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 reducing energy use for lighting and for cooling. Increased daylight through increased vision glazing can help projects earn IEQc8.2 for access to views. Realizing the benefits of daylighting requires a collaborative design process.
Keep in mind that daylighting strategies must balance with other design goals. For example, you will want to provide enough glazing area for lighting, and 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.
This credit is easy to achieve for projects with large windows, open floor plates, and most occupied areas near the perimeter, but the documentation may be cumbersome for some large projects, depending on the chosen compliance path.
Compliance paths for IEQc8.1 have some key differences between v2.2 and v2009. In LEED-NC v2.2, Option 1: Calcualation allows you to show compliance with EQc8.1 by demonstrating over 75% of the regularly occupied areas have a 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 at least 2%. These glazing factor calculations consider window, wall, ceiling and floor areas, glazing type and VLT values.
In LEED-NC v2009, the glazing factor calculations option has been removed. In v2009, however, the Option 2: Prescriptive method provides a new approach to demonstrate achievement of the credit that considers many of the same factors as the glazing factor calculations from v2.2.
Another significant difference between v2009 and v2.2 is that v2009 allows for a combination of compliance path options to achieve the credit, via Option 4.
The USGBC's IEQ Space Matrix has detailed guidance that is helpful for any spaces you aren't sure about.
LEED does not prescribe the date or time, but it is recommended that they be taken close to noon under clear sky conditions, and, if possible, on or near one of the two equinoxes.
On LEED Online, in the credit, under credit resources.
You must submit a spreadsheet which contains all the information required on the calculator, and submitting the LEED Online calculator is recommended, but some teams have preferred to create their own, and have had them accepted.
No, the compliant square footage would be the worst-case scenario between the two times. For example, a 900 ft2 space located on the western side of a building is 100% compliant at 9 a.m. but only 50% compliant at 3 p.m. The compliant square footage in this case is 450 ft2.
LEED doesn’t require certain software to run the compliance calculation. However, the simulation should be able to run under “clear sky” conditions and calculate illuminance levels at 2’-6” above finished floor (AFF).
No. The only option in any of these cases will be the simulation or the measurement methods.
Focus on optimizing building orientation. Look for opportunities to optimize the glazing on each orientation to account for varying heat gain and lighting angles. When selecting a site, look for potential obstacles to daylight such as neighboring buildings, vegetation, and topography.
To reduce heating loads, use daylighting strategies in tandem with passive solar heating strategies, such as using materials with greater thermal mass and orienting the building for maximum solar gain.
To reduce cooling loads, use overhangs, lightshelves or fins, courtyards, and lightwells to block high-angle summer sun and low-angle morning and afternoon sun. These strategies also reduce glare and can improve daylighting by reflecting it deeper into the building.
Glare can become a problem if you have too much glass, or east- and west-facing glass. Using shading devices can allow projects to combat glare and still have large expanses of glazing. Daylighting from the north is consistent and high quality, while daylighting from the south is abundant and comparatively easy to control.
Large areas of glazing may cause unwanted heat gain and compromise energy efficiency. However, daylighting may require less glazing than you think—about 40% window-to-wall ratio may be more than you need. Glazing closer to the ceiling will have a greater daylight benefit than glazing near the floor—anything below 30 inches is considered to have no daylight benefit.
When programming, identify occupant lighting needs that could be met with daylight. The Illuminating Engineering Society of North America (IES) has prescribed footcandle levels for project types, occupant types, and tasks.
Set daylighting goals at the initial goal-setting workshop and incorporate them into the Owners Project Requirements document required for EAc1: Fundamental Commissioning.
Having two different sources of daylight in a space will help minimize contrast and shadows.
Identify regularly occupied spaces that need to be included in the LEED daylight calculation. Locate these spaces near perimeter glazing, courtyards, or other daylight sources.
Your project's regularly occupied spaces should be defined consistently across other LEED credits, especially IEQc8.2: Daylight and Views—Views.
Some applicable spaces may be exempt from the daylighting calculation if their uses are daylight-sensitive. Examples include museum or gallery spaces, auditoriums and high-security areas. If you have daylight-sensitive spaces in your project that you would like to exempt from the calculation, you must provide a detailed narrative explanation and exemption request along with the credit documentation. This requests are scrutinized carefully, however, and may not be successful.
Find out the Visual Light Transmittance (VLT) value of the glazing and enter it on the LEED credit form for each occupied space. The VLT is usually included with the glazing specifications.
Take the VLT of the whole window, not just the glazing, to account for shading from mullions.
More natural light is transmitted through glazing with higher VLT values, but higher VLT values tend to correlate with higher solar heat gain coefficients (SHGC). Assess the optimal balance of these values, along with U-value, based on the project’s climate and heating and cooling needs. These values are available on manufacturers’ specifications.
