Classroom Lighting Calculator

Size lighting for K–12 and higher-education classrooms per IESNA RP-3 (Educational Facilities) and ASHRAE 90.1. Includes glare control and board/display zone recommendations.

Room Dimensions

Length 30 ft

Width 28 ft

Ceiling Height 9 ft

Lighting Design

Room Type

Fixture Type

Reflectances (ceiling/wall)

Daylight Contribution 0%

Results

Floor area—

IESNA target (desk level)—

Effective target (w/ daylight)—

Total lumens required—

Fixtures required—

Fixture spacing—

Total wattage—

LPD (W/ft²)—

ASHRAE 90.1 classroom limit—

—

fixtures

Count

—

W/ft²

Power density

—

kW total

Connected load

—

fc avg

At desk level

IESNA RP-3 Design Checklist

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CCT 3000–4000K — Neutral white preferred for classrooms. Avoid >5000K for primary spaces.

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CRI ≥ 80 — Good color rendering for reading, art, and visual tasks. Labs and art rooms: CRI ≥ 90.

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Glare UGR ≤ 19 — Low-glare lens or diffuser required. Direct view of bare LEDs causes visual discomfort and reduced task performance.

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Board/display zone — Install separate fixtures or asymmetric luminaires aimed at the front wall. Target 50–75 fc on board surface.

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Dimming / daylight controls — ASHRAE 90.1 requires continuous dimming in daylit zones. 0–10V or DALI dimming recommended.

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Circadian lighting — Consider tunable white (2700–6500K) for alertness during morning classes and relaxation before dismissal.