ASHRAE 90.1 and Lighting

ASHRAE 90.1 is the American commercial building energy standard, and in Florida it matters for one specific reason: it is an alternate way to comply with the energy code. You may either follow Chapter 4 of the Florida energy code, or follow ASHRAE 90.1 in its entirety. They are two complete rulebooks for the same objective and you have to pick one.

Most people take the code path by default. There are situations where deliberately choosing ASHRAE is worth real money, and one of them is specific to Florida.

Which edition applies here

• Florida's 8th Edition references ASHRAE 90.1-2019. That is the edition to design to on a Florida job today.
• The current published edition is 90.1-2025. The standard runs on a three-year cycle, 2016 to 2019 to 2022 to 2025, so Florida sits two cycles behind the live standard. On a specifier page or a submittal, always write "ASHRAE 90.1-2019, as referenced by the Florida code" rather than just "ASHRAE 90.1", because the difference is not cosmetic.
• Florida does not adopt 90.1-2019 whole. It excludes three sections, and one of them is a lighting requirement.

How Section 9 is built

Section 9 is the lighting section, and its internal structure is the thing to understand, because it decides what you can escape by modeling and what you cannot.

• Section 9.4 is mandatory. Lighting controls, exterior lighting, dwelling units, horticultural lighting. These apply on every compliance route, including whole-building energy modeling. Modeling does not buy you out of a control requirement.
• Sections 9.3 and 9.5 are prescriptive. The Simplified Building Method, the Building Area Method and the Space-by-Space Method, plus the additional interior lighting power allowances. These are power budgets, and power budgets are what a performance model lets you trade against.
• Section 9.2.2.1 lists equipment exempt from lighting power calculations, and 9.1.3 covers alterations.

When choosing ASHRAE is the right call

The trade is broadly this: ASHRAE tends to be tighter on wattage and differently structured on controls. Whether that helps depends on your project.

• Take the code path for track-heavy retail and hospitality. This is the single biggest divergence and it decides projects. ASHRAE charges track lighting at a minimum of 30 watts per linear foot against the budget. The IECC-derived path charges 8. On a hundred feet of track that is 3,000 watts of budget versus 800. If your design leans on track, the code path is worth a great deal.
• Take the code path when you want the daylight-control wattage exception. The code route lets you drop connected power below an adjusted budget instead of installing daylight-responsive controls. In a space where photosensors would be awkward to place or commission, that trade can be worth more than the wattage it costs.
• Take ASHRAE when your design is already lean on wattage and you would rather have the Florida exclusions. If you are comfortably inside the power budget, being relieved of automatic partial-off and automatic receptacle control is a straightforward saving.
• Take ASHRAE when the project is chasing LEED. LEED's energy modeling is built on 90.1 Appendix G anyway. Running one standard instead of two avoids duplicating the model and reconciling two sets of assumptions.

Where the standard has been heading

Even though Florida is on the 2019 edition, the direction of the standard tells you where the code is going, and 90.1-2022 is a preview of the next Florida cycle.

• Interior lighting power fell again in 90.1-2022, about 4 percent overall against 2019, on top of much larger cuts between 2016 and 2019. Open-plan office allowances are down roughly a third across those two cycles.
• The definition of an enclosed office tightened from 250 square feet to 150.
• Retail additional allowances were cut hard in the two highest display categories.
• Daylight control triggers dropped to 75 watts in the primary sidelighted zone and 150 in the secondary.
• Manual dimmers must now dim continuously from full output down to 10 percent or less, replacing the older requirement for a single intermediate step.
• Key-card guest room controls were explicitly prohibited, with guest rooms and switched receptacles required to switch off 20 minutes after vacancy.
• Exterior allowances fell around 30 percent in the common lighting zone, having been flat for the previous cycle.

Common questions

Related: Florida energy code lighting · LEED and lighting · WELL and lighting · Lighting controls guide · LED dimming compatibility