CS-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.

  • 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.

  • 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 Core and Shell Development

    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

    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.) 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; additionally, automatic photocell-based controls can help 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.

Software Tools

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.  

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.

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.

Technical Guides

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.

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.     

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.

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.

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.

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.

Design Submittal

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

57 Comments

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Petr Vogel Specialist Consultant EkoWATT CZ
Apr 13 2013
LEEDuser Member
34 Thumbs Up

Tenant Lease Agreement - Interior glare protection

Dear all,
when assuming interior blinds to allow glare control in tenant spaces. Does the condition of installing blinds have to be included in the Tenant Lease Agreement? Credit IEQc8.1 is not listed in Appendix 4 of the Reference Guide.
Thanks for any kind of help.

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Olivier Brouard Sustainable Energy Engineer
Mar 20 2013
Guest

LEED IEQ8.1: how to add simulation results for different floor ?

Hi !

Running daylighting analysis on a 4 stories building, assuming 3 floors have more than 75% of natural daylight between 10fc-500fc in regularly occupied space, whereas the last floor has less than 75%, then should I assume I don't pass the credit ?
how is the credit calculated when having multiple stories ?

Thank you !

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Todd Reed Daylight Designer, 7group Mar 21 2013 LEEDuser Expert 3569 Thumbs Up

Olivier,

Compliance is based on the total regular occupied square footage. So being over the 75% on three floors, that area being over 75% could make up the difference for the fourth floor.

To properly calculate the credit you need to complete the Supplemental Daylight and Views Calculator. Each space should have its own line and the compliant area should be noted for each based on the simulation results. The values will be automatically calculated.

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shashank jain Environmental Analyst BDSP Partnership
Sep 03 2012
Guest
61 Thumbs Up

Blinds for glare control - manual or automated

Seen some of the comments up there... But I wanted to ask if the blinds that are required as part of the glare control in IEQ 8.1 ... can they be simple manually controlled internal blinds... or only the automated ones are counted towards the credit compliance ?

Thanks

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

They can just be manually controlled blinds.

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Yelena Gipsov Architect, LEED AP VAAB Design
Jun 19 2012
Guest
88 Thumbs Up

New Calculation Spreadsheet

Hello!
I am working with the new Supplemental Daylight and Views Calculation Spreadsheet, prescriptive option. There is a column "Glare Control Type for spaces with 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. > 0.18". Does it mean that we don't need any glare control devices if VLT X WFR < 0.18? Appreciate any advice.

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Todd Reed Daylight Designer, 7group Jun 20 2012 LEEDuser Expert 3569 Thumbs Up

You must provide glare control devices for all spaces that are compliant. Only if you have incorporated automated shades are you allowed to meet the requirement with the 0.150 value.

It doesn't make any sense as to why that header is labeled that way because the requirement has always been that you must provide some type of glare control device. I never noticed that before. all the erratas and addendas state that you must provide glare control devices.

I'm going to go through some channels and see whats up with that header. I can see how someone filling it out could provide the wrong information causing for review issues.

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Lucie Sancova
May 31 2012
LEEDuser Member
55 Thumbs Up

Daylight simulation for office building

LEED reference guide said that in Option 1 compliance should be demonstrated through computer simulation of all regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building.. Is it necessary to perform the simulation for absolutely all the regularly occupied spaces in the building?

We are working with 7 floor office building that consists of 1 floor of restaurant and lobby and 6 floors of office spaces. The first floor of office floors has different floor area but the rest of the floors have almost the same floor area and shape. We don´t know the real tenant fit outs layout because the tenants are not already known. We have drawings of 2 floors of office floors with the sample tenant fit out layout from architects – one sample floor of separate enclosed office rooms and one floor of open offices.

