NC-2009 IEQc8.1: Daylight and Views—Daylight

  • NC&CS EQ8.1 Type3 Daylighting Diagram

  • 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 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.

    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 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.

    Documentation can be cumbersome

    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.

  • Changes in LEED-NC v2009 versus v2.2

    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.

  • FAQs for IEQc8.1

    What spaces are considered regularly occupied and must be included in the calculations?

    The USGBC's IEQ Space Matrix has detailed guidance that is helpful for any spaces you aren't sure about.

    When should daylight measurements be taken?

    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.

    Do I need to have glare control devices?

    Yes.

    Where can I find the Supplemental Views and Daylight Calculator?

    On LEED Online, in the credit, under credit resources.

    Do I need to submit the Supplemental Views and Daylight Calculator?

    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.

    Can I average the compliant square footage between 9 a.m. and 3 p.m. for a space and use the average as the compliant square footage?

    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.

    What daylight simulation software can I use for LEED compliance?

    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).

    Can I use Option 2: Prescriptive method if I have:

    • Windows with different Tvis values within the same wall width?

    • Windows with different head heights within the same wall width?

    • Windows with different sill heights (and above 30”) within the same wall width?

    • Windows with permanent shading devices?

    • Skylights with different Tvis values within the same ceiling area?

    • Clear skylights?

    • Light that is transferred between one room to the next through an interior wall opening—glazed or unglazed?

    • A Tvis/WFR value above 0.180?

    • Rooms that borrow light from an atrium?

    • Clerestory windows?

    • Roof monitors?

    • Tubular daylighting devices such as Solatube?

    • Roof overhangs?

    • Shared daylighting scenarios?

    No. The only option in any of these cases will be the simulation or the measurement methods.

Legend

  • Best Practices
  • Gotcha
  • Action Steps
  • Cost Tip

Pre-Design

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  • 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.

Schematic Design

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  • 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.

    • Option 1:  Computer daylight simulations can be the most effective design tool, but hiring a modeler will be an upfront cost.
    • Option 2: Prescriptive LEED calculations can help inform design, but not as accurately as a daylight simulation. The calculations can be time-consuming for large buildings, but do not require expert help.  The prescriptive calculations will only take window, wall, ceiling and floor areas, and glazing type into account, so other methods that help daylighting such as lightshelves and light-colored finishes won’t be factored in.
    • Option 3: Daylight metering can be an inexpensive way to measure actual footcandles, but won’t be accurate until construction is complete, when the results cannot help to inform design.

Design Development

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  • 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.

  • Option 1:  Computer Simulation

  • 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.

  • Option 2:  Prescriptive Design

  • 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.

  • Option 3:  Measurement

  • 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.

  • Option 4: Combination

  • 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.

Construction Documents

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  • 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.

Construction

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  • 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.

Operations & Maintenance

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  • 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.

  • USGBC

    Excerpted from LEED 2009 for New Construction and Major Renovations

    COPYRIGHT © 2009 BY THE U.S. GREEN BUILDING COUNCIL, INC. ALL RIGHTS RESERVED

    IEQ Credit 8.1: Daylight and views - daylight

    1 Point

    Intent

    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.

    Requirements

    Through 1 of the 4 options, achieve daylighting in at least the following spaces1:

    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. Points
    75% 1


    Option 1. Simulation

    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.

    OPTION 2. Prescriptive

    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:

    • Achieve a value, calculated as the product of the visible light transmittance (VLT) and window-to-floor area

      ratio (WFRWindow-to-floor ratio (WFR) is the total area of the window (measured vertically from 30 inches above the finished floor to the top of the glass, multiplied by the width of the glass) divided by the floor area.) of daylight zone between 0.150 and 0.180.

      • 0.150 < VLT x WFR < 0.180


    • The window area included in the calculation must be at least 30 inches (0.8 meters) above the floor.
    • In section, the ceiling must not obstruct a line that extends from the window-head to a point on the floor that is located twice the height of the window-head from the exterior wall as measured perpendicular to the glass (see diagram on the next page).


    • 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 0.150 value.

    For toplighting zones:

    • The toplighting zone under a skylight is the outline of the opening beneath the skylight, plus in each direction

      the lesser of (see diagram below):

      • 70% of the ceiling height,
      • 1/2 the distance to the edge of the nearest skylight
      • The distance to any permanent partition that is closer than 70% of the distance between the top of the partition and the ceiling.


    • Achieve skylight coverage for the applicable space (containing the toplighting zone) between 3% and 6% of the total floor area.
    • The skylight must have a minimum 0.5 VLT.
    • A skylight diffuser, if used, must have a measured haze value of greater than 90% when tested according to ASTMVoluntary standards development organization which creates source technical standards for materials, products, systems, and services D1003.
    Option 3. Measurement

    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.

    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.

    Option 4. Combination

    Any of the above calculation methods may be combined to document the minimum daylight illumination in the applicable spaces.

    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 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.

Technical Guides

IESNA Recommended Practice of Daylighting—Daylight Design Guidance

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.

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.

Prescriptive Compliance

Option 2

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.

Daylight Measurement

Option 3

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.

LEED Online Forms: NC-2009 IEQ

The following links take you to the public, informational versions of the dynamic LEED Online forms for each NC-2009 IEQ credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.

Version 4 forms (newest):

Version 3 forms:

These links are posted by LEEDuser with USGBC's permission. USGBC has certain usage restrictions for these forms; for more information, visit LEED Online and click "Sample Forms Download."

