DASLab / 08
Daylight & Ventilation
Window-to-floor ratios, daylight factor estimates, and cross-ventilation opening sizes.
Experimental tool — evolving and open to suggestions: info@derzawi.com
Average daylight factor
2.4%
Adequate daylight
Window-to-floor ratio19%Rule of thumb ≥ 15–20% for habitable rooms
Limiting depth (BRE)6 m ≥ room depth · OK
Visible sky angle θ75°
Wind-driven (cross)
Airflow450 L/s
Air changes24.1 ACH
Opening for 5 ACH0.12 m²
Q = Cv · A · v (ASHRAE Fundamentals). Cross-ventilate rooms up to ≈ 14 m deep (5 × H).
Stack-driven
Airflow282 L/s
Air changes15.1 ACH
Opening for 5 ACH0.13 m²
Q = Cd · A · √(2gΔH·ΔT/Ti), Cd 0.65. Single-sided ventilation works to ≈ 7 m deep (2.5 × H, CIBSE AM10).
Early-stage estimates. Use climate-based daylight modelling and ventilation/overheating simulation for design stage.