Hold an integrated design meeting with the architect, interior designers, mechanical engineer, lighting designer and the end users to discuss daylighting-related tradeoffs. Optimize glazing area while preventing excessive heat gain and glare; and use open space planning that allows for greater light transfer while preserving privacy.
Consider designing spaces with narrow floor plates so that most spaces are near windows and have access to daylight.
Prescriptive compliance paths for EAc1 (other than energy modeling) do not allow window-to-wall ratios greater than the relevant reference standard. Projects using these compliance paths are limited in the amount of allowable glazing area.
Designing for daylighting will allow you to reduce the number of ambient light fixtures and their frequency of use, reducing the cost of electric lighting both upfront and in operations.
Retailers may see increased sales linked with daylighting, according to studies showing a correlation between sales and natural lighting. Additional savings may be seen by employers through increased employee retention/satisfaction as well as productivity and reduced absenteeism.
Choose a LEED compliance path to verify that the daylighting meets the footcandle requirements of 25–500 footcandles for 75%–90% of regularly occupied spaces.
Explore a combination of daylight strategies such as space planning techniques, glazing selection, lightshelves and more.
Interior finishes can enhance or hinder daylight levels. Specify light-colored ceiling and wall paint to bounce light further into the room.
A common misconception is that a design needs to have more glass for effective daylighting. But effective daylighting can also be achieved with smaller apertures and glazing designed for specific indirect light, located high in a space to bounce light on to a ceiling.
Daylight sensors that adjust lamp brightness based on the presence of natural light can greatly reduce lighting energy loads. On average, commercial buildings use 25% of their energy for lighting. Dimming ballasts are more expensive and complicated to specify than stepped ballasts. Stepped lighting is considered less attractive because the dimming is not gradual but can do an excellent job reducing energy use.
Daylight controls, sensors, integrated blinds, and lighting controls come with moderate first costs but will bring energy savings over the long run.
Integrate glare control into the design.
Identify designs that combine glazing and building elements for optimum daylighting, such as window frames with integrated overhangs or light shelves. However, make sure that there is a thermal break (insulation) between the interior and the lightshelves, or these could become large-scale radiators of interior heat.
Glare can hinder the use of a space and be unpleasant for occupants. Daylight modeling can help project teams anticipate problem areas due to sun angles as they interact with the architecture. Exterior and interior shading along with associated controls can greatly reduce the effects of glare.
Fill out the LEED credit form with the names of the regularly occupied spaces and their square footage.
Simulation is the only way to account during the design phase for daylight designs that have many variables such as the use of lightshelves and light-colored interior finishes. The Glazing Factor Calculation path (Option 1) takes into account only walls, windows, floor and ceiling areas, and the measurement path (Option 3) will not help inform design as much.
Simulation is the only way to account during the design phase for daylight designs that have many variables such as the use of lightshelves and light-colored interior finishes. The Glazing Factor Calculation path (Option 1) takes into account only walls, windows, floor and ceiling areas, and the measurement path (Option 3) will not help inform design as much.
Use daylight simulation software to adjust daylight design as needed before it is finalized.
Coupling daylight modeling with energy modeling can help project teams make effective decisions about daylighting as it relates to other strategies like thermal massing, window area, window efficiency, and shading.
Simulation makes documentation easy by clearly indicating compliant areas.
Simulation is the only way to account during the design phase for daylight designs that have many variables such as the use of lightshelves and light-colored interior finishes. The prescriptive compliance path (Option 2) takes into account only walls, windows, floor and ceiling areas, and the measurement path (Option 3) will not help inform design
Daylight simulations may add an upfront cost but they offer fast payback in the form of effective daylighting strategy selection resulting in reduced energy costs.
Run prescriptive design calculations to verify that the required percentage of floor area meets the required levels.
This compliance path does not require modeling and can still help inform decisions during the design phase. However, the documentation and calculations can be complicated and time-consuming.
Measuring daylighting with handheld light meters can be time-consuming for large areas. Also, you are likely to need to defer this credit to the construction phase LEED submittal so that accurate light readings can be taken with interior walls in place.
Measurement can account for complex daylight designs but does not help inform the design process. It can only confirm compliance once the space has already been constructed. At that late phase, it may be too costly to make design changes to bring more floor area into compliance.
Measurement is a low-cost compliance method but may not help to optimize daylight during the design phase. An optimized daylight design can cut down substantially on lighting costs over the long run.
A hybrid compliance path may be the best solution for some projects. For example, if most of the regularly occupied spaces pass the calculation criteria in the prescriptive path, and a portion of the spaces fall short very narrowly or use strategies like lightshelves not accounted for by the prescriptive path, measurement of those spaces after finishes are complete could demonstrate that they are sufficiently daylit after finishes are complete.
For Options 1 and 2, enter square footage for the portions of the regularly occupied areas that meet the daylight requirements in the LEED credit form and upload all required documents to LEED Online.
Incorporate daylight-related items such as lightshelves, daylight sensors, and light-colored paint into specifications.
