Home Ventilation Score Calculator
Enter your openable window area, floor area, window layout and any fan / stack assist. Get a natural-ventilation score from 0–100, the rating, the single limiting factor and how to fix it. Indicative India 2026, benchmarked to the NBC ~10% openable rule.
Your room
Openable area is 12.0% of floor (meets the NBC ~10% guideline of 15 sq ft). Layout is the biggest lever — opposite walls beat single-sided several times over.
Ventilation score · Good
0 / 100
Natural airflow rating for this room
Rating
Good
Openable / floor
12.0%
NBC needs ~10%
NBC ~10% rule
Pass
15 sq ft target
Cross-flow factor
1.00×
Straight through-draught — ideal.
Main limiting factor
Well balanced — fine-tune opening placement
What builds the score
How to raise the score
- •Keep windows shaded and screened — fly-screens cut airflow ~15%, so size openings a little larger.
Indicative India 2026 model, benchmarked to the NBC ~10%-of-floor openable-area guideline. Real airflow also depends on wind speed, opening placement, partitions and screens — treat the score as a relative guide, not a measured value.
Design rooms that breathe
DesignAI places windows for cross-flow — sizing openings to your room, climate zone and layout.
Related Guides — Deep-dive reading
Window Design for Cross Ventilation (India): Inlet, Outlet and the Path of the Breeze
How to size, place and choose windows so a breeze actually crosses the room, windward inlet to leeward outlet, with the right window types and a clear flow path.
Windows & GlazingPassive Cooling Through Windows (India): Cool a Home Without the AC
How a window's operable area, cross and stack ventilation, night purge, external shading and low-SHGC glass keep an Indian room comfortable without air conditioning.
Windows & GlazingUnderstanding Wind Analysis for a Comfortable Home
How to read your site's breeze and design openings that keep an Indian home naturally cool — long before you switch on an air-conditioner.
Site PlanningRelated Tools — You may also find these useful
Window Quantity Calculator
Estimate how many windows your home needs for NBC daylight and ventilation norms.
Window ToolWindow Size Calculator
Get the right window size, glazing area and openable area for any room using NBC daylight rules.
Window ToolCross-Ventilation Analyzer
Estimate airflow and air changes per hour (ACH) from room size, window areas, layout, and local wind — with NBC 2016 Part 8 compliance check.
Ventilation Calculator