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LEED v2009
Commercial Interiors
Indoor Environmental Quality

Daylight and Views—Daylight

LEED CREDIT

CI-2009 IEQc8.1: Daylight and views - daylight 1-2 points

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© Copyright U.S. Green Building Council, Inc. All rights reserved.

Requirements

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

Regularly Occupied Spaces

Points

75%

1

90%

2

Option 1. Simulation
Demonstrate through computer simulation that the applicable spaces achieve daylight illuminance levels of a minimum of 10 footcandles (fc) (108 lux) 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 (WFR) 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 ASTM 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. See all forum discussions about this credit »

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Frequently asked questions

When should daylight measurements be taken?

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Do I need to have glare control devices?

The answer to this question is available to LEEDuser premium members. Start a free trial »

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Where can I find the Supplemental Views and Daylight Calculator?

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

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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?

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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, roof monitors, tubular daylighting devices such as Solatube, roof overhangs, or shared daylighting scenarios?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

See all forum discussions about this credit »

Addenda

1/15/2016Updated: 4/7/2016
Form Update
Description of change:
Campus Applicable
No
Internationally Applicable:
No
1/8/2010Updated: 2/14/2015
Reference Guide Correction
Description of change:
Insert the term "Tenant space" in alphabetical order with the accompanying text "Tenant 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."
Campus Applicable
No
Internationally Applicable:
No
5/9/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace section with that of the supplementary document.
Campus Applicable
No
Internationally Applicable:
No
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Revise the definition for regularly occupied spaces to be, "Regularly 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."
Campus Applicable
No
Internationally Applicable:
No
5/9/2011Updated: 2/14/2015
Rating System Correction
Description of change:
Replace section with that of the supplementary document.
Campus Applicable
No
Internationally Applicable:
No
12/2/2009Updated: 2/14/2015
Reference Guide Correction
Description of change:
Insert the term "Bay" in alphabetical order with the accompanying text "A bay is a component of a standard, rectilinear building design. It is the open area defined by a building element such as columns or a window. Typically, there are multiple identical bays in succession."
Campus Applicable
No
Internationally Applicable:
No
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for non-regularly occupied space, "Non-regularly occupied spaces are spaces that occupants pass through, or spaces used in pursuit of focused activities for less than one hour per person per day (on average)."
Campus Applicable
No
Internationally Applicable:
No
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for nonoccupied spaces, "Nonoccupied spaces are defined as spaces designed for equipment and machinery or storage with no human occupancy except for maintenance, repairs, and equipment retrieval."
Campus Applicable
No
Internationally Applicable:
No
10/1/2012
LEED Interpretation
Inquiry:

We would like to submit a CIR to request a streamlined approach for the daylight documentation. We have the particular condition of an identical cluster of office buildings. In spite of having the same foot print, each building will be uniquely impacted by orientation variation and specific surrounding context condition. The intent is to fully document one building showing that the amount of light increases as you move up through the floor plates. Then to proceed to document the worst case scenario of each building (ground floor) or the level that is least exposed to solar access. If the worst case scenario passes, then we infer based on our test case that the upper floors of the building will pass as well. This will help us streamline not only the documentation process for so many buildings but also the review process. Is this an acceptable documentation method for this credit?

Ruling:

The project team is requesting whether a campus credit may be pursued for IEQc8.1. Daylight and Views: Daylight through a typical floor plan and worst case scenario daylight calculations.Yes, the typical floor plan and worst-case scenario daylight calculations may be used for the campus credit and applied to all buildings within the master site that have identical floor plans. The 2010 Application Guide for Multiple Buildings and On-Campus Projects identifies IEQc8.1 as an individual building credit and states that each building should pursue the credit individually. However, in the same way that a multi-story building may provide a single floor plan for each grouping of identical floors, if buildings within the Master Site are identical, the same documentation may be used for each identical building. Any of the calculation methods (simulation, prescriptive, measurement) may be used. Documentation for the campus credit and associated projects must demonstrate how the worst case scenario was determined and that the only difference in the buildings is the orientation on the site. The footprint, square footage and interior layout of the buildings must be identical. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
4/1/2013
LEED Interpretation
Inquiry:

The project team would like to exclude laboratory spaces from the list of regularly occupied spaces for the Daylighting and Views calculations. The laboratory spaces are separated from other building areas but efforts have been made to provide exterior views out of the lab spaces by providing fire rated windows around the lab into the surrounding hallways and drive aisle. The laboratory areas will be used solely for research and development purposes and for proprietary reasons & secrecy concerns of the areas, exterior windows have been specifically excluded from these rooms as they will be secure internal rooms being used by a very small percentage of the building occupants.

