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.

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:

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 of the building with dwelling units.

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

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

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:

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 building 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.

Permanent furniture partitions or other permanent features that measure above 42 inches or 106 centimeters are considered obstructions of natural daylight. Areas behind these obstructions should not to be included in the daylit area. Window head height is the height of the window measured from the finished floor level to the top of the window frame.

If there are spaces behind walls and obstructions: Subtract those areas behind obstructions from the total area with access to daylight (A+B). These obstructed areas include spaces behind partitions 42 inches or higher as well as enclosed rooms. The final formula would appear like this: ((A+B) - area behind obstructions) / C

Compliance Documentation

Types of compliance documentation required:

• Annotated design drawings
• Annotated plans
• Certified statements
• Calculations
• Annotated photographs