Our building is very large, the simulation of all of the spaces would be very expensive and the results for all of the 5 floors of office spaces will be almost the same. Is it possible to perform the simulation only for example for our 1st, 2nd floor and one sample floor of both separate and open space offices to show compliance with this credit? Or is it possible to perform the simulation only for the worst cases of space with low daylight illuminance and if this space fulfils the requirements can we assume that the other spaces will fulfil the requirements too?

Thanks!

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Todd Reed Daylight Designer, 7group May 31 2012 LEEDuser Expert 3569 Thumbs Up

Lucie, you do not have to perform calculations for every floor that is the same. I would simulate the ground floor, the 1st floor of offices, and then a simulation of to show the results all the similar floors.

If three sims is too much of an expense, the worst case scenario approach could work if documented properly and if the reviewer understands daylight and simulations. If you do not document this approach clearly and the reviewer has to do a lot of comparison and extrapolation on their own, they could easily request the simulations. How much time and money for this approach versus just one more sim should be compared.

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Mathilda Jonsson Environmental Certification Engineer
Apr 13 2012
LEEDuser Member
448 Thumbs Up

Daylight calculations for office spaces with tenants

Hi all!
I'm working with at office building seeking LEED for CS certification. I have these big floor plans of 6383 divided by 3-4 tenants. In my earlier daylight calculations I didn't calculate with the tenant fit outs layout, I just took the whole floor plan areas and the window areas as CS is not taking into account for tenant fit outs. Of course I didn't meet the 75 %. Now I'm thinking that this doesn't say anything how the daylight is provided to the office spaces since it will be seperate office rooms for some tenants and open landscape for some. Do you think I can give it a try to take a few typical tenant fit out layouts to show compliance with this credit?

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Todd Reed Daylight Designer, 7group Apr 13 2012 LEEDuser Expert 3569 Thumbs Up

I would establish tenant guidelines that dictate appropriate layout designs based on the amount of daylight. Your initial analysis shows you the daylight levels. So based on this, i would establish areas that need to be open office and those that could be enclosed. I would also outline areas that would not be regularly occupied. I think that method has merit because of the use of daylight analysis to help guide the tenant guidelines. This way, no matter who the tenant is, they take advantage of the daylight available.

If anything, it is good practice to show potential tenants and the owner that the guidelines will help in energy reductions and provide a healthier working environment.

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Mathilda Jonsson Environmental Certification Engineer Apr 24 2012 LEEDuser Member 448 Thumbs Up

Thank you Todd for your reply.
The project is already drawing tenants outfits so I hoped that I just could take some of these for examples and show the daylight calculation, you don't think this would be a good idea? My other issue is that the building has first the structure with windows and outside that there is an additional glass facade. One requirement of IEQc8.1 is that the daylight must not go through more than one window, if I'm not misstaken. Is this credit out of reach beacuse of our double facade system?

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Todd Reed Daylight Designer, 7group Apr 24 2012 LEEDuser Expert 3569 Thumbs Up

You will not be able to use the prescriptive path because of the double facade. Simulations or measurements will be your only means to demonstrate credit compliance.

I don;t think that your methodology is a bad idea, but because of this being CS your going to have to show compliance without the fit out. I haven;t read any CIRs for CS to see if the methodology of establishing tenant guidelines to dictate how the floor area will be fit out because of daylight levels. I would be hard press to say that if you submitted this methodology that it would be earned because of the credit language.

You could send an inquiry to GBCI to see if this would be accepted but i'm think that it may not, even though it is commendable and is trying to meet the intent of the credit.

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Jill Dalglish, PE Founder & Senior Engineer, Dalglish Daylighting Apr 24 2012 LEEDuser Expert 2855 Thumbs Up

Mathilda and Todd, It was my understanding that we are supposed to create a sample tenant fit out in CS and do the calculations with those. I thought this was the same with the energy modeling credits. Maybe I'm thinking of v2.2? Todd, can you quote where you heard that it has to be done without the fit out? I am not certain either way, but it seems to make more sense to me to do a sample design. And if you already have some tenants I would think you could use their plans as sample plans.

