California and many other states are adopting increasingly stricter daylight related requirements as part of their building energy efficiency standards. These new requirements are intended to reduce electricity usage with energy efficiency.
California has an ambitious goal of decarbonizing buildings and reducing greenhouse gas emissions by at least 40% below the 1990 levels by 2030. To reach this goal, new construction projects must meet CA Energy Code Title 24.
Lighting technology nowadays is very efficient. Lighting manufactures have come up with various lighting control devices, strategies, and features that would yield considerable energy savings. One of the most widely used techniques for lighting control is daylighting control. The advancement in technology allows such technique to meet energy code requirements such as CA Title 24, ASHRAE 90.1, and IECC.
Daylight vs Daylighting: The Difference
1. Daylight is radiation emitted by the sun, including the radiation scattering effects of the atmosphere.
2. On the other hand, Daylighting is also known as Daylighting Control or Automatic Daylight dimming, is a practice of utilizing artificial lights in a room in response to the availability of natural light. Daylighting’s main objective is to maximize visual comfort and to reduce energy use by applying technologies that can adjust the electric lighting output based on available daylight.
Identify the Daylit Zones:
Before we implement Daylighting, we need to identify the Daylit zones of each room. These zones are the areas that are closer to daylight apertures that make Daylighting a possibility. Types of Daylit zones include Primary Sidelit, Secondary Sidelit, and Skylit,
Primary Sidelit Daylit Zone: It is directly opposite the windows and receives a considerable amount of dayliight throughout the day.
Secondary Sidelit Daylit Zone: It is an area not directly opposite a window but still receives a minimum amount of daylight.
Skylit Daylit Zone: It is an area illuminated by one or more skylights. The area of the space equal to the area of the skylight plus a distance 0.7 times the average height of the skylight above the floor, extending out from the edges of the skylight.
TYPES of DAYLIGHTING:
There are 2 main types of daylighting:
Open-Loop Controls:
The light sensor detects and analyzes the available natural light. Based on this intensity level, the output of artificial light is adjusted. In most cases, these sensors are installed in an open area or near the windows. When the sensors detected the natural light, they will Dim/On/Off the lights according to the outside weather.
Closed-Loop Controls:
The light sensor detects and measures both natural and artificial light intensity. Based on the detected light level, the sensor adjusts the artificial light intensity to balance the natural light intensity.
Advantages of Daylighting Control:
- Energy Savings
- Occupant Health and Wellness
- Meet Sustainability Goals
- Better Indoor Experience
- Compliance with Energy Codes and Standards
Summary: Daylight harvesting, a widely used lighting control strategy, is a mandatory requirement for energy code compliance. Moreover, the practice of optimizing the availability of daylight enhances the beauty of space without reducing the comfort level of occupants.
