California Green Building Code (CALGreen) – Daylight
Daylight is essential for proper mental and physical health. Studies have shown that it boosts productivity in a work environment. Bringing daylight into habitable spaces reduces the need of providing artificial lights. CALGreen code has an elective measure to design buildings with daylight design in mind. The code language is as follows.
CALGreen Code Section A5.507.2: Daylight.
Provide daylit spaces as required for toplighting and sidelighting in the California Energy Code. In constructing a design, consider the following:
1. Use of light shelves and reflective room surfaces to maximize daylight penetrating the rooms.
2. Means to eliminate glare and direct sun light, including through skylights.
3. Use of photosensors to turn off electric lighting when daylight is sufficient.
4. Not using diffuse daylighting glazing where views are desired.
CALGreen Code Section A5.507.3: Views.
Achieve direct line of sight to the outdoor environment via vision glazing between 2 feet 6 inches and 7 feet 6 inches above finish floor for building occupants in 90 percent of all regularly occupied areas as demonstrated by plan view and section cut diagrams.
CALGreen Code Section A5.507.3.1: Interior office spaces.
Entire areas of interior office spaces may be included in the calculation if at least 75 percent of each area has direct line of sight to perimeter vision glazing.
CALGreen Code Section A5.507.3.2: Multi-occupant spaces.
Include in the calculation the square footage with direct line of sight to perimeter vision glazing.
Exceptions to Sections A5.507.2 and A5.507.3: Copy/printing rooms, storage areas, mechanical spaces, restrooms, auditoria and other intermittently or infrequently occupied spaces or spaces where daylight would interfere with use of the space.
Intent:
The purpose of these measures is to achieve building lighting through the use of daylight and to provide sightlines to outdoor environments whenever possible. This reduces the need for electrical lighting during normal operations hours and saves energy. It also creates a pleasant ambience f high-quality light and views, which may have a salutary effect on building occupants, such as reducing eyestrain exacerbated by increasing use of electronic devices in the workplace. The California Energy Code regulates energy use associated with electrical lighting, and with toplighting and sidelighting by daylight.
Compliance Method:
Provide in the construction documents means of achieving daylighting and views on the project while minimizing glare and direct sunlight. Wall and ceiling finishes and colors may need to be identified on a finish schedule. Make sure that compliance with the California Energy Code is achieved.
Enforcement:
Plan intake: The plan reviewer should confirm in the construction documents that daylighting strategies and line-of-sight calculations or methods are employed on the project. Verifying the California Energy Code compliance is shown.
On-site enforcement: The inspector should verify that daylighting features are installed and view access is provided as shown, and that the building complies with provisions in the California Energy Code.
(Excerpted from ‘Guide to the 2019 California Green Building Standards Code Nonresidential’ – Chapter 5)
