Lighting, Acoustics, and Indoor Environmental Quality
Lighting, Acoustics, and Indoor Environmental Quality
This domain connects human comfort to measurable design. Lighting: know footcandles and lux (1 fc ≈ 10.76 lux), correlated color temperature, CRI, glare metrics such as UGR, lighting power density, daylighting, and layered controls. Acoustics: distinguish STC (airborne separation), IIC (impact isolation), NRC (absorption), and background noise criteria such as NC. IEQ covers ventilation per ASHRAE 62.1, thermal comfort per ASHRAE 55, moisture control, and low-VOC materials.
Core rules
- Specify light for the task, then control it; high illuminance with glare is not good lighting.
- Use absorption to control reverberation, isolation to block noise, and layout to reduce disturbance.
- Verify ventilation, filtration, and exhaust in rooms with chemicals or moisture.
- Select materials by emissions and cleanability, not “green” labels alone.
Worked example
A 20 × 30 × 9 ft conference room has volume 5,400 ft³ and 300 sabins of absorption. Sabine’s formula gives RT60 = 0.049 V/A = 0.049 × 5,400 ÷ 300 = 0.88 s. For speech, target about 0.6 s, so required absorption = 0.049 × 5,400 ÷ 0.6 = 441 sabins. Add at least 141 sabins, then check that the treatment does not over-absorb at high frequencies or leave flutter echo.
Traps
Confusing STC with NRC; using IIC for airborne noise; ignoring flanking paths and HVAC background noise; and treating a lighting calculation as a layout without checking glare and controls.