Deciphering 2018 IECC—Daylight Responsive Controls

One area that hasn’t changed much with the 2018 IECC revision are the sections specifying how daylight harvesting should work in a compliant facility. That’s because Section C405.2.3, Daylight Responsive Controls, was initially added during the 2015 IECC revision, which revolutionized the technologies and techniques required by the energy standard.

Requirements for qualifying spaces can be quickly summarized as follows:

  • Daylight responsive controls are required in both toplit and sidelit daylight areas
  • These areas must be independently controlled with accessible calibration devices
  • The larger daylighting zones must be controlled independently from general area lighting using either stepped or continuous dimming methods
  • Spaces with multi-level controls must have at least two levels that reduce full-ON in response to ambient light present in the space
    • One level no more than 50-70% of full-ON
    • A second level no more than 35% of full-ON

These changes come down to strategic zoning for spaces that receive natural daylighting from sources like windows, atriums and skylights, and incorporating daylight harvesting technologies (such as photocells and automatic dimming controls) to keep the light even and sufficient throughout an entire space—without wasting overhead lighting when it is not necessary.

Summary of 2015 and 2018 IECC Requirements
C405.2.3 Daylight Responsive Controls

For more information and tools for 2018 IECC, visit

Daylighting Control Solutions from Leviton

Enable automatic and intuitive daylight harvesting controls with Leviton solutions, which offer scalable, customizable options for any type of application.

Provolt™ Room Controller (PRC)

A revolutionary self-contained daylight harvesting solution with a sensor, photocell and power pack integrated in one unit. Enable as little or as many lighting control strategies with the Provolt App—the only setup tool needed.

GreenMAX® DRC Room Control System

Provides a scalable, distributed control system that can manage daylight harvesting for virtually any type of lighting, in any application and building size. Fully configure daylighting settings and zones using the GreenMAX DRC App.

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