GET CONTROL! combined length of new and retrofitted linear luminaires is greater than 20 linear feet, the alteration must comply with the standard’s lighting power allowance and mandatory control requirements. If the alteration is smaller, it must comply with lighting power allowance requirements (or result in new wattage at least 50 percent below the original wattage of the system) and then be controlled by at least an Off switch.
LIGHTING POWER The 90.1 standard limits maximum lighting power density. Unless opting to use complex building modeling, designers can choose one of two compliance paths, either the Building Area Method (single maximum power allowance in W/sq.ft. for entire building) or Space by Space Method (maximum power allowance for each type of space within building). The standard also caps exterior lighting power using a system of base allowances and tradable surfaces. The 2022 version of 90.1 adjusted Building Area Method power allowances. Exterior lighting power allowances are significantly reduced compared to previous versions of the standard. For interior lighting power, allowances were generally reduced or stayed the same. Also generally, when power allowances were reduced, they were not reduced as significantly as in previous versions, suggesting maturing acceptance of LED by 90.1. Here are some examples:
HORTICULTURAL LIGHTING This new section of 90.1’s lighting section addresses the distinct characteristics of horticultural lighting. Certain horticultural luminaires must achieve a minimum photosynthetic photo efficacy (PPE) and be controlled by a device that automatically turns them off at specific times. PPE is a new metric developed in ANSI/ASABE S640.
GERMICIDAL LIGHTING The 2022 version of 90.1 added power used only for a germicidal function in lamps or luminaires to the list of lighting exempted from being subject to interior power allowances.
TRACK LIGHTING When calculating the wattage of line-voltage track lighting and plug-in busway designed to allow the addition and/or relocation or lighting without system wiring alteration, the 2019 version of 90.1 offered one option being the specified wattage of the system’s lighting with a minimum of 30W/linear foot. The 2022 version reduced the 30W/linear foot to 10W/linear foot in recognition of higher-efficiency LED technology being predominant.
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DECORATIVE AND RETAIL POWER ALLOWANCES When using the Space-by-Space Method to comply with maximum allowed lighting power, an increase is allowed for specific purposes such as decoration (decorative lighting or to highlight art or exhibits that are not exempted by the standard) and supporting retail sales. The 2022 version of 90.1 decreased the additional interior lighting power allowance for decorative lighting from 0.75W/sq.ft. to 0.70W/sq.ft. while also reducing the retail sales area additional power allowances. Additionally, 90.12022 created a new additional power allowance of 0.50W/sq.ft. for interior lighting used for videoconferencing.
LIGHTING CONTROLS ASHRAE/ANSI/IES 90.1-2022 updated the lighting control requirements with several significant tweaks and additions. Occupancy sensing in open offices: Occupancy sensors are required as the automatic shutoff strategy in various spaces, typically smaller, enclosed spaces such as offices smaller than 300 sq.ft.. Now larger offices are included, aligning 90.1 with IECC 2021 and the latest Title 24, Part 6 energy code in California. If the office is 300 sq.ft. or larger, such as open offices, occupancy sensors are required to provide automatic shutoff within 20 minutes of the area being unoccupied. The control zone for each sensor is limited to 600 sq.ft. While the 90.1-2022 standard allows up to 50 percent of the general lighting power to automatically turn on, here all lighting in occupied zones is allowed to turn on to full power. If only some of the control zones in the office are occupied, the general lighting in the unoccupied zones is allowed to automatically turn on to up to 20 percent of full power. This ensures that if say a single zone is occupied, it is surrounded by dim but not dark zones. New threshold for daylight-response controls: Standard 90.1 requires that general lighting in daylight areas feature daylightresponsive controls that independently control the lighting, with exceptions. IECC defines the dimensions of these daylight areas based on whether they are sidelit (adjacent to vertical fenestration such as windows) or toplit (under fenestration such as skylights), with sidelit areas divided into primary (directly adjacent to fenestration) and secondary (directly adjacent to primary) areas. The standard indicates a wattage threshold at which automatic daylight-responsive lighting controls are needed to control general lighting in daylight areas. In the 2022 version, if the total wattage of general lighting either entirely or partially in the primary sidelit area is 75W or greater, daylight-responsive control is required. This threshold was reduced from 150W in the previous version of 90.1. Additionally, if the total wattage of general lighting either entirely or partially in the primary and secondary sidelit areas is 150W or greater, daylight-responsive control is required in both areas, with each area being independently controlled. This was reduced from 300W in the previous version of 90.1. For toplit areas, if the total wattage of all general lighting either entirely or partially in a daylight area under skylights and roof monitors is 75W or greater, daylight-responsive control is required for the area. This was reduced from 150W in the previous version of 90.1. In all of the above cases, the daylight-responsive control will reduce lighting power in response to daylight using continuous