During the value engineering process, ensure that components critical to the daylight design, such as high-performance glazing and internal shading devices, are not removed from the project.
For Option 3, take daylight measurements with a hand-held light meter and record the values on a 10x10 grid plan. Enter square footage for the portions of the regularly occupied areas that meet the daylight requirement in the LEED credit form and upload all required documents to LEED Online.
Measuring daylight levels can be a time-consuming process in large buildings. Measurements are taken on a 10-foot by 10-foot grid, with four measurement points for each 10 ft2 section. Taking and recording each measurement takes about 30 seconds—not including setting up the grid—for a total of about two minutes per grid section.
Daylight sensors and other daylight controls should be added to commissioned systems for lighting for EAp1: Fundamental Commissioning.
Cleaning plans need to integrate the maintenance of interior and exterior shading and control dust so that reflectivity is not compromised.
Daylighting controls can be set and tailored for each space. The facility manager or another designated person should be in charge of adjusting the settings to meet the needs of occupants.
Educate staff and occupants on daylight-related and glare-control technologies. Some daylighting controls such as shades or blinds may require occupant operation, and without instruction, may not be used properly, resulting in the building not operating as designed.
Excerpted from LEED 2009 for New Construction and Major Renovations
To provide building occupants with a connection between indoor spaces and the outdoors through the introduction of daylight and views into the regularly occupied areas of the building.
Through 1 of the 4 options, achieve daylighting in at least the following spaces1:
Demonstrate through computer simulation that the applicable spaces achieve daylight illuminance levels of a minimum of 10 footcandles (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.) (108 luxMeasurement of lumens per square meter.) and a maximum of 500 fc (5,400 lux) in a clear sky condition on September 21 at 9 a.m. and 3 p.m.
Provide glare control devices to avoid high-contrast situations that could impede visual tasks. However, designs that incorporate view-preserving automated shades for glare control may demonstrate compliance for only the minimum 10 fc (108 lux) illuminance level.
Use a combination of sidelighting and/or toplighting to achieve a total daylighting zone (the floor area meeting
the following requirements) that is at least 75% of all the regularly occupied spaces.
For sidelighting zones:
For toplighting zones:
Demonstrate through records of indoor light measurements that a minimum daylight illumination level of 10 fc (108 lux) and a maximum of 500 fc (5,400 lux) has been achieved in the applicable spaces. Measurements must be taken on a 10-foot (3-meter) grid and shall be recorded on building floor plans.
Any of the above calculation methods may be combined to document the minimum daylight illumination in the applicable spaces.
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 high-ceiling reflectance values; ly, additionally, automatic photocell-based controls can help to reduce energy use. Predict daylight factors via manual calculations or model daylighting strategies with a physical or computer model to assess footcandle levels and daylight factors achieved.
This updated version of the 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. Up to date, 2nd Edition.
This is the American industry authority on lighting levels and energy use. The Illumination Engineering Society of North America (IESNA) publishes several design guides for recommended lighting levels, daylighting and much more.
This is a database of window brands, VLT and U-values for different glazing manufacturers. The program provides a versatile heat transfer analysis method.
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.
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. This is the 1st edition.
This is a comprehensive list of modeling tools compiled by the U.S. Department of Energy.
This daylight modeling tool is widely accepted in the lighting industry.
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.
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 is used to create 3-D graphic models that can help in your daylighting analysis and documentation.
This is a lighting group that has published research on the effects of daylighting.
This is the organization that sets lighting standards. The IES also works directly with ASHRAE to develop energy standards.
This is a case study for the effects of daylighting on productivity in schools. Prepared by Heschong Mahone Group for the California Energy Commission.
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.
This is a case study for the effects of daylighting on productivity in schools. Prepared by Heschong Mahone Group.
To use the prescriptive compliance path, follow a process like the one in this example, which achieves the credit using a combination of side and top lighting.
Take daylight measurements with a handheld light meter and record the values on a 10x10 grid. Enter square footage for the portions of the regularly occupied areas that meet the daylight requirement in LEED Online.
Sample LEED Online forms for all rating systems and versions are available on the USGBC website.
Documentation for this credit can be part of a Design Phase submittal.
We submitted for this credit using the results from the REVIT 2016 daylight analysis tool. Both the Lighting Analysis plans and the Room Schedule Threshold results were submitted as part of the documentation.
The credit was denied. The reasons given included one, that some of the spaces had simulated illuminance levels of less than 10 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.. Our submitted documents include lighting analysis plans that clearly showed NONE of the spaces mentioned in the Review comments had illumination levels below 10 fc. Another reason for denial of the credit was that the interior renderings did not show shading devices. Well, the renderings were created showing the shading devices concealed in the pockets. If the intention is to indicate shading devices, we could have included the drawing sections that call them out.
We are mystified.
How do we question this? We don't think it falls under an appeal, as we are not requesting a different interpretation. We think the ruling is incorrect.
Thanks in advance for any helpful suggestions!
