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ASHRAE 90.1 — Energy StandardNECASHRAE 90.1IECCTitle 24OSHA
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ANSI / ASHRAE / IES Standard 90.1

ASHRAE 90.1 Lighting Energy Standard

Energy standard for buildings except low-rise residential — interior and exterior lighting power density (LPD) limits, mandatory controls, and compliance paths.

StandardASHRAE 90.1Current Edition2022ScopeCommercial BuildingsMetricW/ft² LPDSection9 — Lighting
Interior LPD — Space-by-Space Method (Table 9.6.1)
Two compliance paths: (1) Space-by-Space — each space must not exceed its LPD; (2) Building-Area — entire building area type allowed vs. actual installed watts. Space-by-space is more flexible for mixed-use projects.
Space TypeLPD (W/ft²)Notes
Office — Open Plan0.61
Office — Enclosed0.74
Conference / Meeting Room0.97
Corridor0.41Hospitality corridors 0.66
Lobby0.90Hotel lobby 1.06
Restroom / Toilet0.82
Stairwell0.49
Storage0.63
Mechanical / Electrical Room0.95
Classroom / Lecture1.11
Library — Reading Area1.06
Library — Stacks1.71
Cafeteria / Dining0.65
Kitchen / Food Prep1.21
Retail — Sales Area1.44High-end: 2.22
Workshop / Fabrication1.59
Gymnasium / Exercise0.72
Healthcare — Exam Room1.66
Healthcare — Corridor0.89
Parking Garage — Interior0.19
Warehouse — Storage0.33
Building-Area LPD Method (Table 9.5.1)
Building TypeLPD (W/ft²)
Automotive Facility0.82
Convention Center0.82
Courthouse0.89
Dining — Bar / Lounge0.99
Dining — Cafeteria / Fast Food0.90
Dining — Family0.89
Dormitory0.61
Exercise Center / Gymnasium0.72
Fire Station0.71
Grocery Store1.47
Healthcare — Clinic0.87
Healthcare — Hospital1.05
Hotel / Motel0.87
Library1.18
Manufacturing Facility1.11
Multifamily0.51
Museum1.06
Office0.82
Parking Garage0.21
Penitentiary0.81
Performing Arts Theater1.39
Police / Fire Station0.87
Post Office0.87
Religious Building1.00
Retail1.26
School / University0.87
Sports Arena1.10
Transportation0.70
Warehouse0.66
Workshop1.59
Mandatory Lighting Controls — Section 9.4

Occupancy Sensors

Required in: offices ≤250 ft², conference rooms, copy/print rooms, break rooms, classrooms, restrooms, storage, stairwells, and all spaces ≤10,000 ft². Auto-off or auto-off/manual-on.

Daylighting Controls

Mandatory in daylit zones adjacent to windows or under skylights in spaces >150 ft². Multi-level switching or continuous dimming required within the primary and secondary sidelit daylit zones.

Automatic Shut-Off

All lighting must have building-level automatic shut-off (schedule-based or occupancy sensor). Override allowed ≤2 hrs.

Exterior Lighting Controls

Exterior lighting must auto-shut-off when ambient light exceeds 25–35 fc (photosensor) and reduce by ≥30 % during non-operational hours.

Display / Case Lighting

Retail display lighting with separate controls from general lighting. Occupancy sensor or schedule control required.

Hotel Guest Rooms

Master switch at room entry that turns off all fixed luminaires and switched outlets within 20 min of occupant departure.

Exterior Lighting Power Allowances (Section 9.4.2)
ApplicationAllowanceUnit
Main entry (retail)20 + 20W per linear ft of door width + base allowance
Non-main entry20W per linear ft of door width
Uncovered parking0.10W/ft²
Covered parking0.13W/ft²
Building façade (illuminated)0.20W/ft² of illuminated area
Walkways < 10 ft wide0.70W per linear ft
Walkways ≥ 10 ft wide0.14W/ft²
Stairways outdoors0.75W per linear ft of stairway width
Drive-through windows440W per window
Vehicle sales / service areas0.20W/ft²
References
DocumentPublisherDescription
ANSI/ASHRAE/IES Standard 90.1-2022ASHRAEPrimary energy standard; Section 9 governs lighting.
ASHRAE 90.1 User's ManualASHRAEWorked examples and compliance forms.
IES Lighting Handbook, 10th Ed.IESReference illuminance levels used in LPD derivation.
ASHRAE 90.1 Compliance Guide for LightingASHRAE/IESStep-by-step compliance forms.

ELS offers ASHRAE 90.1-compliant luminaire schedules and LPD calculation support. Visit EnterELS.com.