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Todd Reed Daylight Designer, 7group Apr 24 2012 LEEDuser Expert 3569 Thumbs Up

In EQc 8.2 it requires that a tenant fit out be used in the views calculations. There is nothing in the 8.1 language, unless they added that in the erratta that i missed.

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Jill Dalglish, PE Founder & Senior Engineer, Dalglish Daylighting Apr 24 2012 LEEDuser Expert 2855 Thumbs Up

So there is nothing that you know of that says that it CAN'T be done with a sample tenant fit out? Just another example of credit language ambiguity and discontinuity between credits?

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Angela Saggin
Feb 06 2012
Guest
232 Thumbs Up

Option 2 - Prescriptive

Hi!
I'm trying to get IEQ C8.1 by the prescriptive option, but I'm having problems with the calculation of the window areas.

Its a residential building and the project contains plenty of balconies and not much windows. Could I consider the areas of the glass doors from the balconies? To calculate these areas, should I use the window head height minus 30 inches or the height of the balcony's sill? And the obstruction of the ceiling of the balcony, should I use the 63-degree angle from the vertical to modify the height?

Thanks!

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Todd Reed Daylight Designer, 7group Feb 06 2012 LEEDuser Expert 3569 Thumbs Up

Use the glass from the doors minus the 30 inches. There is nothing that i have read that has this situation that requires the height of the rail to be used instead of the typical height. You get really technical with that if the rail was solid and went the whole way around the balcony and argue that a rail higher than 30 is blocking daylight. If its not within a few feet i would just use the 30 inches.
Draw the 63 angle from the end of the balcony above. Reason being is that the angle in the prescriptive method is considering the floor space which has access to the sky dome.

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Angela Saggin Feb 07 2012 Guest 232 Thumbs Up

Thanks a lot, Todd!

One more question... should we consider the balcony as a regularly occupied space? It will have a barbecue grill and it's usually used as a space to hang out..

Thanks again!

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Todd Reed Daylight Designer, 7group Feb 07 2012 LEEDuser Expert 3569 Thumbs Up

The balcony is an outdoor space so it would not have to be considered in your regularly occupied space calculations.

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Sarah Sachs Buro Happold
Nov 02 2011
LEEDuser Member
148 Thumbs Up

Tenant Lease Agreement compliance path for glare control IEQc8.1

Has anyone used the Tenant Lease Agreement compliance path for glare control in LEED CS projects where the automated shades are being required by the developer but provided by the tenant?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Nov 14 2011 LEEDuser Moderator

Sarah, I could be wrong, but I think that since IEQc8.1 is not listed in CS Appendix 4, this approach could not contribute to this credit.

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Alexander Benning Project Manager ES EnviroSustain GmbH
Oct 07 2011
LEEDuser Member
180 Thumbs Up

No VLT available

Hello,
for our CS project we would like to implement option 2. The difficulty I have is that the building was constructed in the early 90ties and only little information on the existing parts is available. Unfortunately I have no proven VLT for the calculations. In addition windows literally run all around the house on every storey, but they all do have blinds on the outside, which can be operated individually.
Would it still be possible to achieve the ICQc 8.1 via option 2 or would we be forced to measure the whole building?
Thanks.

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David Posada Sustainability Manager, GBD Architects Oct 10 2011 LEEDuser Expert 11712 Thumbs Up

You will need a reliable source for the VLT value in order to use option 2. It might take some time, but if you can research any of the drawings, specifications, permits, payment receipts, or paperwork from the original construction that could help. If you can determine the manufacturer of the windows, they may have a record of the installation or product data from that time.

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Todd Reed Daylight Designer, 7group Oct 12 2011 LEEDuser Expert 3569 Thumbs Up

Use a good light meter. Take a reading on the inside of the window, about a foot away. Then immediately take a reading outside the window. Simple math will give you the VLT. It is not as scientific as the NFRC method, but it is close enough to get you what you need for the calcs.

