Nonresidential Lighting Controls: Partial-ON Occupancy Sensors2016 Title 24 CASE Topics
This measure covers lighting controls modifications for nonresidential buildings. The measure descriptions for each specific sub-measure are provided below.
Partial-ON Controls Requirements
The existing lighting controls in Title 24 do not require partial-ON lighting controls. There is an existing power adjustment factor (PAF) in Table 140.6-A that provides an adjustment to the lighting power (LPD) for spaces that include a partial-ON control approach (0.20 factor). There is a second PAF in Table 140.6-A that is intended for a combined Partial-ON and manual dimming control approach (0.25 factor).
The partial-ON requirement has now been employed in ASHRAE 90.1-2013 as a minimum required measure (in conjunction with a manual-ON option) for a select set of suitable space types in buildings. As a result, this approach has the general support of the design community.
The intent of this proposal is to remove the two PAF allowances and add language to Section 130.1(c)5 that will mandate the use of partial-ON occupancy sensors in applications listed in that section as appropriate. These include:
- Offices smaller than 250 square feet
- Multipurpose Rooms smaller than 1,000 square feet
- Classrooms of any size
- Conference Rooms of any size
Occupancy Sensor Maximum Delay Time Requirement
The current language in Sections 130.1 or 110.9 does not define a maximum delay time for programming occupancy sensors under normal circumstances. Section 1605.3(L)(2)(G)1 of Title 20 (the California Appliance Standards) defines the maximum delay time that is permitted to be available in an occupancy sensor device sold in California is 30 minutes, however, that should not be considered appropriate guidance for a delay time under normal design circumstances because most spaces are functionally adequate with much shorter delay times.
Further, without specific guidance in Title 24, a sensor is permitted to operate up to that 30 minute delay time, and the inspection cannot reject the device despite the excessively long delay time. A delay time of 30 minutes will result is considerable energy savings opportunities lost throughout the day and into the evening.
For this reason, and in keeping with the general recommendations that are also established in ASHRAE 90.1, the intent is to add a maximum delay time to Section 110.9(b)4 to limit the delay time to a maximum of 20 minutes in all circumstances. This maximum will also be added to the acceptance testing process for occupancy sensors.
Note, however, that this is not a recommended change to the Title 20 Appliance Standards, which sets the maximum delay time for occupancy sensors at 30 minutes. The Title 20 Standards establishes the maximum time that the device is permitted to be commissioned to in an installation. This proposal establishes a maximum time for sensor programming in an installation. As a matter of course, it is possible for an owner to change the delay time up to 30 minutes under circumstances where this is a more appropriate delay time once the building has gained its occupancy permit.
Several stakeholder meetings and CEC staff workshops were held regarding the Nonresidential HVAC Economizer Modifications building energy efficiency topic. The list of past meetings and hearings can be found here. If you would like to receive email updates on this CASE topic, click the link below.