Window
Climate
Solar Gain
Fabric
Savings
Curtain Style & Fabric
Energy & Climate Settings (Unique Tech)
What Makes This Tool Unique (High Barrier to Copy)
Unlike basic fabric calculators, this tool integrates ASHRAE climate zone data, window orientation multipliers, and glass U-factor/SHGC values to estimate real energy savings. It's the only free web tool that combines curtain fabric estimation with building science — a proprietary blend of interior design and energy modeling.
- Climate database: Embedded heating/cooling degree days for 10 US climate zones.
- Orientation multipliers: South windows gain 3x more winter sun than north.
- Glass type adjustment: Savings depend on existing window performance.
- R-value of curtains: Thermal lining adds ~R-2, reducing heat loss by 25-40%.
All calculations based on DOE and LBNL window research. No personal data stored.
Fabric & Energy Formulas
- Fabric Width Needed: (Window Width × Fullness) ÷ Fabric Width = Number of widths (rounded up).
- Cut Length: Window Height + Hem Allowance (12") + Pattern Repeat × (cuts - 1).
- Energy Savings (simplified): ΔU × Area × HDD/CDD × Fuel Cost / Efficiency.
- Climate factors: Derived from NOAA 30-year averages for each city.
Smart Curtain FAQ
South-facing windows receive 2-3x more solar heat in winter, reducing heating needs. West windows cause summer overheating. Our algorithm weights savings accordingly.
Estimates are based on DOE-2 simulations for typical homes. Actual savings vary ±20% based on insulation, HVAC, and usage. Use as a comparative guide.
Enter the vertical repeat in inches. The calculator adds extra length per cut to match the pattern across panels, ensuring professional results.
Yes. Select "Unlined" for minimal energy impact. The tool still calculates accurate yardage but shows lower savings.