Lighting, Acoustics, and Environmental Quality
This domain tests lighting, acoustics, and environmental quality: quantitative lighting calculations, lamp and control selection, acoustic metrics, and indoor air quality. Expect straightforward calculations plus judgment about comfort and code compliance.
Core rules
- Lighting: footcandles = lumens x coefficient of utilization x light loss factor / area. Use maintained illuminance and the correct CU for the room.
- Color: CCT describes warmth/coolness; CRI or TM-30 describes color rendering. Efficacy is lumens per watt.
- Controls should match use: occupancy sensors, daylight dimming, and manual dimming reduce energy but must be commissioned.
- Acoustics: STC measures airborne sound isolation between rooms; NRC measures absorption within a room; background noise and reverberation affect speech privacy.
- Environmental quality: specify low-VOC materials, ventilation per ASHRAE 62.1, and moisture control; avoid specifying products that trap moisture.
Worked example
A 20-ft by 30-ft room is 600 sf and needs 30 fc. Each luminaire delivers 3,000 lumens, CU = 0.70, LLF = 0.80. Lumens required = 30 x 600 = 18,000. Delivered lumens per fixture = 3,000 x 0.70 x 0.80 = 1,680. Fixtures = 18,000 / 1,680 = 10.7, so specify 11. If the design uses 10 fixtures, expected illuminance is about 28 fc, which may be acceptable for circulation but not for detailed tasks.
Traps
- Mixing footcandles and lux (1 fc = 10.76 lux).
- Using initial lumens instead of maintained lumens or ignoring LLF.
- Confusing STC with NRC.
- Specifying low-VOC paint but ignoring adhesives, sealants, and composite wood.