Design Tools
Ventilation Planner
Good ventilation is planned, not left to chance. Select a room and enter its floor area to get guidance on opening size, placement and whether you need mechanical exhaust.
Living / Drawing Room · 150 sq. ft.
Minimum opening
15 sq. ft.
10% of floor area
Ideal opening
22.5 sq. ft.
15% of floor area
Placement guidance
- Openings on two different walls where possible, to allow cross-ventilation.
- Larger openings on the wall facing the prevailing breeze direction.
- Keep at least one high-level ventilator to let hot air escape.
Living rooms benefit most from cross-ventilation — a single-wall window relies entirely on wind pressure changes to move air.
This is general design guidance based on common residential practice, not a structural or local building-code compliance certification. Confirm final openings with your architect or our design team.
How to use this tool
- Select the room — each room type has its own ventilation needs.
- Enter the floor area in square feet.
- Read the minimum and ideal opening area. This is the combined area of windows and ventilators that can actually open, not the glass area.
- Check the placement guidance and whether the room needs mechanical exhaust, then share the result with your architect before window sizes are fixed.
Frequently Asked Questions
How big should windows be for good ventilation?
As a working rule, openable window and ventilator area is sized at roughly 10–16% of the floor area, with kitchens needing more. The planner gives a room-specific minimum and ideal figure based on that practice.
Does a kitchen need an exhaust fan or chimney?
Yes. Natural ventilation cannot clear cooking heat, smoke and grease on its own, so a kitchen needs mechanical exhaust above or beside the cooking range regardless of window size.
Why does opening placement matter as much as size?
Air moves when it has an inlet and an outlet. Openings on opposite or adjacent walls create cross-ventilation; a single large window on one wall moves far less air than its size suggests.