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LEED v2009
Core & Shell
Indoor Environmental Quality
Daylight and Views—Daylight

LEED CREDIT

CS-2009 IEQc8.1: Daylight and views - daylight 1 point

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LEEDuser expert

TODD REED

7group / Energy Opportunities
Daylight Designer

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Credit language

USGBC logo

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

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 Spaces Points
75% 1
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.

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Frequently asked questions

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?

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When should daylight measurements be taken?

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Do I need to have glare control devices?

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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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Credit achievement rate

XX%

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LEEDuser expert

TODD REED

7group / Energy Opportunities
Daylight Designer

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USGBC logo

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

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 Spaces Points
75% 1
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%

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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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  • Tracking spreadsheets for materials purchases.
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  • Sample templates to help guide your narratives and LEED Online submissions.
  • Examples of actual submissions from certified LEED projects.

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.)

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.)

LEEDuser expert

TODD REED

7group / Energy Opportunities
Daylight Designer

See all LEEDuser forum discussions about this credit » Subscribe to new discussions about CS-2009 IEQc8.1