Design Submittal

PencilDocumentation for this credit can be part of a Design Phase submittal.

508 Comments

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Jay Wierzbicki Energy Modeling Ecovert Sustainability Consultants
May 02 2013
Guest

LEED NC-2009 IEQc8.1: How to Average Multiple Tvis Values

I am trying to calculate the resultant TvisVisible light transmittance (VLT) (Tvis) is the ratio of total transmitted light to total incident light (i.e., the amount of visible spectrum, 380–780 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. value of glazing when the overall value is not provided. The manufacturer has provided specification sheets that show the window pane has a Tvis of 70% but also has a Security Window Film Application that has a Tvis of 86%.
I am currently using the formula: VLT1 x VLT2 = VLT3. The resultant Tvis value is then: 70 x 0.86 = 60.2%.
Is this the correct procedure to calculate the average of two Transmittance Values or for Daylight Calculation purposes is there another method that is stipulated by LEED 2009 to determine the resultant Tvis value.

Thanks in advance for your time and comments

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Jill Dalglish, PE Founder & Senior Engineer, Dalglish Daylighting May 08 2013 LEEDuser Expert 2855 Thumbs Up

I believe your math is correct.

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Devon Bertram Sustainability Manager, YR&G May 08 2013 LEEDuser Member 2937 Thumbs Up

Hi Jay, Generally speaking, your calculation method will result in a reasonably close VLT value. However, you may need to use NFRC values. You may want to look into the software program Optics from the Lawrence Berkeley National Laboratory, which allows you to build up glazing assemblies from an extensive glazing database, and derive a VLT for your specific product.

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Adrianna Schneider AEC Solutions Engineer Advanced Solutions, Inc.
Apr 29 2013
LEEDuser Member

Compliance Factor Over 0.18

The document sample I have states that the compliance factor is calculated by WindowArea/FloorArea * VLT
And then checking if it is between 0.15 and 0.18.

When it is less than .015, then the amount of compliant area is calculated, what about if its >0.18?

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Todd Reed Daylight Designer, 7group Apr 29 2013 LEEDuser Expert 3569 Thumbs Up

The only area that is compliant is the one that falls between 0.15 and 0.18. Anything below 0.15 is not compliant and anything above 0.18 is not compliant.

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Jill Dalglish, PE Founder & Senior Engineer, Dalglish Daylighting Apr 29 2013 LEEDuser Expert 2855 Thumbs Up

If it is less than 0.150, you can make it come out to 0.150 by adjusting your floor area. See the formula I posted on this site to Gabriela on Dec 14, 2012.

There is no "cure" for if you are over 0.180. In effect, it is one indication that you might be over-daylighting your space. You should take it as cue for redesign. Redesign would involve one or more of the following: recalculating using daylight simulation, lowering your VLT, and/or reducing your window size.

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Nena Elise
Apr 26 2013
LEEDuser Member
1846 Thumbs Up

Multipurpose Space in Basement Regularly Occupied?

Thank you Todd for answering my previous question- Now I have another one.

I am working on a fraternity building that has a large basement multipurpose space devoted to chapter activities, special events etc.

I looked through the IEQ Space Matrix and the closest space that I could find was student activity room which was marked as regularly occupied. However, it seems that since this space is in the basement and will probably only be used at most a few time a week- it could be considered not regularly occupied. Please advise-

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Todd Reed Daylight Designer, 7group Apr 26 2013 LEEDuser Expert 3569 Thumbs Up

I kind of laughed to myself when i first read "the basement space in a fraternity house" and I just began reminiscing about how that space was used.

Looking at the most recent regularly occupied space matrix, April 2103, this space could be considered a lounge, student activity room, or a living space. All these spaces are considered regularly occupied and should be included. Trying to justify it as not being regularly occupied based on a statement of being used a few times a week is not sufficient enough for exclusion.

If you can show that the space is not used for at least 1 hr daily by someone for some form of activity, then maybe. But if the space is left open all the time to be used by the members, for other uses outside of fraternity house business along with normal activities, then it needs to be included as regularly occupied.

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Sara Rosenthal
Apr 25 2013
LEEDuser Member

Zone floor area for Prescriptive Method

How do I measure the zone floor area for the Prescriptive Method? I'm getting thrown off by the footnote on the calculator which reads: "The zone size can be reduced as needed to increase the window to floor area ratioFloor Area Ratio (FAR) is the measure of the density of non-residential land use. It is the total non-residential building floor area divided by the total buildable land area available for non-residential uses.  For example, on a site with 10,000 square feet of buildable land area, an FAR of 1.0 would be 10,000 square feet of built building floor area.  On the same site, an FAR of 1.5 would be 15,000 square feet of built floor area; an FAR of 2.0 would be 20,000 built square feet and an FAR of 0.5 would be 5,000 built square feet.."

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Todd Reed Daylight Designer, 7group Apr 26 2013 LEEDuser Expert 3569 Thumbs Up

What that means is if you WFRxVLT is over over 0,18, you can reduce the size of your daylighting zone till it falls in between 0.15 and 0.18. Many times if you follow the method of establishing the daylighting zone, the entire area will not be compliant, which hurts you in earning the credit, by allowing you to reduce the zone area, you can then have at least some compliant area helping you in achieving the credit.

