherwise, you will need to use the other options (you can combine options.)
Good luck!
Hi Jill,
Thanks for your response. We have couple big open spaces with cubicles which divided by low partitions. They are really 50"-62" height. I was going to combine each cubicle spaces into one huge area. And calculate glazing factorThe ratio of interior illuminance at a given point on a given plane (usually the work plane) to the exterior illuminance under known overcast sky conditions. LEED uses a simplified approach for its credit compliance calculations. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis) and window height. using option 1 since they are movable partitions and furniture. Or should I completely take those spaces out of my calculation because of the height of movable partitions (being over 42" tall) even if they are 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.?
Jin, Sorry I mistook your name at first.
I'm not sure what you're asking about taking out the spaces - do you mean from the total regularly occupied space (ROS) or do you mean you will not calculate them? I don't see an exception here that would allow you to remove them from the total ROS.
Since your cubicle height is so tall, you cannot use the glazing factorThe ratio of interior illuminance at a given point on a given plane (usually the work plane) to the exterior illuminance under known overcast sky conditions. LEED uses a simplified approach for its credit compliance calculations. The variables used to determine the daylight factor include the floor area, window area, window geometry, visible transmittance (Tvis) and window height. method for calculation of the areas behind them. You must use either the simulation or measurement methods. It does not matter if they are moveable or not.
One more thing to note, depending on your building's climate, very large southern and northern curtain walls are not usually the best approach for energy use or daylighting and require careful glazing selection and shading design.
Start a new LEED comment thread