07. Dwelling Units - Daylighting Access in Dwelling Units

Provide access to natural daylight

Rationale: Implementing design strategies, such as high-visible light transmittance and optimal window-to-wall ratios, increases access to natural daylight, which supports circadian rhythm regulation — contributing to wide-ranging health benefits including improved sleep quality, a strengthened immune system, and lower stress levels.

For the most accurate strategy and documentation requirements, please refer to the digital scorecard made available on the Fitwel Platform.

Requirements

Demonstrate compliance with one of the options below:

Option 1 - Natural Daylight Window-to-Wall Ratio (Full Credit):

Provide access to natural daylight by meeting all of the following requirements:    

Low-Rise Residential with shared interior spaces (LR+), Low-Rise Residential with no shared interior spaces (LR)

1. Ensure that all windows within all dwelling units can exceed a Visible Light Transmittance (VLT) of 40%.
2. Provide a minimum window-to-wall ratio of 35% on each floor all buildings with dwelling units.

Option 2 - Natural Daylight Simulation Score (Full Credit):

Provide access to natural daylight for each dwelling unit that meets the following:    

Low-Rise Residential with shared interior spaces (LR+), Low-Rise Residential with no shared interior spaces (LR)

1. Ensure an average sDA300,50% is achieved for a minimum of 60% of the floor area of each dwelling unit.

Option 3 - Natural Daylight Calculation (Full Credit):

Provide access to natural daylight by demonstrating compliance with the following:    

Low-Rise Residential with shared interior spaces (LR+), Low-Rise Residential with no shared interior spaces (LR)

1. Ensure that all windows within all dwelling units can exceed a Visible Light Transmittance (VLT) of 40%.

2. Ensure that 51% of each dwelling unit within the project includes access to natural daylight.

   Qualifying Calculation:

   To calculate the total percentage of access to daylight within each dwelling unit, follow the steps below and input the required values in the tables on the calculation tab to apply the following formula [((A + B) / C) x 100)]:

   • Step 1, determine C: establish the total area of the dwelling unit.
   • Step 2, determine A and B: establish the area with access to daylight, using the windows located in the dwelling unit identified for C in Step 1 by applying the following:
     • (i) to determine A, identify each window with access to daylight for north and south façades and input the required values in the table for each identical window with access to daylight to apply the following formula: North and South façades Area with Access to Daylight = [(Window(s) Head Height x 1.5) x (Window(s) Width + 2 feet from the right side of the window(s) + 2 feet from the left side of the window(s))].
     • (ii) to determine B, identify each window with access to daylight for east and west façades and input the required values in the table for each identical window with access to daylight to apply the following formula: East and West façades Area with Access to Daylight = [(Window(s) Head Height) x (Window(s) Width)].
     • (iii) repeat steps (i) and (ii) on each unique window type within the space.
     • (iv) determine A and B by adding the results calculated from Step (i) and (ii).
   • Step 3, determine the percentage: to determine the percentage of the dwelling unit with access natural daylight, apply the formula [((A + B) / C) x 100)].
   • Step 4, repeat steps 1 through 3 for each unique dwelling unit floorplan within the project.

Compliance Documentation

Design Pathway (LR+, LR)

• Requirement 1:
  • Checkbox to certify that all windows within all dwelling units can exceed a Visible Light Transmittance (VLT) of 40%.      
  • Upload glazing specifications showing the VLT level of the windows for each group of typical buildings.      
• Requirement 2:
  • Checkbox to certify that 51% of each dwelling unit within the project will include access to natural daylight.      
  • Upload a calculation detailing the planned percentage of daylit area within the dwelling units.   
  • Upload an annotated plan or design drawing for each unique floorplan identifying the following within each unique dwelling unit:
    • areas that will have access to natural daylight
    • areas that will be behind obstructions.           

Built Pathway (LR+, LR)

• Requirement 1:
  • Checkbox to certify that all windows within all dwelling units can exceed a Visible Light Transmittance (VLT) of 40%.     
  • Upload glazing specifications showing the VLT level of the windows for each group of typical buildings.      
• Requirement 2:
  • Checkbox to certify that 51% of each dwelling unit within the project includes access to natural daylight.     
  • Upload a calculation detailing the percentage of daylit area within the dwelling units.   
  • Upload an annotated plan or design drawing for each unique floorplan identifying the following within each unique dwelling unit:
    • areas with access to natural daylight
    • areas behind obstructions.