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Jill Dalglish, PE Founder & Senior Engineer, Dalglish Daylighting Apr 26 2013 LEEDuser Expert 2855 Thumbs Up

In my understanding, you can only adjust the size of your zone if it is UNDER 0.150, not if it is over 0.180. See the formula I posted on this site to Gabriela on Dec 14, 2012.

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Todd Reed Daylight Designer, 7group Apr 26 2013 LEEDuser Expert 3569 Thumbs Up

Jill is correct, I have had only two cups of coffee this morning.

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Lee Koepke Pre-Construction Manager RA-LIN and Associates, Inc.
Apr 25 2013
LEEDuser Member

Passages & Halls - Measurement

Good Afternoon.
We are pursuing the Measurement Option for Daylighting. My question is regarding whether "passages" are considered Normally Occupied. The general layout is an Open Office with workstations on the outside perimeter and management offices in the center. The "passage" i am questioning is the 5 foot stretch between the offices and the beginning rows of the workstations. Does that need to be counted as a Normally Occupied Space?
Any advice is greatly appreciated.

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Todd Reed Daylight Designer, 7group Apr 26 2013 LEEDuser Expert 3569 Thumbs Up

You could exclude that area but not the circulation areas between the workstations. Ensure that this is included in your narrative and highlight the circulation spaces on your floor plan.

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Lee Koepke Pre-Construction Manager, RA-LIN and Associates, Inc. Apr 26 2013 LEEDuser Member

Thanks Todd. That helps me alot.

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Nena Elise
Apr 16 2013
LEEDuser Member
1846 Thumbs Up

Automatic Shades in the Option 2: Prescriptive Method

The credit language for c8.1 is states:

"However, designs that incorporate view-preserving automated shades for glare control may demonstrate compliance for only the minimum 0.150 value"

I'm I correct in interpreting this to mean that spaces with a VLT X WFRWindow-to-floor ratio (WFR) is the total area of the window (measured vertically from 30 inches above the finished floor to the top of the glass, multiplied by the width of the glass) divided by the floor area. above 0.18 can be counted as daylit in the prescriptive method if they have automatic shades?

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Todd Reed Daylight Designer, 7group Apr 17 2013 LEEDuser Expert 3569 Thumbs Up

Nena, you are correct. As long as your VLTxWFR is above 0.15 and you have automatic shades, that area is compliant.

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Olivier Brouard Sustainable Energy Engineer
Apr 16 2013
Guest

Interior blinds under LEED 2009 NC

Hi Everyone,

I have seen two answers so far, so I will ask again, sorry.

Are interiors blinds a valid option under LEED 2009 NC to reduce the glaring issues when running a daylight simulation with areas over 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. on the grid analysis ?

If yes, how would you model - integrate it ?

Thank you.
Best,

Olivier

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Sara Heppe Senior Sustainable Designer, Clark Nexsen Apr 16 2013 LEEDuser Member 191 Thumbs Up

If the blinds adjust automatically to varying daylight conditions then they may count towards the credit. To simulate this condition you would run your simulation without any shading treatments applied to the windows. LEED allows you to count all of your square footage above the allowable daylighting limit towards your total, in spaces where your automatic shading devices exist.

If the blinds have to be adjusted manually then they do not count as a shading device.

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Todd Reed Daylight Designer, 7group Apr 16 2013 LEEDuser Expert 3569 Thumbs Up

No, blinds cannot be used in this version of LEED. Automatic shades allows you to only meet the minimum 10fc. The reason being is that in single point in time calculations, blinds are not used dynamically, they are either up or down. In the next version of LEED, sDA will be allowed which incorporates shades. However, you still have to run an ASE, which is without shades. Basically, you have to provide a design which meet the levels without relying on the occupants to operate the blinds.

You could incorporate exterior shading devices or interior lightshelves. Have you modeled exterior element, adjacent buildings, terrain, and even vegetation in your model? These elements can help with the low sun angles at 9am and 3pm.

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Olivier Brouard Sustainable Energy Engineer Apr 16 2013 Guest

Hi Everyone,

Thank you for your quick feedback and expertise.

I have indeed modeled everything except the vegetation. Working on a renovation project, I can't make any change on the outside boundaries of the building. The windows are recessed and the light shelf didn't bring a nice benefit to the indoor environment. It might help to shade the glaring area over 500fc on the analysis grid though.

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Eddy Santosa Sustainable Design Coordinator, HMC Architects Apr 16 2013 LEEDuser Expert 2202 Thumbs Up

Olivier, Just my 2 cents, I suggest you can investigate annual pattern. If the direct light keep penetrating directly to the room. The exploring other glazing options and additional fixed shading either inside or outside will be beneficial to your project not only for LEED purpose.

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VICTOR MORENO TECHNICAL DIRECTOR ISOLANA AHORRO ENERGÉTICO SL
Mar 28 2013
Guest
16 Thumbs Up

Simulation tool

Hi, I make a daylight simulation with Design Builder, that provides results for IEQ 8.1 v3.

Can i use this results to justify sample IEQ CREDIT 8.1: DAYLIGHT AND VIEWS - DAYLIGHT v4.0?

Thanks

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Todd Reed Daylight Designer, 7group Mar 28 2013 LEEDuser Expert 3569 Thumbs Up

Yes you can. Provide the simulation results for both 9am and 3pm along with a completed Supplemental Daylight and Views Calculator with each regularly occupied space listed separately and you should not have a problem. Just submitting their built in report would cause some issues with the reviewer if things are not documented clearly.

