Curtain Thermal Performance Calculator
See how much solar heat a curtain or blind cuts on a given window — by orientation, glass and treatment. Get the watts blocked and an indicative cooling saving for Indian homes. Numbers are estimates.
Your window
Default peak solar of 700 W/m² suits a clear-sky Indian afternoon. A west window in May can push higher. These are indicative estimates — real gain depends on shading, dust, AC sizing and how long the sun strikes the glass.
Heat-gain reduction
0%
dim-out curtain on a west-facing window
Watts blocked
249 W
from 829 W bare
Heat still entering
580 W
Est. yearly saving
₹995
indicative cooling cost
Bare-window gain
829 W
Read this before you trust the number
Interior curtains reduce heat gain far less than exterior shading (a chajja, pergola, external blind or even a tree). Once sunlight passes through the glass, most of its energy is already inside the room — an interior curtain mainly re-radiates and convects it, so the real benefit is smaller than the surface percentage suggests. To genuinely beat the heat, shade the glass outside first, then layer curtains for comfort and glare. These figures are indicative estimates, not a measured energy audit.
Cool your rooms with DesignAI
DesignAI suggests shading, glass and curtain layers to cut heat and glare for your orientation and climate.
Related Guides — Deep-dive reading
Do Curtains Save Energy? Heat, AC and the Real Numbers (India 2026)
How much heat a window really gains, how much curtains and blinds cut it, the honest bill impact by orientation, and why outside shading still beats anything you hang indoors.
Window TreatmentsDesigning a Naturally Energy-Efficient Indian Home
Comfort first, gadgets last — passive design, orientation, insulation, ventilation and the climate wisdom that cuts Indian energy bills
SustainabilityEnergy-Efficient Facades in India: How the Building Skin Cuts Your Cooling, Heating & Lighting Bills
How a building facade drives cooling, heating and lighting energy in India, the three levers of solar-heat-gain control, insulation and daylighting, U-value, SHGC, VLT and WWR in plain terms, ECBC and Eco-Niwas expectations, and real Indian green buildings.
Building FacadesRelated Tools — You may also find these useful
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Estimate how much noise and echo heavy, full curtains will dampen — and where they help vs where they can't.
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Estimate how dark a room will actually get from a fabric, lining and fit — and why edge gaps matter most.
Estimator