I would suggest you email them this question through the contact us form, stating the evidences you provided. I have had some review comments where it also seemed that there was a mistake and have always received a clarifying response on what they are looking for.
If this was just a preliminary review, provide a review response and outline each issue and be very specific with your response. If this was a final review, then submit a project team inquiry outlining the issues.
I will say that the comment in regards to the light levels is a mistake. I can see where the reviewer may have some justification to question the shading devices with a rendering but to me it shows that the reviewer may not have a working knowledge of renderings and the simulation program. Shading devices are not required for daylight sims in v3, so why would you expect to see them in the daylight rendering. Now if you submit an actual image and don't see any, that is a legit question.
For a warehouse, can I deduct the permanently fixed high racking coverage area from 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.), and focus my 75% daylight coverage on the aisles and landing spaces only? I say yes. Right?
using TDD's & simulation.
( I can't believe I don't know this answer, forgive me if this is a regularly asked question, and I missed it in a search result. I have read several posts and I am not sure I am clear.)
Permanently mounted rack system that cannot be occupied by a person can be excluded from your regularly occupied floor area calcs. An yes, you will need to show the illuminance levels in the aisle.
Also, as noted in the regularly occupied space matrix dated April 2015, an inactive warehouse/storage does not have to be included in the credit. So you could exclude the whole area if it is not considered active.
First off I have a slight confusion about whether library stacks should be considered non regularly occupied area or a regularly occupied area with movable furnitureMovable furniture and partitions are those that can be moved to provide access to the view by the user without the need for tools or assistance from special trades and facilities management..
If the stacks are not bolted down but would still require staff to move them would they be considered movable furniture. Also would the area under them then be regularly occupied because the use of that area is thus flexible. The concern being that the library will eventually move away from books on shelves and utilize the space differently. So would this area then be regularly occupied with movable furniture that is not modeled and does not impact the simulation. I suppose the situation is similar to an open plan office with system furniture that could be reconfigured by building staff over time.
On the other hand if we are concerned only with the current appearance of the space this would be unoccupied given the category space matrix. But should the geometry of the stacks be included in the simulation in order to influence the daylight penetration into the rest of the space. Similarly would they be present for 8.2 views calculations.
I would imagine that this is a judgement call on using the prescribed usage or constructing a narrative to describe the design intentions. If anyone has had experience with this any advice would be much appreciated.
It really is a judgement call, but best practice would be to include them. We include the stacks in our daylight simulations. We also include as much of the movable and fixed furniture in our sims. It is how the space is going to be used, so that's what we want to see. Interior designers can be helpful or detrimental to your daylighting strategies. It is best to have them part of the early discussions in regards to furniture layout and material and color selections. I have seen on more than one occasion where a space was designed to be well daylit, that did not consider any furniture or colors, get ruined by color and furniture selection that basically negated all the daylighting strategies.
All the projects that we have submitted that included a library, we have kept the stacks in the calculations and kept them included in the overall regularly occupied area. The main reason is that we design the space so that the stack area would also be daylighted. The key is that you design the space to meet your required performance. So if you want it to be daylit, you design it to be daylit. If you design and then see how it works, then you become reactive instead of proactive and then you begin to look at how you exlcude things. .
Technically, if they are not permanently fixed, then they can be excluded, but the area they would occupy is considered regularly occupied and would have to meet the daylight requirements.
With EQc8.2, we orientate the stacks so that they are perpendicular to the window wall. This helps with daylight penetration and views.
First off, I have had a very hard time finding information to help complete this Credit's documentation. There are terms that are undefined or have one meaning in regards to this Credit but other meanings in the Architectural realm. Are there any examples that a first time documenter could look at to reverse engineer the process that is required to correctly document this credit?
With that said, I have a question regarding the Floor Area. At first I assumed that it would be the actual floor area but after calculating many of my rooms, I found that most of them were not meeting the requirements that determine if those rooms would apply to the Regularly Occupied Daylighted room area. So I read further into the other options for documenting this credit and I found that the Simulation Option requires that you record the light levels at 30" AFF. So my question is just that, Can we/ should we determine the Floor area at a certain height AFF, or does this number need to come from the Floor Level. If I take the area at 30" AFF, Most of my rooms are applicable.
Thank you in advance for your time and attention to this matter.
Lets go in reverse, by answering your second question first. Why, because you need to have your regularly occupied area established before starting any of the options with the credit.
Make sure your regularly occupied space is established. This is different than your gross area. It is determined at the floor, not 30", and is the floor area between the walls. the 30" is for where the one should set their calculation grid or take their hand measurements from. Circulation areas, or areas within a space where permanently mounted equipment may be placed does not count. Refer to the Regularly Occupied Space Matrix which can be found in the resource tab of the credit in the credit library on the USGBC website.
