LEED (BD+C)- Indoor Environmental Quality Credit: Daylight

LEED (Leadership in Energy and Environmental Design) certification is a globally recognized symbol of sustainability achievement in building design and operation. One of the key areas of focus for LEED certification is indoor environmental quality (EQ). Among the various EQ credits, daylight is one of the most important ones. Daylight not only enhances the aesthetics of a building but also has a significant impact on occupant health and well-being. In this article, we will explore the LEED Indoor Environmental Quality credit for daylight and its requirements.

The objective of the LEED EQ credit for daylight is to connect building occupants with the outdoors, reinforce circadian rhythms, and reduce the use of electrical lighting by introducing daylight into the space. The credit requires providing manual or automatic glare-control devices for all regularly occupied spaces. Additionally, the credit offers three options to demonstrate compliance:

Option 1: Simulation – Spatial Daylight Autonomy and Annual Sunlight Exposure

The first option requires demonstrating through annual computer simulations that spatial daylight autonomy 300/50% (sDA300/50%) of at least 55%, 75%, or 90% is achieved. The sDA metric measures the percentage of regularly occupied floor area that receives a minimum daylight level of 300 lux for 50% of operating hours annually. Healthcare projects should use the perimeter area determined under EQ Credit Quality Views. Points are awarded based on the sDA achieved, as shown in Table 1.

Option 2: Simulation – Illuminance Calculations

The second option requires demonstrating through computer modeling that illuminance levels will be between 300 lux and 3,000 lux for 9 a.m. and 3 p.m., both on a clear-sky day at the equinox. The credit requires achieving the illuminance levels for the percentage of regularly occupied floor area or the perimeter area determined under EQ Credit Quality Views. Points are awarded based on percentage of floor area that meets the criteria, as shown in Table 2.

Option 3: Measurement – Daylight Factor

The third option requires measuring the daylight factor for regularly occupied spaces. The daylight factor is the ratio of the indoor illuminance level to the outdoor illuminance level. Points are awarded based on the percentage of floor area that meets the criteria.

The LEED EQ credit for daylight is an important aspect of sustainable building design. The credit not only improves the visual comfort of occupants but also has a significant impact on their health and well-being.