Window Calculator

Window Heat Gain Calculator

See how much solar heat pours into a room through its windows — and the AC load it adds. Set the area, orientation, glass and shading. West windows are usually the worst. Indicative India 2026 figures; confirm with a full load calc.

Your window

Window glass area (sq ft)

Orientation (which way it faces)

Glass type (SHGC)

External shading

City solar intensity

Q = area (m²) × peak irradiance (W/m²) × city factor × SHGC × shading factor. West afternoon sun is the harshest aspect in most Indian cities.

Peak solar heat gain

0 W

about 0.19 ton of extra AC load · 3.4 kWh/day

Daily heat

3.4 kWh

~5 strong-sun hrs

AC load added

0.19 TR

1 TR = 3517 W

Glass SHGC

0.82

lower lets in less heat

Heat cut

vs bare clear glass

Moderate load — a ceiling fan plus a modest AC will cope.

Same window, each orientation (W)

Your aspect is highlighted. West typically tops the chart.

Design windows that stay cool

DesignAI picks glass, shading and orientation to cut solar heat for your room and climate.

Use in DesignAI

Go deeper

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