Now that you have the regularly occupied area established, you need to establish the daylight zone. The daylight zone is the distance from the window wall which will or may receive adequate daylight levels. If there are no exterior overhangs or interior surfaces that are below the head height of the window, then you use times the window head height to establish the daylight zone depth. You should show this is in a section and on a plan. Note the daylight zone in the calculator. Then complete, the rest of the calculations.
Daylight zones should be established in a room when the window size or properties changes. In a space with more than one window wall, a daylight zone needs to be established for each wall.
I do not know of any publicly available examples for you to review.
So, back again to ask another one. We are ever so close to reaching 75% threshold and without having the engineers run daylight models or measure the space I'm trying to pick up any space we can. As I was reviewing the plans again, I realized that we did not count 3 reception areas in the main building lobby that will be staffed full time. The lobby is a massive circulation space and the desks sit in the space. How would we go about calculating the reception area space? would we just calculate the adjacent desk area? or would we split it into a "zone" that is basically the entire column bayA bay is a component of a standard, rectilinear building design. It is the open area defined by a building element such as columns or a window. Typically, there are multiple identical bays in succession. at that location? Any advice would be a great help! I have a diagram of what I mean if that would be beneficial. Thank you!
You would have to show that the reception desks fall within the daylight zone, 2H, from the window wall, then as you noted, apply the amount of glazing from that bayA bay is a component of a standard, rectilinear building design. It is the open area defined by a building element such as columns or a window. Typically, there are multiple identical bays in succession. to the reception desk area. Include where the person sits.
It may make the space over daylit since you are not including the lobby. Now lobbies are not considered regularly occupied in the space matrix, but that does not mean that may not have spaces within them that are used for certain things. YOu could include the lobby in the calculations and then just group the reception desk with the lobby space.
Again, the prescriptive method is just for simple spaces and you begin to really muddy up the waters when you try and push it.
The LEED reference guide does not indicate that the occupied space (the reception desk in this case) needs to be within the 2H zone as you stated. The guide only mentions that a ceiling cannot impede on the angled connection between H and 2H.
If the reception desk is not within the established daylight zone, which is determined by either 2 times the window head height, or using the 63 degree angle, then you cannot say that the reception desk will receive adequate daylight using the prescriptive method. It is just like any other space, any area out of the daylight zone cannot be considered daylit and therefore will go against achievement.
What is the distance from the window wall to the reception desk and what is the window head height?
We just received our design credit responses and used method 2 - Prescriptive. We have a 3 story cafeteria space within a 30 story office building.
The lowest level butts up to the 3 story glass wall on the exterior and the 2 levels above are held back from the 3 story glass wall by 20'-0"-ish. We are getting a comment saying that these upper cafeteria levels do not count. I know that above in the explanations, it mentions borrowed light from an atrium is not allowed, but these spaces are open to the adjacent glass, just not touching the glass exterior wall.
Is there no way for us to respond to this comment with a narrative explanation that the spaces are daylit, showing a section with light hitting the surfaces of the mezzanine levels? These levels are open and only separated by a railing, not another glass wall falling under the borrowed light definition.
thanks for any comments you might have.
I will agree that the upper spaces do not fall under the specific definition of borrowed light but I can see why the reviewer may have used this language.
The prescriptive method is meant for simple geometries and daylighting scenarios because it is all based on formulas. Your situation is not one that would be considered simple. I think the reviewer should have provided a specific reason for saying why they cannot be included or given you a possible method to demonstrate how. Your situation is one that would require more than a narrative to show compliance with the option 2.
From a professional side, these spaces cannot technically be included in the prescriptive calculations. You would have to show how much of the 3 story curtain wall glass is allotted to each level. You would then need to establish the depth of the daylighting zone from each allotted area of glass. From the sounds of each, with each level being at 20 feet from the glazing , they might be too far away to have any sizable daylight zone. You cannot use all three floors of glazing for each level, that might actually have too much daylight. What I just described, I have never seen done or attempted with option 2. As you can see, it is complicated and does fit into the simplicity method that option 2 is meant for. You could try it and make a case and see what happens or, do a project team inquiry and ask specifically why the spaces are rejected and what must you show to demonstrate compliance.
Personally, I would have done simulations or at least do measurements. The prescriptive is too simple for the scenario you have.
Please follow up if you decide to do an inquiry and what the reviewer asks for or whatever path you choose.
Thanks for the response - we are the LEED sub-consultant to the LEED consultant and were instructed to use method B. I agree, simulation may have saved time - and after all this, we may have to do some simulation of a few spaces to achieve our 75%. The Leed reviewer indicated that we could supplement the diagrams with a daylight model for those spaces to kick us over the 75. From the beginning though, everyone thought option B would be a slam dunk!
Working on a conference center, we are close to get to Gold Certification by 2 points. Our chance to get closer to it is to get 1 pt for Daylight, and most probably another one for Views.
The project has an underground ballroom which makes almost half of the project area and could or couldn't be considered as a regularly space area since this space type isn't mentioned in the LEED Space Types Matrix. This space is a renovation, has no windows and is meant for projections, seminars, meetings and even reception with no intent to use daylight.