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Jill Dalglish, PE Founder & Senior Engineer, Dalglish Daylighting Mar 28 2013 LEEDuser Expert 2855 Thumbs Up

Are you working on a beta v4 project?

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VICTOR MORENO TECHNICAL DIRECTOR , ISOLANA AHORRO ENERGÉTICO SL Mar 28 2013 Guest 16 Thumbs Up

Thank you Tood.

Jill, Version 4 is the form version of the credit.

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Jill Dalglish, PE Founder & Senior Engineer, Dalglish Daylighting Mar 28 2013 LEEDuser Expert 2855 Thumbs Up

So it is a LEED 2009 project? Can you provide a link?

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VICTOR MORENO TECHNICAL DIRECTOR , ISOLANA AHORRO ENERGÉTICO SL Mar 29 2013 Guest 16 Thumbs Up

Hello Jill, what link do you like i provide?

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Marzia Sedino
Mar 22 2013
Guest

Modeling Context

Hi,

For credit compliance, under OPTION 1 - Simulation, is it required to model the building context (e.g. neighboring buildings/obstructions)? I have not been able to find anywhere references to this matter.

Many thanks

Marzia

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Todd Reed Daylight Designer, 7group Mar 27 2013 LEEDuser Expert 3569 Thumbs Up

It is not required that you do and you do not have to show that you have when submitting the credit. However, it is recommended in the Reference Guide.

Why wouldn't you include adjacent buildings, structures, topography, and even highly dense vegetation in your simulations? If you are just using the simulation method to document the credit and nothing more, then its your option to include it or not. However, if you are doing simulations in schematic and DD, like you should to help make design decisions and meet your daylighting goals, then those adjacent elements must be included.

You may find that without including the surrounding elements that you will not earn the credit because of direct solar penetration resulting in areas well above 500fc. However, adjacent structures, topography, and even representing vegetation will reduce this issue and will provide you with more realistic results to help you make better design decisions.

"I have never seen a building that sits in a flat plane of white and is surrounded by nothing"

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Marzia Sedino Mar 27 2013 Guest

Thank you Todd. It makes sense.
I was thinking that one reason for not modeling the conext is that it can (and in my case is likely to) change over time.

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E H Sustainability Architect
Feb 26 2013
LEEDuser Member
812 Thumbs Up

glare control devices on skylights?

Does anyboday know if glare control devices need to be provided on skylights?

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Jill Dalglish, PE Founder & Senior Engineer, Dalglish Daylighting Feb 26 2013 LEEDuser Expert 2855 Thumbs Up

In a word, Yes. In many words...The prescriptive options designates the amount of diffusion the skylights must have. This diffusion indirectly controls glare. The simulation and measurement options restrict the amount of light allowed onto the measurement plane. This also indirectly mandates glare control.

Beyond meeting LEED requirements, it is recommended that clear skylights or clear roof glazing of any sort should only be used in areas where direct glare can be tolerated, for example, transition or break room spaces.

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Todd Reed Daylight Designer, 7group Feb 26 2013 LEEDuser Expert 3569 Thumbs Up

The Reference Guide only states every window, so is a skylight a window?

As regards to LEED i have yet to read anywhere where skylights were required to have a glare control device. Typically, a skylight would not be in ones cones of vision, and as long as they were diffuse, can you label it a window. If they were north facing and or clear i would ensure that there was no potential for direct solar or glare.

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Eddy Santosa Sustainable Design Coordinator, HMC Architects Feb 26 2013 LEEDuser Expert 2202 Thumbs Up

In the spreadsheet, they said the glare is optional if the simulation shows illuminance within the range. I am not sure whether I have the latest spreadsheet.

Outside of LEED, i think it is necessary to provide glare control if the direct sun from the skylight falls on task area. However, if it is diffuse material and doesn't cause high contrast, I don't think it is necessary.

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Todd Reed Daylight Designer, 7group Feb 27 2013 LEEDuser Expert 3569 Thumbs Up

Eddy,
the spreadsheet does state that, but it is in contradictory to the Reference Guide. I have not yet got any clarification to this issue that has been around for awhile.

Here is the other dilemma, would a space need glare control if it one of it walls were say of Kalwall?

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Eddy Santosa Sustainable Design Coordinator, HMC Architects Feb 27 2013 LEEDuser Expert 2202 Thumbs Up

Todd,
In my personal opinion, Kalwall should qualify without blind. It has diffuse property and it won't cause any high contrast. The material of blind sometimes has even higher VLT than Kalwall. I think it will be similar case with solatube. I don't think both kalwall and solatube needs glare control.
I saw this provision : Provide glare control devices to avoid high-contrast situations that could impede visual tasks.
The worst case scenario is that we need to provide glare study to the reviewer as a back up information.

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Todd Reed Daylight Designer, 7group Feb 27 2013 LEEDuser Expert 3569 Thumbs Up

Eddy, I agree that Kalwall doesn;t need glare control devices, nor would solar tubes at this point in LEED. Depending on the haze factor, location, orientation, and activity of the space, there may be a time where something may be needed.

I believe a glare/contrast study would work if questioned, but what would you include in the study to the reviewer? I believe many reviewers may not even be able to readily define glare or what entails in a good glare/contrast study.