Do not take readings of direct sun. Take readings at windows where there is just clear sky. Be careful of reflectances from surrounding objects and the glass itself. Turn off the interior lights.

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Alexander Benning Project Manager, ES EnviroSustain GmbH Oct 13 2011 LEEDuser Member 180 Thumbs Up

I did not know that that would be sufficient.
Thanks a lot!

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Todd Reed Daylight Designer, 7group Oct 14 2011 LEEDuser Expert 3569 Thumbs Up

The other option which is also acceptable for EAc 1 is to use table A8.2 in ASHRAE. This gives a VLT and other properties to use if it is unknown. Not the best properties, but it is a referenced standard and accepted method.

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Valerie Molinski Director of Sustainability, Vocon Feb 06 2012 LEEDuser Member 418 Thumbs Up

My project is in a high rise, built in the early 90's, so I cannot take a reading outside. I wonder what kind of success people have had using the default VLT's in the ASHRAE table.

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Anderson Benite
Jun 10 2011
LEEDuser Member
727 Thumbs Up

Glare control in CS projects

Hello,

We would like to clarify some questions regarding the credit EQc8.1 – Daylighting for buildings pursuing LEED 2009 Core&Shell certification in Brazil.

When it comes to Core&Shell buildings, we apply the Tenant Sales and Lease Agreement compliance path for any device that will not be installed in the building by the end of construction stage. EQc8.1 credit requests the use of glare control devices for all options and do not accept the Tenant Sales and Lease Agreement compliance path.

Glare control devices are usually considered by architectural design in Brazil including ceiling and fenestration projects. Even though glare control devices are not delivered by the contractor, they are always installed during interior fit-out by the tenant. Due to the daylight availability in tropical climates such as Brazil and their consequent frequently exacerbated discomfort and disability glare problems, tenants are naturally forced to install glare control devices as to provide minimum comfort conditions for the occupants.

According to this scenario above, we would like to know what would be a possible path to comply with credit requirements. Considering that is not possible to use, in this situation, the Tenant Sales and Lease Agreement, how can we proceed to get the credit compliance?

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Eddy Santosa Sustainable Design Coordinator, HMC Architects Sep 08 2011 LEEDuser Expert 2202 Thumbs Up

Hi Anderson,
In my opinion, the only possibility is to include the glare control as a part of architecture feature such fritted glazing or shading device.
Additionally, You may do your glare study if you have low transmittance value to prove that there is no glare in your building.

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diego prada Green Factory
May 05 2011
Guest
326 Thumbs Up

About Option 3: Measurement

Hello,

If one decides to use option 3 to show compliance with this credit, should the light measurements have to be done in a specific time of the day? This doesn't seems to be the case, but we want understand each option's specifications before deciding with one to use.

Thank you very much

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Todd Reed Daylight Designer, 7group Aug 26 2011 LEEDuser Expert 3569 Thumbs Up

There is no specific time. It is recommended that they are conducted as close to solar noon as possible and under clear skies.

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Omar Katanani
Feb 18 2011
LEEDuser Member
5313 Thumbs Up

Shopping Mall - walkways

Hello,

We are currently preparing a daylight simulation on a shopping malls. The retail stores are tenanted areas and are therefore excluded from the simulation. However, can we consider interconnecting walkways (between one store and another) as regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building. given that:
1) Many shoppers will be using these walkways
2) cleaners and security personel will be working along these corridors
3) There will also be Owner's helpdesks along these corridors to answer visitor's queries

Your opinions are much welcome !

Thanks,

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Todd Reed Daylight Designer, 7group Feb 18 2011 LEEDuser Expert 3569 Thumbs Up

George
I've never seen a space denied being regularly occupied when you are providing daylight to that space, even if it is a corridor. But, depending on how much these corridor spaces are helping you earn the credit or not, may determine if the reviewer accepts your argument.