Is this something arguable case so we can exclude the space, minimize our denominator in the calculations and maximize our chances to get a better ratio overall just accounting for daylight in the upper levels designed to be exposed to the exterior environment?
Thank you all for your feedback
Unfortunately, I can't tell you what you hope to hear. I've seen many, many cases where teams have tried to argue that they don't want to use daylight in a space (even a military dark-room simulation space) and it does not fly for this credit. Since credits are optional, it makes sense not to give the daylighting and views credit to a building that is mostly underground (I know yours isn't, but I hope you can see my point.)
How confident are you in all of your other credits? I see teams trying to extend themselves to reach the exact number of credits for the next highest rating, only to have one or two of their credits not come through.
The activities of the ball room; meetings, receptions, seminars fall under space types in the Regularly Occupied Space Matrix that require those spaces to be included in EQc8.1. Spaces with AV and projections cannot be excluded, classrooms have AV. Only rooms whose only activity is video conferencing and labeled as such on the plans can be excluded.
Not every project can earn every credit and renovations make LEED harder to achieve than new construction because it is what it is.
Jill and Todd,
Thanks for your replies, that helps to understand.
We are pretty confident in the other credits so the thought was to push to get the daylight ones since the project is made elsewhere to get as much daylight as possible on perimeter spaces. To that point, perimeter spaces are made of "prefunction areas", "lobby" and "terraces" which are used as an extension of the ballroom during events. One might think they are transient spaces which can be the case, but they have multi purpose functions.
Do you think they would fall under "regurlarly occupied space" per your experience? Our intent is that they should.
Thanks again for your reply in advance.
Professionally we know that these spaces are used for things other than circulation and transitions. An so we should provide these spaces with views and daylights. Where do people go when they get out of the conference room after watching a power point presentation for an hour, to the window wall. Yes, from the professional side.
For LEED, its how the spaces are labeled on the plan. Lobbies are considered or not considered regularly occupied based on the type of the project. The regularly occupied space matrix shows this. Terraces, not listed in the matrix, but will be reviewed by the reviewer based on its location. So if you an area listed as Terrace in a large main corridor, it might be looked at as a break out area or it may not.
There is nothing that states you cannot include a space if it can be excluded as noted in the matrix, for most spaces. Circulation areas will get called out. But if you have provided daylight to the space, then include it. But you need to be consistent with it.
Hope that helps.
Thank you for your in depth explanations, really appreciated. There are so much grey areas sometimes that this is hard to make a best judgment call.
I hope we will find a solution if we are short on getting 75% of daylight overall, otherwise, that might be a lost battle since I don't think we can make it with the ballroom being included. I will get back to this topic if I see hope in it!
We have a project that is going to use a combined approach due to overhangs and the prescriptive calcs not providing enough SF. I have casually measured the spaces and we exceed 20fc. We have one large room that I can easily do a 10 ft grid on, but we also have 10 small offices that are probably narrower than 10ft. How is it recommended that I measure this space? Can I make a smaller grid, so we can include an adequate portion of these offices? Or do I just measure in the corners? (or a set distance off the corners?)
The 2010 addenda states that at least 4 measuring points are required per space. I know its an overkill in 10x10 spaces but that is what is needed.
Do Glass Doors count as windows and require automatic glare control?
Doors do not count as windows but if you are using the glazing within the door to achieve the desired daylight levels, then you will need some form of glare control.
Automatic glare control devices are not required, it is optional, but some form of glare control is required. So for the door, you could just have some type of interior blind installed.
I'm going to do the measurement method for the first time, and was looking into using a light meter app on my phone to do it- would this be acceptable? Does anyone have any experience using a light meter phone app to get readings for this credit?
Although I have found some light meter apps to be remarkably accurate and useful for informal measurements, I don't recommend it for this application. Somewhere in the fine print I believe a "calibrated" light meter is required. Not 100% sure but it seems likely. We send them in every couple of years to be re-calibrated.
Sara, there is no fine print in the v2009Reference Guide or the addenda, that I can find that suggests or requires the use of a calibrated light meter. There is nothing that the you must provide or the reviewer can ask for that confirms the use of a calibrated meter. The measurement option really is one the most lenient and flexible credits. As long as you have 4 measurement points per space you should be fine.
On the professional side, I would only consider an app valid if I did a side by side comparison with a meter and would personally just use a meter. But there is nothing that would stop you from using an app, I would just validate it with a meter first.
Joyce, would you be willing to share which apps you have found to be accurate? I've tested six different apps and have found them to be nowhere near accurate as compared to my calibrated professional meter.
As to the question, I'm disappointed if there is nothing that mentions a calibration requirement, but not that surprised. I think this goes in the pile of questions with the answer "use your professional judgement and reputation" on determining the appropriateness of your light meter.