Well I'm about to find out real soon if these items will be questioned or not. We have a project that has north facing skylights that are clear, south facing skylights that are translucent, and Kalwall on the east and west facades. Sims show good daylighting, contrast ratios are within 1:4 in the worst case scenarios, and blinds are used consistently. Daylighting design was based on Daylight Autonomy and not LEED requirements, but it easily meets the LEED requirements for this version.

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Eddy Santosa Sustainable Design Coordinator, HMC Architects Feb 27 2013 LEEDuser Expert 2202 Thumbs Up

I included a luminance study, but I agree with you if they may not even look at that. The daylight review is not as detail as EAc1 review. I never received technical question from the reviewer in daylight. They mostly asked about the regularly occupied, etc.
I bet your project should be OK. 1:4 luminance contrast is very good. If you don't mind sharing after receiving the reviewer comment, it will be great.

The reference even includes fritted glass as their glare strategy. In most cases, I believe the fritted will create more glare than the diffuse glass.

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kate dixon
Feb 16 2013
Guest

too much light?

I calculated the floor area in rooms that had less than .15 that would contribute. however, many spaces have over .18 (too much light). My overall calculation for the building is currently 54% daylighting. How can I use some of the lighting from the spaces with calculations over .18? There are horizontal louver blinds on all exterior windows, so they are user adjusted, but I am wondering how to calculate these spaces. Please help!

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Todd Reed Daylight Designer, 7group Feb 18 2013 LEEDuser Expert 3569 Thumbs Up

Kate,
First off, the prescriptive method does not indicate you have too much or too little daylight. You can say that a space over 0.18 has the potential to be over daylit and a space with 0.15 or less may possibly not have the potential to have enough.

You can reduce the the area of your daylight zone until it is compliant. This will usually work for the spaces below 0.15. You cannot increase the size of your daylight zone.

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Eddy Santosa Sustainable Design Coordinator, HMC Architects Feb 18 2013 LEEDuser Expert 2202 Thumbs Up

Kate, you may need to use the simulation method if you concern with the daylight inside.

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Emmanuel Pauwels Owner Green Living Projects s.l.
Feb 12 2013
LEEDuser Member
962 Thumbs Up

industrial project roof

We are trying to use the prescriptive method for an industrial Project which is planning to incorpórate a "shed" type roof which has horizontal glass on on side . Sincé it is in the roof, it is a skylight, but since the Windows are vertical they are tecnically to be considered Windows. Can we use the prescriptive model for this?

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Todd Reed Daylight Designer, 7group Feb 12 2013 LEEDuser Expert 3569 Thumbs Up

Emmanuel, are these clerestory windowsPronounced and sometimes spelled "clear-story," these are vertical, or close-to-vertical, windows high in the wall of a building that bring daylight deeply into the building and, if operable, can help ventilate the space.? Just trying to picture what this scenario is. Too bad you can't upload a sketch on here to show what is going on.

Without seeing what is going on, i would say that you can;t use the prescriptive method to document clerestory windows that are located within the roof areaRoof area is the area of the uppermost surface of the building which covers enclosed Gross Floor Area, as measured when projected onto a flat, horizontal surface (i.e. as seen in Roof Plan view). ‘Roofs’, or portions of roofs, covering unenclosed areas (e.g. roofs over porches and open covered parking structures) are not included in the areas used to evaluate compliance with SSc7.2, though they may be applicable to SSc7.1.. The reason being is that the prescriptive method is very limited and its only really meant for prescribed scenarios. The methodology is based on how much of the sky dome is accessible through an opening. That is why you use 2H or the 63 degree angle to establish the depth of your zone, it is also why with skylight you use 35 degree angles. Its all about access to the sky. Clerestories are great daylighting strategies which, depending on their orientation, can provide some great reflective and indirect light into a space.

To say that your daylight zone is the area that is defined by drawing a line straight down from the glazing surface and then the depth would be what? If the clerestories are really high, you couldn;t use 2H because leading edge of the zone technically has no access to the sky dome and the prescriptive method can;t be used for reflective strategies. Drawing a angle from the head of the clerestory window using the 63 degree may result in a realistic daylight zone, but if the windows are really high, the angle would create an unrealistic zone.

You can;t really use any of the steps in determining the daylight zone from skylights because the clerestory glazing is vertical, and not horizontal.

Without being able to establish a zone, you can;t demonstrate the ratio. Without the ratio, you can;t document the method.

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Emmanuel Pauwels Owner, Green Living Projects s.l. Feb 12 2013 LEEDuser Member 962 Thumbs Up

Todd,
Thanks for your reply. The Windows are indeed clerestory WindowsPronounced and sometimes spelled "clear-story," these are vertical, or close-to-vertical, windows high in the wall of a building that bring daylight deeply into the building and, if operable, can help ventilate the space. on the roof. The height of the área is 10 meters which is high. One part of the roof has curbed skylights. I guess we can count those, right? Other part of the roof are those clerestory Windows which as you explained can not be validated with the prescreptive method. A 35º angle from the opening in the roof would cover a very large zone, so I do not think that is realistic.

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Todd Reed Daylight Designer, 7group Feb 12 2013 LEEDuser Expert 3569 Thumbs Up

Your curbed skylights can be used in the prescriptive method. If this is already built, then just use measurements, otherwise simulation is the best way to go. If your just trying to earn the daylight credit without wanting to know performance then you could use the prescriptive method, minus the clerestories.

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Emmanuel Pauwels Owner, Green Living Projects s.l. Feb 12 2013 LEEDuser Member 962 Thumbs Up

Thanks Todd. Even when the height is 10m can I use the curbed skylights in the prescriptive method. Is there no height limit?