Typically, corridors and other circulation spaces are not, but static spaces within these corridors can be considered regularly occupied.
Since there are help desks in the corridors, the area around the desk is regularly occupied. The rest of the corridor would not be even though cleaning staff and security is moving through the space. The key is static and dynamic, placing permanent seating in the corridor creating rest areas could be a strategy used that would allow you to use more of the corridor spaces.

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Omar Katanani Feb 28 2011 LEEDuser Member 5313 Thumbs Up

Many thanks for the answer Todd. It seems to me from the uestions and answers below that regularly occupied tenanted areas must also be considered in the calculations. Can you please confirm that this is the case?

Thanks,

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Susan M Kaplan Director of Specifications and Sustainability HLW
Feb 08 2011
LEEDuser Member
582 Thumbs Up

CS project: How do I know the regularly occupied spaces?

Do I need to work with the tenants and base our calculations on their interior fit-out design to evaluate whether we're meeting 75% of all regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building.?

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Todd Reed Daylight Designer, 7group Feb 09 2011 LEEDuser Expert 3569 Thumbs Up

Susan,
No you do not need to work with the tenants with their layout to determine whether it will meet the 75% for 8.1. All that is needed is the areas that could be regularly occupied. Core areas such as elevator lobbies, mechanical spaces do not need to be included.

I would say that it is good practice to involve your tenants so that they can maximize the daylight. Even tenant guidelines could be used.They may not know what was done to provide daylight in the space and could hurt the effort by placing enclosed offices at the window wall and open office in the interior.

If attempting 8.2, you will need to provide possible tenant layout and count. In that case i would use it for 8.1 also for consistency.

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Omar Katanani Mar 02 2011 LEEDuser Member 5313 Thumbs Up

Hi Todd and Suzan,

From what I understand, Tenanted areas should not be included in the daylight simulation. Indeed, the guidance states on p 554 that daylighting in tenanted areas is a LEED for Commercial Interior credit and is therefore not considered in LEED CS. Do you agree ?

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Todd Reed Daylight Designer, 7group Mar 02 2011 LEEDuser Expert 3569 Thumbs Up

George,
Are you attempting CS? You have a mall, is it already occupied with tenants? Or is it just the shell? Is it occupied? The space which will be tenant fit out areas would have to be included. Without digging through CIRs (which the new library for CIRs is terrible) I don;t know of why this space would be excluded.

Some projects just cannot earn some credits. When you start looking to attempt LEED and even daylight after schematic design. then it is search for compliance and not actually designing and building for compliance and performance.

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Susann Geithner Director of Sustainability, HSB Architects & Engineers Mar 02 2011 LEEDuser Expert 7959 Thumbs Up

George, I did 4 LEED CS projects within the last year. Here is how we did it and what the reviewers advised us on. You have to establish a "potential tenant design". This is not necessary, what the tenants actually build. This design has to be consistent throughout the credits/prerequisites. So while developing the tenant design keep in mind that you will also have to consider views IEQ 8.2, comfort controlls IEQ 6, etc.. You than determine the regular occupied areas based on the same definition as for LEED NC. Also you have to include the tenant spaceTenant space is the area within the LEED project boundary. For more information on what can and must be in the LEED project boundary see the Minimum Program Requirements (MPRs) and LEED 2009 MPR Supplemental Guidance. Note: tenant space is the same as project space. into your calculations. You can make assumptions like having offices along the windows and a hallway in the middle, while all walls (Office-hallway) are made of glass. So basically you will show that the building allows for 75% daylight area based on the core & shell and a possible tenant layout.

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Petr Vogel Specialist Consultant, EkoWATT CZ Apr 13 2012 LEEDuser Member 34 Thumbs Up

Susan,

Is it necessary that the submitted drawings of fit-outs will actually match the assumed the most probable actual layout?