Alas, just compared the app on my current windows phone to a calibrated meter reading and it failed miserably. Last test was 2 yrs ago with an iPhone app and results were within 5fc for daylight harvesting calibration. No good for emergency egress lighting. I'm with you. Let's stick with professional calibrated meters whether or not LEED requires it.
Can we use the prescriptive method if there is a fixed exterior brise soleil in the façade?
Can we use the 63 angle from the brise soleil to exclude part of the daylight area?
If the brise soleil runs the entire height of the window, no. The prescriptive method, in its simplicity, is based on the windows access to the sky vault. That is why the 63 degree angle comes into play when determine the daylight zone depth. With a secondary façade, even like the breis soleil, the prescriptive method cannot consider this.
1.Measurements were disappointing July 15 because shading structures are doing their job and blocking direct sunlight - a blessing in Southern Arizona.
Should we wait until the nx. equinox to measure again?
2. How do you recommend we address temporary obstructions, Streetcars in work areas, shadowing inspection area? Should we return and take measurements of inspection area after car moves there from work area?
There is no specific method or time when it comes to measurements if you are just trying to document the credit. It's also hard to say when you should take measurements again without knowing more about the project. If the project is not that big, then i would take measurements at or around the equinox, in the morning, noon, and then afternoon.
I would definitely ensure that any obstructions or things that will not be there once occupied are removed. Your measurements should be taken under conditions of regularly occupancy.
Can I do prescriptive method of calculation for an open floor plan if the N+W glazing walls of the building have a 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 38% and the South + East glazing walls have a Tvis of 56%?
Each façade will have its own daylight zone, so for that floor you will have N,S,E,W with their own determined daylight zone and you will use the corresponding VLT. Each façade gets it own line in the calculations. I would divide the floor area appropriately for each façade.
I'll give that a go.
For option 3, do measurements have to be taken more than once?
And the measurements can be taken any day of the year? Is there a specific methodology to follow apart from the height and distance requirements?
There is no specific methodology to taking measurements. They do not have to be taken at a certain time, on a certain day, or under any specific weather condition. Just make sure you have a measurement every 10 SF.
I would suggest that you take them at noon or close to it under sunny skies.
If you are taking measurements to be used to guide future design decisions or make changes, I would say you take a series of measurements under different sky conditions and at different times.
I don't know if anyone has asked this question or not, it is a rather unique situation. Our project is a technical college and this particular building's academic programs revolve around teaching energy efficiency. Our mechanical room is designed such that students will not only have access, but will monitor the buildings systems and record changes. So in essence this room is both mechanical ( which usually not counted as regularly occupied) and laboratory (which would be considered regularly occupied). As with most mechanical rooms it has no day lighting. Wondering if this room would still be exempt or I should count 1/2 with a narrative?
Any thoughts on this?
I would say that it could still be exempt as long as the students just go in there, take the readings, and leave. Even if they go in there on a daily basis, they are only going in there for readings, so if that's the case, I would not worry about it. If you have the space laid out in a way that you are holding classes on a regular basis, then you are on a fine line. Now if the students go in there for say maybe one or two classes a semester, I would not worry about it.
I'm assuming with this type of project you will be going for green building education or the school as tool credit. So you will be discussing how the school is used to teach. As long you clarify in that documentation how they monitor the systems, you should be ok.
If part of the building area passes at 9am but does not pass at 3pm does that mean we cant use that 9am area for that time. Basically what I am getting at is that if at 9am 80 percent of the building is withing the 10-500 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. range and at 3pm the building is also at 80% but some of the areas are in different locations. Meaning that they dont share all the same area. Would this still work. Or is the area that does not pass at 3pm disqualify an area that would have passed at 9am?
Thanks in advance
Lets look at this by a room to room basis and not as a whole building. You will be completing the calculator by listing individual spaces, so this is the best way to think about it. So if a room is 90% compliant at 9am but only 80% compliant at 3pm, then the room is 80% compliant.
The lowest percentage at either time is the compliant square footage that is used in the calculator. So if a space is not compliant at 9am, but is at 3pm, its not compliant at all.
Hope that helps!
Yes it does very much. Thank you so much!
Where would I find the Supplemental Daylight and Views Calculation Spreadsheet for v2009 (LEED Online states it's "found under 'Credit Resources'")?
Under the old platform, credit resoources was located right on the credit page. Under the new platform, click on credit library, then scroll down to the daylight credit and click on that. In the credit, click on resources and that is where you will find the views and daylight calculator for download.
Let me expand that a little more. In the new platform, in the project, click on the credit, underneath the credit you get 5 options, form, upload, resources, credit library. That is where you click on the credit library.
You could also such go to the credit library through USGBC's website and download it.
Can anyone confirm if the in-house plugin for Revit 2015 will be accepted for IEQc8.1 simulation?
I do not see any issues that would not keep the results from being accepted. There is no specifc guidance in v3 as to which simulation program is required or what the simulation program must do. With the Revit daylight analysis, you will get the time in point calculations,it will provide the floor plan showing the daylight sim results, and it will provide a spreadsheet showing the actual fc reading per room.