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Todd Reed Daylight Designer, 7group Feb 12 2013 LEEDuser Expert 3569 Thumbs Up

There is no height limit, but there are the other requirements that must be met as noted in the Reference Guide.

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Brady Hartmann
Jan 09 2013
Guest
5 Thumbs Up

IEQc8.1 Day Lighting exempt spaces

I am trying to determine if a specific room can be excluded from the day lighting calculation. For the measurement path, it states that exceptions for areas where tasks would be hindered by daylight will be considered on their merit.
The room in question is within a new 12,300 sf office building located in Oklahoma. The 1100 sf room, with an open office layout is located at one corner of the building. It will also serve as a safe room for the building occupants, so the floor, walls and ceiling have been hardened to resist the forces of a tornado per FEMA 361. For safety reasons, there are no windows into this space.
Can this room be excluded from the day light calculation?

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Todd Reed Daylight Designer, 7group Jan 10 2013 LEEDuser Expert 3569 Thumbs Up

It could be if you put a good narrative together explaining why you have to have a safe room and exactly why it is designed the way it is. If you just say it is excluded because of FEMA 361, i believe the reviewer would question that since in FEMA 361, windows are allowed as long as they meet a certain criteria and are protected accordingly. It's a really big document that not alot people know about and probably not alot of reviewers do either.

There are many other questions with this that you'll need to clarify, such as why is a regularly occupied space deemed a shelter; also, why can;t a separate space in the basement be the shelter, why does this building have to have a shelter, why isn;t it located in the core of the building, etc. etc. Is this building required to have a shelter and what authority is saying that it has too.

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Brady Hartmann Jan 10 2013 Guest 5 Thumbs Up

Todd,
Thanks for your comments.
This is a project for the U.S. Army, and the Hardened Room per FEMA 361 was a project requirement. In addition, a basement was not preffered by the governement because of the site's agressively expansive soil and the associated costs. FEMA does allow windows but it also states that "Testing indicates that glass windows in any configuration are undesirable for use in tornado safe rooms" especially in the highest hazard region where our building is located, and it recommends that windows not be included.
For safety reasons we were working to reduce the number of openings into the space.
The remaining spaces do very well with day lighting, and there are FEMA doors that open into the room from adjacent offices that if left in the open position, offer borrowed light to the space.
We will provide a complete narrative. I am just trying to get a sense of what is reasonable.
Thanks for your input!

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Todd Reed Daylight Designer, 7group Jan 10 2013 LEEDuser Expert 3569 Thumbs Up

You wont be able to use any borrowed light that comes through an open door, doors must be closed and borrowed light must come through any door glazing or side light.

Based on your further response, I'd say that this space is going to have to be included. Reason being is that the shelter could have been in the basement, but because of finances was not, financial issues do not take precedent over LEED requirements. The other reason is that you are using an office space as the shelter and why would you place people in a work space without any windows, especially in just an office. If it were a clean room or some other critical task sure, but an open office does not make sense. It actually goes against the intent of the credit. Yes , the shelter was a requirement, but could another space been used or the the building been designed so that an open office space did not have to be used? Sometimes, a project just can;t earn a credit.

You can still make your argument but i would suggest that if you truly need this space to be excluded to earn the credit, that you approach GBCI with your narrative prior to submitting this. This would be done in the credit LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org..

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Brady Hartmann Jan 10 2013 Guest 5 Thumbs Up

Todd,
Agreed. Sometimes a project just can't earn a credit.
We may choose to pursue this and present our argument, or we may not.
I was just trying to figure the liklihood, given the FEMA 361 aspect.
I will put that point in the "?" column.
Thanks!

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Jill Dalglish, PE Founder & Senior Engineer, Dalglish Daylighting Jan 10 2013 LEEDuser Expert 2855 Thumbs Up

I tend to agree with Todd here. I think that if you are using this space primarily as an open office, it is very unlikely that using the FEMA requirements will exempt it. Primarily because of the dual use. The FEMA requirements don't indicate that you must have an open office space in a safe room, therefore you have the option of separating the uses and providing daylight to your open office occupants. Great question! Now, are you sure you don't want to give those occupants some daylight?

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Brady Hartmann Jan 10 2013 Guest 5 Thumbs Up

Uff..
Well, the building is nearly complete so we are looking at the Measuremnt Path for this credit. Several design solutions were offered early on in the design process to provide daylight/views to this space, but none fit the bill. Due to secure access and use, this was the only adequately sized space available in the building for the FEMA requirement.
We understand that the FEMA doors can't be held open for the measurement (so this room will achieve 0 sf regularly occupied daylit area) I just mentioned it because that is what the user will do, and so things will lighten up a bit for that space.
Thanks for your input!

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Gaston Viau
Jan 07 2013
Guest
43 Thumbs Up

Design Submittal

This credit cannot be submitted on the deign phase if we choose option 3 (measurement) right?

Thanks in advance for your time.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Jan 07 2013 LEEDuser Moderator

Correct.

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Dan Bielenin William Rawn Associates
Dec 17 2012
LEEDuser Member
12 Thumbs Up

Accounting for Future Fit-Out Retail Spaces in NC 2009

I am trying to determine how to account for core and shell retail spaces located on the ground floor of a project pursuing certification under NC 2009. The retail spaces are to be fit out entirely by the future tenants, who have not yet been determined. Is there a method for calculating the daylight and views for a space prior to fit-out? Should I run the calculation on an empty floor plate since we don’t have knowledge of who the future tenants will be? Should I simply make assumptions on how the spaces may eventually be organized?

