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Nonresidential Daylighting

Proposal Description

This code change would revise the automatic daylighting controls exceptions. The measure adjusts the wattage thresholds that apply to skylit zones as well as both the Primary Sidelit Daylit Zones (PSDZs) and Secondary Sidelit Daylit Zones (SSDZs). The change rewrites the daylighting controls requirements in Section 130.1(d) and Section 160.5(b)4D. This action would transform the threshold wattage from an exception into a requirement and reduce the threshold for requiring automatic daylighting controls from 120 watts to 75 watts per space by daylit zone type. An exception is provided for the SSDZs when the corresponding PSDZs are not required to implement automatic daylighting controls; in such cases, the threshold for the SSDZs is 85 watts. This revision reflects the appropriate threshold wattage based on the cost of current daylight responsive controls cost of dimming LED (light emitting diode) light sources.

The 120-watt threshold for requiring automatic daylighting controls has been in place for multiple code cycles. It remained unchanged when the basis for indoor lighting power densities was changed to Light Emitting Diodes (LEDs) in the 2019 code cycle. This means the 120-watt threshold now represents significantly a larger daylit area is needed to trigger the requirement for photocontrols. The cost of daylighting controls has dropped, but the primary cost reduction is due to LED general lighting luminaires capable of dimming to 10 percent having no or negligible added costs.

Relevant Documents

CASE Report

Round Two Utility-Sponsored Stakeholder Meeting Materials

Round One Utility-Sponsored Stakeholder Meeting Materials

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