We have 7 floor office building. In current design layouts there are 6 floors of small separated offices and 1 floor of open offices. I suppose these drawings that I received do not match the most probable tenant layout. The common real proportion in other buildings developed by the investor is at about 4/3 = open/divided offices which is different from the actual drawings 1/6.

The assumption of 4/3 will be used in EAp2 energy modelling to demonstrate DCV and other energy efficiency measures. Do we have to tell the architect and the MEPs to change their current drawings to open spaces in order to reach the 4/3 proportion and to submit such drawings then coherently for all the credits?

Thanks!

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Sofia Nordström
Nov 19 2010
Guest
28 Thumbs Up

Option 2 prescriptive

Hi, I’m working with a CS project and we have chosen to go for Option 2, the prescriptive path. My issue is that the project consists of an 8 story square building with a large skylight and atrium in the center. I have completed the D&V calculations for the offices which are located around the perimeter of the building; however, when it comes to the offices located on the atrium side, I’m not sure how to calculate the daylighting factor. At the moment, I’m not able to complete the simulation option so I’m how to incorporate the daylighting of these rooms from the atrium and whatever reaches them from the exterior windows through the glass parti-walls.

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Eddy Santosa Sustainable Design Coordinator, HMC Architects Dec 01 2010 LEEDuser Expert 2202 Thumbs Up

Sofia,

I believe you can't use option 2 for your case. The available options for you are option 1 and option 3.

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Omar Katanani
Sep 29 2010
LEEDuser Member
5313 Thumbs Up

Option 3 - Measurement

Hello,

Using this option, the LEED guidance requires to demonstrate through records of indoor light measurements that a minimum daylight illumination level of 25 fc1. A footcandle (fc) is a measure of light falling on a given surface. One footcandle is defined as the quantity of light falling on a 1-square-foot area from a 1 candela light source at a distance of 1 foot (which equals 1 lumen per square foot). Footcandles can be measured both horizontally and vertically by a footcandle meter or light meter. 2. The non-metric measurement of lumens per square foot, one footcandle is the amount of light that is received one foot from a light source called a candela, which is based on the light output of a standardized candle. A common range for interior lighting is 10 to 100 footcandles, while exterior daytime levels can range from 100 to over 10,000 footcandles. Footcandles decrease with distance from the light source. The metric equivalent of a foot candle is 10.76 lux, or lumens per square meter. has been achieved in at least 75% of all occupied areas.

Does anybody know if we also need to demonstrate that the illuminance levels do not exceed the maximum threshold of 500 fc such as in Option 1? It does not seem to be the case ...

Many thanks,

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Oct 08 2010 LEEDuser Moderator

I agree, this does not seem to be the case. As a best practice, though, you'd want to check that this is the case, so that occupants don't suffer from glare and cover up the windows—negating your careful daylighting plan.

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Michelle Cottrell President Design Management Services
Sep 18 2010
LEEDuser Member
339 Thumbs Up

Glare Control for CS project

Has anyone had any luck requiring the tenant to provide interior shading devices (interior blinds or shades) in order to achieve this requirement of the credit? I have a base building where the developer is not including that element in the CS scope. A tenant is already selected for the entire space and will provide interior shades to control glare. Therefore, would it be acceptable to pursue an alternative compliance path as the building will have glare control devices (although supplied by the tenant) in order to earn the credit? Any help is appreciated!

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Eddy Santosa Sustainable Design Coordinator, HMC Architects Sep 24 2010 LEEDuser Expert 2202 Thumbs Up

Hi Michelle,
I believe you do not need to pursue an alternative compliance. A letter from the tenant or a copy of the contract that mentions a tenant that uses entire space of your building provides the glare control, is sufficient.