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Jill Dalglish, PE Founder & Senior Engineer, Dalglish Daylighting Dec 17 2012 LEEDuser Expert 2855 Thumbs Up

Hello Dan,
If you are certifying a Core and Shell space, you should be using LEED Core and Shell, not LEED NC.

Also, you may get more help with your questions on the LEEDuser Core and Shell forum.

But, to answer the question, you would plan out a predicted layout for the tenants. I believe you would also need to have the owner put a tenant agreement in place that requires the retail spaces to abide by certain rules in order to get the C&S credit. For example, that they will not locate any walls parallel to the windows withing the daylighting zone. But, I'm not sure on that last part. Perhaps others here or in the C&S forum know more certainly.

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Dan Bielenin William Rawn Associates Dec 17 2012 LEEDuser Member 12 Thumbs Up

Thanks, Jill. The project is a multi-family apartment complex with a retail component along the ground floor. We are pursuing certification under LEED NC 2009; however, I am assuming the retail component would need to abide by any guidelines set forth in LEED CS.

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Todd Reed Daylight Designer, 7group Dec 17 2012 LEEDuser Expert 3569 Thumbs Up

Jill, Dan has two CS spaces within a NC project, it is acceptable to have these types of spaces within a NC project if it does not succeed a certain percentage of the total floor space.

Dan, first off the owner will need a tenant lease agreement that states the building has been designed to meet the LEED requirements of credit EQc8.1. Therefore your fit out must do the following....... There is a good section on LEED Users that outlines what a tenant lease agreement should have in it. Now, if you do not have tenants already signed you need to submit a copy of the tenant lease agreement that the tenants will be singing.

To document the credit, you could propose a tenant layout, which could be one that is used in the tenant lease agreement. This is then used to document both credits. You could also document the empty space, but depending on the depth of the space, you may actually hurt yourself. Typical retail will have their storage towards the core, so that area is not considered regularly occupied and does not hurt the calculations. But with an empty space it is considered regularly occupied, unless your design provides daylight into the depths, then it does not hurt you. In your tenant lease agreement you could tailor it based on your daylight potential and the actual daylight sim results. Lets say your sims show that the space will meet a targeted illuminance level in a certain percentage of the space. Your agreement could dictate where the tenants can and cannot enclose or require that a certain percentage of square footage towards the window wall must be open.

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Todd Reed Daylight Designer, 7group Dec 17 2012 LEEDuser Expert 3569 Thumbs Up

All spaces within these LEED-NC projects must be considered for compliance.
As noted in several LEED Interpretations, such as LEED Interpretation 3900, projects containing unfinished spaces must provide Tenant Design and Construction Guidelines to ensure that future fit-outs can also meet LEED prerequisites and requirements for the credits pursued by this LEED project.
Alternatively, for unfinished spaces intended to be fit-out by the Owner at a later date, a signed statement from the Owner indicating that all future fit-outs executed to complete these unfinished space(s) will be completed in accordance with the requirements of all prerequisites and credits achieved by this LEED project will be accepted.

Please provide a narrative that confirms all completed aspects of the project relevant to any prerequisites/credits have been included in the submittal documentation and calculations. Any aspects of these unfinished spaces that have not yet been installed must be excluded from the calculations for these prerequisites/credits. Occupancy values must be determined for all spaces in the building, including both finished and unfinished spaces, and applied to any credits that use occupancy values to calculate compliance. If the future occupant count for unfinished space(s) is not yet known, Appendix 1 from the LEED-CS v2.0 Reference Guide should be used to establish the occupant counts for unfinished spaces. Any aspects of these unfinished spaces that have not yet been installed should be excluded from the calculations, except in calculations for WEc2, WEc3, EAc1 and any attempted credits that are dependent upon the results of that credit.
Anticipated, but as yet uninstalled, water- and energy-consuming fixtures regulated by WEc3 and EAc1 must be estimated in the Design (i.e. Proposed) case as being equivalent to the Baseline case for the intended use of the space.

For any unfinished space(s) intended for future fit-out by the LEED project Owner, provide a signed statement from the Owner that any future fit-out required to complete the space will be executed in accordance with the requirements of this prerequisites/credits.

For any incomplete space(s) intended for fit-out by one or more tenants (i.e. entities other than the LEED project Owner), provide Tenant Design and Construction Guidelines with language to ensure that future tenants can comply with the requirements of these prerequisites/credits. Tenant Design and Construction Guidelines must include a description of the sustainable design and construction features incorporated in the project and information that enables a tenant to coordinate their space design and construction with the rest of the building systems, as well as information regarding how features of the base building can contribute to certification of the tenant
space(s) under the LEED-CI rating system. Refer to the full description of these guidelines in SSc9: Tenant Design and Construction Guidelines of the LEED-CS rating system, for more information.

Projects can upload one copy of the appropriate Owner's Letter of Commitment and/or Tenant Design and Construction Guidelines to the Documents tab in LEED Online and simply reference them in the final review submittal narrative for each applicable credit/prerequisite. Please note that neither the Owner's Letter of Commitment nor the Tenant Design and Construction Guidelines may be used to claim credit for uninstalled aspects of the unfinished spaces. This guidance applies to all of your related LEED-NC projects with unfinished spaces.