I know that glare control is a requirement for each window. The reference manual gives a list of these to be: fixed exteror shading devices, light shelves, interior blinds and louvres, fritted glazing and electronic black out glazing.
Has anyone ever heard of an instance where glazing with a lower LT could be considered as glare control?
I personally have not seen anyone make a successful argument for LEED. Now we can discsuss how low VLTs do help reduce or eliminate some forms of glare in the interior and how that effects daylight and what not, but unless you get a LI (CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide) passed through the TAGLEED Technical Advisory Group (TAG): Subcommittees that consist of industry experts who assist in developing credit interpretations and technical improvements to the LEED system., you are going to need something else.
Personally I believe that only form of glare control device that should be accepted is some form of movable blinds or shades. Exterior shading devices or lightshelves will only block the sun for certain times and angles. The only way to cover all possible forms of glare and possible occurrences is with movable blinds. The other reason is for if and when the space becomes over illuminated with to much daylight, it is possible in spaces that are not designed with daylight in mind. Then what are the occupants left with?
When working on leedonline for this credit, we are told to Download, complete and upload the Supplemental Daylight and
Views Calculation Spreadsheet (found under "Credit Resources").
The problem is, we cannot locate where the Credir Resource is or where to download the spreadsheet. Anybody can help?
We found it already, thanks.
I abhor this new layout. I could not find it either and after hours, discovered it here: http://www.usgbc.org/node/2614118?view=resources
I realize you have already found it but others may be struggling with the same issue so I thought we could help them.
I am documenting this credit using the simulation method. For many of 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., the rooms are above the 10fc requirement except for a small corner of the room. Based on reading this thread, my understanding is that the % of the room that is daylit can be counted towards the total required daylit SF. Is that correct?
Or if a room has an area that is below 10fc, then is that entire room disqualified? Thanks for your help!
With the simulation method, what ever area in a room that is above 10fc and below 500 fc at both 9am and 3pm, that is your compliant square footage.
For example, a 200 sq ft room has 190 sq ft within the range at 9am and 180 sq ft within the range at 3pm, then your compliant square footage for the space to be entered into the calculator would be 180 sq.
If some of the area of a room is below or above any limit, it does not disqualify the entire space, only the sq footage.
Hope that clarifies your issue.
Are rolling shades mandatory when doing the prescriptive method?
Some type of glare control is required for all methods. Rolling shades are one type.
Although the October 2013 Matrix, does not allow any patient rooms to be without daylighting/ views, I believe these rooms could be eliminated due to the nature of their process. Has anyone dealt with these rooms before in a medical center setting?
Because of the required shieldingShielding is a nontechnical term that describes devices or techniques that are used as part of a luminaire or lamp to limit glare, light trespass, or sky glow. for a MRI room and what occurs during the scanning, of both MRI and CT, you can exclude these rooms from the calculations.
We have incorporated daylighting into CT rooms in the past. Check on the distance/elevation of required shieldingShielding is a nontechnical term that describes devices or techniques that are used as part of a luminaire or lamp to limit glare, light trespass, or sky glow.. You could potentially just use top lighting or if adequate distance is provided, side lighting. Daylight in these rooms is highly desirable for the staff and patients.
Should an area designated for hot desking be included as a regularly occupied area? No single user will spend more than one hour per day at these workstations.
Yes, its still considered a workstation, and why wouldn't you want these spaces to have daylight.
Todd, it is a workstation, but why would it be considered regularly occupied if it doesn't fulfill the one hour requirement?
I agree that I personally would want these spaces to have daylight.
Paul, these are very hot hot stations!
Jill, there are numerous spaces listed in the regularly occupied space matrix that you could easily say, will be occupied for less than one hour and therefore are not considered regularly occupied. But to avoid the continuous argument as to what is and is not regularly occupied, they listed a bunch of spaces. Well, they haven't listed every single type of space out there. So you take these spaces that are not specifically listed in the matrix and then group them with what type of activity occurs in this space. Hot desk, people getting together to discuss items, review documents etc. etc. You could say the same for a conference room. You could argue they are different and that a hot desk is only meant for "quick" get togethers, where as conference rooms are not. But I could argue that you could meet at a Hot desk for more than an hour. Where are hot desks typically located? Within an open office plan off to one side where teams can gather. How can you not list that as regularly occupied, its not circulation.
So it is best to place the space based on activity rather than argue that it is "meant" to be used for less than one hour, even though it could be used for more than hour.
You can make
Thanks. Also, it was good to remind myself that the one hour per person isn't a requirement as much as a guideline.
Paull, I think Todd is right and if you're going to try to exclude these spaces you're going to have to provide a very strong case as to why no one would want to use them for more than an hour. When I think of 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. based on the time guideline, I think of a corridor, as he mentions, or a small copier station for example.
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