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Jana Schulz Architect - LEED AP Edificios Verdes
Aug 24 2010
Guest
344 Thumbs Up

Glare control in CS projects

Wwe are working on several CS projects that have good daylight illumination levels. Nevertheless, there are some spaces that go over the 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. limit.
In the LEED form for IEQ8.1 it's obvious that if you don't install glare control you can't get the credit but that doesn't make sense to me. If I have 100,000 sqft of offices and I go over the 500fc limit in only a couple of spaces totaling 1,000 sqft I can't get the credit? Or should I simply deduct that area from the area that complies?
Thanks.

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Eddy Santosa Sustainable Design Coordinator, HMC Architects Aug 29 2010 LEEDuser Expert 2202 Thumbs Up

Hi Jana,
I believe you can deduct the area that does not comply. In addition, I would suggest to take a look your building design, High illuminance level usually means that your room will receive direct sunlight.

Regarding glare control, you may provide luminance/glare study and try to prove that the glare will not be a problem in your space. There are many glare control strategies, outside common strategies mentioned in LEED reference.

In this credit, LEED actually wants to address 2 issues in daylight design such as illuminance level issue and luminance issue. The glare requirement is to address luminance issue, while your simulation/calculation is to address illuminance level issue.

Hope it helps...

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Billy Ng
Jul 30 2010
Guest
463 Thumbs Up

About Design of IEQc8.1

I am working on core and shell project, building a data center. in order to get this credit, i need to have vision glazing or skylight in occupied space. for example a console room, which does not require any natural light or whatsoever. any suggestions

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Aug 04 2010 LEEDuser Moderator

The credit requirements focus on regularly occupied spaces—areas where workers are seated or standing as they work. It sounds like your console room might not be a regularly occupied space, and thus not included under this credit.

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Dushan Milinovich Project Coordinator Kalban Architects
Jun 29 2010
Guest
76 Thumbs Up

Option 2 prescriptive

Hello,

I'm working on a core&shell project and it'll go with option 2, prescriptive.

I can type "Total daylight requlary occupied gross area, determined throught prescriptive calculations" in the blank on the template, but don't know where I should type "Total regularly occupied gross area" to calculate percentage.

Anybody knows it?

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Eddy Santosa Sustainable Design Coordinator, HMC Architects Jul 01 2010 LEEDuser Expert 2202 Thumbs Up

Hi Jiwon,
Could you check: PI FORM 3: OCCUPANT AND USAGE DATA? You may need fill in the information in there.

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Hansong Sun
Apr 05 2010
Guest
171 Thumbs Up

About simulation of IEQc8.1

Hello
I want to get IEQc8.1 through simulation, but I have some problem.
1. There are internal shades in the building, such as blinds, In simulation, Can I use internal shades in the location where direct sunlight will fall. If I don't use internal shades, many illumination values will exceed 500fc.
2. Are rests and corridors in retail 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.?
3. How much feet is the high of simulated work plane?

Thanks

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Jonathan Weiss Apr 05 2010 LEEDuser Member 1674 Thumbs Up

In the reference guide for LEED NCv2009, p 556 they identify shades - see bullet 3
"If the project uses automated shades, the maximum footcandle level does not apply."
This implies that with manually operated shades the maximum level does apply - e.g. you cannot assume that they'll always be operated optimally to minimize glare. A number of studies on daylighting bear this out - most people do not change their blinds frequently, so they end up more closed than open - defeating daylight entry.

The reference guide also discusses 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. - I defer to others with more retail experience on corridors, but restrooms are not considered regularly occupied.

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Juan Robles Senior Architect, AIA, LEED AP BD+C , RoblesArq Architecture and Planning Jul 14 2011 LEEDuser Member 139 Thumbs Up

What happens if we have fixed louvers on an open circulation hallway used to connect the spaces? do i need to take into account that space? it is not an interior space, it will be more as a terrace.

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Jill Dalglish, PE Founder & Senior Engineer, Dalglish Daylighting Jul 14 2011 LEEDuser Expert 2855 Thumbs Up

Hello Juan,
Are you asking if you need to include the hallway space? If so, the answer is no because it is not classified as a regularly occupied space.

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