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Gabriela Almquist
Dec 03 2012
Guest
6 Thumbs Up

Password and Zone Floor Area questions

Hi, I'm trying to add a regularly occupied space (row) in the excel spreadsheet and it gives me an error message saying I do not have permission. Is there a way to add more spaces if I don't have a password?

Also, in the prescriptive calc, what exactly is the difference between "Floor Area" and "Zone Floor Area"? Are they always the same number?

Lastly, note #5 in the spreadsheet has you calculate le lesser of 70% ceiling height, 1/2 distance to edge of nearest skylight, etc. My question is, how do you add that to the floor area (since floor area is sqft and the celing height/distance is in ft)?

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Todd Reed Daylight Designer, 7group Dec 04 2012 LEEDuser Expert 3569 Thumbs Up

Have you tried saving the spreadsheet to your desktop as another name?

Floor area is the total space, or regularly occupied space of the room and Zone floor area is the daylighting zone established for that space or series of space.

As far as note 5, what that is, is the area under the skylights (actual square footage) that is calculated by whichever one of the following three options produces the lowest amount of square footage. 1. the zonal floor area may be the ceiling height x 0.70%. 2. 1/2 the distance between the skylights. If you only have one, then you can;t use this method. 3. Is done just as noted.

You never add in the floor area, its the floor area determined by the above methodology.

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Gabriela Almquist Dec 04 2012 Guest 6 Thumbs Up

Thanks Todd. The excel sheet works now, and I can add spaces.

I'm still confused about Floor Area and Zone Floor Area. This is how I'm calculating it: If my room has no windows, then its ZFA is zero. If 100% of the Floor Area is regularly occupied, then the Floor Area and Zone Floor Area have the same square footage. Is this corret?

I have a 3203sf room with 171sf of window area (which seems like a lot to me) and the TvisVisible light transmittance (VLT) (Tvis) is the ratio of total transmitted light to total incident light (i.e., the amount of visible spectrum, 380–780 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 0.397. According to the spreadsheet, the VLTxWFR is supposed to be between 0.15 and 0.18, but I get 0.021 in this particular room. The only thing I can think of that can be wrong is the ZFA, since I used 3203sf thinking that 100% of the room is regularly occupied. Any ideas?

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Todd Reed Daylight Designer, 7group Dec 04 2012 LEEDuser Expert 3569 Thumbs Up

If your space is regular occupied and has no windows, then your floor area is the total regular occupied area of the space and your zonal area is 0. Your zonal area is the area of the daylighting zone calculated by either twice the window height in depth or using the 60 degree angle from the head of window, times, the length . So if no window no zone, but the regular occupied space is still included in the calculations.

171 sf of window in a room that size is not much, that is only 5% window to floor ratio general rule of thumb, depending on orientation, is at least 10%. So the spreadsheet is right, you have a little bit of window, with a very low VLT, in a big space, so it is not a very good daylighting scenario.

How are calculating the depth of your daylighting zone?

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Gabriela Almquist Dec 04 2012 Guest 6 Thumbs Up

Sorry, I miscalculated. The window area is actually 360sf in that room but I'm still getting 0.045 VLTxWFR. Should we probably look at getting a different window with a higher TvisVisible light transmittance (VLT) (Tvis) is the ratio of total transmitted light to total incident light (i.e., the amount of visible spectrum, 380–780 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.?

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Todd Reed Daylight Designer, 7group Dec 04 2012 LEEDuser Expert 3569 Thumbs Up

What is the length and width of the room and what is the window head height?

At this point are you only looking at changing the VLT soley based on earning the daylight credit via the prescriptive path? If you are, then i would say that you should not use the prescriptive calculations to design the daylighting performance of a building. It cannot be used to do it because it is only a formula that tells you if your inputs meet a certain parameter. It cannot tell you performance levels, it is not climate or orientated based. I just don;t recommend this option.

Gabriela, to answer the question about changing the VLT would require alot more information of the space, climate, orientation, target illuminance levels, etc, etc. I would never say change it based on the prescriptive path.

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Gabriela Almquist Dec 04 2012 Guest 6 Thumbs Up

The room is roughly 52'-0" x 58'-0" and the window head height is 10'-0". We have many other rooms, but this is just one example.

We are trying to get the daylighting credit via the prescriptive path since we don't have a simulation model. Are you recommending we do it via the measurement calc? We don't think we can get the Views credit, so we aren't even trying for that one.

Thanks again!

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Todd Reed Daylight Designer, 7group Dec 04 2012 LEEDuser Expert 3569 Thumbs Up

Ok, so your zonal area is the area that is the length of windows and the depth which is established by either twice the window head height, which would be 20 feet into the space, or based on a depth by using the 60 degree angle.(See Reference Guide)

What I am recommending is that you design the spaces/building based on set performance parameters and not based on earning points on a LEED scorecard. If you truly want to provide daylight to the occupants then design the space based on a set of performance parameters. Kind of like, "Form follows Function, or in this case "Form follows Performance". This will require at least simulation. It is also highly recommended that decisions made for daylighting are also coordinated with HVAC design. Does adding too much glazing and or a higher VLT increas the heat gain or does the introduction of daylightin reduce the lighting load. All parts work together, so they should be designed together.

Right now, if you just want to see if you earn the credit, perform the prescriptive calculations. If you get it you get it, if not, maybe try the measurement option when completed.

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