Ruling:

"The project team is requesting that laboratory spaces be excluded from the requirements for daylight and views (credits IEQc8.1 Daylight and Views: Daylight, IEQc8.2 Daylight and Views, and IEQc2.4: Daylight and Views.) for security reasons and/or due to infrequency of use.

No, the laboratory spaces may not be excluded from daylight and views. It is unacceptable to exclude spaces from the daylight and views calculations due to security reasons. Additionally, based on the information provided, the laboratory spaces may not be excluded for infrequency of use because the spaces are typically occupied for more than one hour per day. The percentage of building occupants using the space is irrelevant. The frequency of use for regularly occupied spaces was further clarified in the definition of a regularly occupied space included in the LEED Reference Guide for Green Building Design and Construction, 2009 Edition addenda dated 11/1/2011 which states that regularly 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."" Applicable Internationally."

Campus Applicable
No
Internationally Applicable:
Yes
4/10/2007
LEED Interpretation
Inquiry:

One wall of our building is a curtain wall. This curtain wall contains 4 different types of glazing, each with a different visible transmittance value, all within one room. We propose using the average visible transmittance value of the four types of glazing to do daylighting calculations for areas adjacent to the curtain wall. Please advise whether this approach is acceptable.

Ruling:

No, the method described of taking the overall average visible transmittance value of all four types of glazing within the curtain wall and using it for all areas adjacent to the curtain wall is not an acceptable means of calculating the daylight factor of the areas in question. However, doing a weighted average of the visible transmittance value (Tvis) of all the glazing classified as daylight glazing and a weighted average of the visible transmittance values of all the glazing classified as vision glazing on a room by room basis would be acceptable. This methodology would effectively take into account the window geometry and associated minimum visible transmittance values. Alternatively, the project team may elect to perform a daylight simulation model to demonstrate credit compliance. See the LEED NC v2.1 EQc8.1 ruling dated 6/21/2004 for guidance on pursuing this approach. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
See all forum discussions about this credit »

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XX%

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© Copyright U.S. Green Building Council, Inc. All rights reserved.

Requirements

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

Regularly Occupied Spaces

Points

75%

1

90%

2

Option 1. Simulation
Demonstrate through computer simulation that the applicable spaces achieve daylight illuminance levels of a minimum of 10 footcandles (fc) (108 lux) 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 (WFR) 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 ASTM 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.

XX%

Upgrade to LEEDuser Premium to see how many projects achieved this credit. Try it free »

Got the gist of IEQc8.1 but not sure how to actually achieve it? LEEDuser gives step-by-step help. Premium members get:

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  • Guidance documents on arcane LEED issues.
  • Sample templates to help guide your narratives and LEED Online submissions.
  • Examples of actual submissions from certified LEED projects.

When should daylight measurements be taken?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

Do I need to have glare control devices?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

Where can I find the Supplemental Views and Daylight Calculator?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

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

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

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?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

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, roof monitors, tubular daylighting devices such as Solatube, roof overhangs, or shared daylighting scenarios?

The answer to this question is available to LEEDuser premium members. Start a free trial »

(If you're already a premium member, log in here.)

1/15/2016Updated: 4/7/2016
Form Update
Description of change:
Campus Applicable
No
Internationally Applicable:
No
1/8/2010Updated: 2/14/2015
Reference Guide Correction
Description of change:
Insert the term "Tenant space" in alphabetical order with the accompanying text "Tenant 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."
Campus Applicable
No
Internationally Applicable:
No
5/9/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace section with that of the supplementary document.
Campus Applicable
No
Internationally Applicable:
No
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
Revise the definition for regularly occupied spaces to be, "Regularly 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."
Campus Applicable
No
Internationally Applicable:
No
5/9/2011Updated: 2/14/2015
Rating System Correction
Description of change:
Replace section with that of the supplementary document.
Campus Applicable
No
Internationally Applicable:
No
12/2/2009Updated: 2/14/2015
Reference Guide Correction
Description of change:
Insert the term "Bay" in alphabetical order with the accompanying text "A bay is a component of a standard, rectilinear building design. It is the open area defined by a building element such as columns or a window. Typically, there are multiple identical bays in succession."
Campus Applicable
No
Internationally Applicable:
No
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for non-regularly occupied space, "Non-regularly occupied spaces are spaces that occupants pass through, or spaces used in pursuit of focused activities for less than one hour per person per day (on average)."
Campus Applicable
No
Internationally Applicable:
No
11/1/2011Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for nonoccupied spaces, "Nonoccupied spaces are defined as spaces designed for equipment and machinery or storage with no human occupancy except for maintenance, repairs, and equipment retrieval."
Campus Applicable
No
Internationally Applicable:
No
10/1/2012
LEED Interpretation
Inquiry:

We would like to submit a CIR to request a streamlined approach for the daylight documentation. We have the particular condition of an identical cluster of office buildings. In spite of having the same foot print, each building will be uniquely impacted by orientation variation and specific surrounding context condition. The intent is to fully document one building showing that the amount of light increases as you move up through the floor plates. Then to proceed to document the worst case scenario of each building (ground floor) or the level that is least exposed to solar access. If the worst case scenario passes, then we infer based on our test case that the upper floors of the building will pass as well. This will help us streamline not only the documentation process for so many buildings but also the review process. Is this an acceptable documentation method for this credit?

Ruling:

The project team is requesting whether a campus credit may be pursued for IEQc8.1. Daylight and Views: Daylight through a typical floor plan and worst case scenario daylight calculations.Yes, the typical floor plan and worst-case scenario daylight calculations may be used for the campus credit and applied to all buildings within the master site that have identical floor plans. The 2010 Application Guide for Multiple Buildings and On-Campus Projects identifies IEQc8.1 as an individual building credit and states that each building should pursue the credit individually. However, in the same way that a multi-story building may provide a single floor plan for each grouping of identical floors, if buildings within the Master Site are identical, the same documentation may be used for each identical building. Any of the calculation methods (simulation, prescriptive, measurement) may be used. Documentation for the campus credit and associated projects must demonstrate how the worst case scenario was determined and that the only difference in the buildings is the orientation on the site. The footprint, square footage and interior layout of the buildings must be identical. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
4/1/2013
LEED Interpretation
Inquiry:

The project team would like to exclude laboratory spaces from the list of regularly occupied spaces for the Daylighting and Views calculations. The laboratory spaces are separated from other building areas but efforts have been made to provide exterior views out of the lab spaces by providing fire rated windows around the lab into the surrounding hallways and drive aisle. The laboratory areas will be used solely for research and development purposes and for proprietary reasons & secrecy concerns of the areas, exterior windows have been specifically excluded from these rooms as they will be secure internal rooms being used by a very small percentage of the building occupants.

Ruling:

"The project team is requesting that laboratory spaces be excluded from the requirements for daylight and views (credits IEQc8.1 Daylight and Views: Daylight, IEQc8.2 Daylight and Views, and IEQc2.4: Daylight and Views.) for security reasons and/or due to infrequency of use.

No, the laboratory spaces may not be excluded from daylight and views. It is unacceptable to exclude spaces from the daylight and views calculations due to security reasons. Additionally, based on the information provided, the laboratory spaces may not be excluded for infrequency of use because the spaces are typically occupied for more than one hour per day. The percentage of building occupants using the space is irrelevant. The frequency of use for regularly occupied spaces was further clarified in the definition of a regularly occupied space included in the LEED Reference Guide for Green Building Design and Construction, 2009 Edition addenda dated 11/1/2011 which states that regularly 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."" Applicable Internationally."

Campus Applicable
No
Internationally Applicable:
Yes
4/10/2007
LEED Interpretation
Inquiry:

One wall of our building is a curtain wall. This curtain wall contains 4 different types of glazing, each with a different visible transmittance value, all within one room. We propose using the average visible transmittance value of the four types of glazing to do daylighting calculations for areas adjacent to the curtain wall. Please advise whether this approach is acceptable.

Ruling:

No, the method described of taking the overall average visible transmittance value of all four types of glazing within the curtain wall and using it for all areas adjacent to the curtain wall is not an acceptable means of calculating the daylight factor of the areas in question. However, doing a weighted average of the visible transmittance value (Tvis) of all the glazing classified as daylight glazing and a weighted average of the visible transmittance values of all the glazing classified as vision glazing on a room by room basis would be acceptable. This methodology would effectively take into account the window geometry and associated minimum visible transmittance values. Alternatively, the project team may elect to perform a daylight simulation model to demonstrate credit compliance. See the LEED NC v2.1 EQc8.1 ruling dated 6/21/2004 for guidance on pursuing this approach. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
See all LEEDuser forum discussions about this credit » Unsubscribe from discussions about CI-2009 IEQc8.1