Daylight modeling

Daylight modeling

Intent: 

To support circadian and psychological health by setting thresholds for indoor sunlight exposure.

BACKGROUND

Exposure to appropriate amounts of natural light reinforces the alignment of our circadian rhythms and reduces dependence on electricity for artificial lighting; however, excessive sunlight, during can cause glare and unwanted visual contrast. This is not only important to consider throughout the course of the day, but also throughout the course of the year, such that occupants are able to enjoy the benefits of daylight exposure in all seasons. Therefore, it is necessary to find a balance between Spatial Daylight Autonomy (sDA), which measures the percentage of floor area that receives adequate sunlight, and Annual Sun Exposure (ASE), which measures the percentage of floor area receives too much direct sunlight.

Part 1
Healthy Sunlight Exposure

Lighting simulations demonstrate that the following conditions are expected:
a.1
Spatial daylight autonomy (sDA300,50%) is achieved for at least 55% of regularly occupied space. In other words, at least 55% of the space receives at least 300 lux [28 fc] of sunlight for at least 50% of operating hours each year.
b.1
Annual sunlight exposure (ASE1000,250) is achieved for no more than 10% of regularly occupied space. In other words, no more than 10% of the area can receive more than 1,000 lux [93 fc] for 250 hours each year.