This glossary covers terms you'll see across our windows content, contractor quotes, manufacturer spec sheets, and incentive program documentation. Use it as a reference - we link key terms from across the site back to definitions here.
- U-Factor
- Measure of window insulation. Lower = better. ENERGY STAR requires U-Factor of 0.30 or less in most climates.
- SHGC (Solar Heat Gain Coefficient)
- Fraction of solar heat the window allows. Lower SHGC = less solar gain. Important in cooling-dominated climates.
- VT (Visible Transmittance)
- Fraction of visible light the window allows. Higher = brighter interior.
- Low-E Coating
- Microscopic metal oxide coating on glass that reflects infrared heat while passing visible light.
- Argon / Krypton Fill
- Inert gas filling between window panes. Improves insulation vs. air-filled. Krypton is better and more expensive.
- Double-Pane
- Two glass panes with gas-filled gap. Standard for modern replacement windows.
- Triple-Pane
- Three glass panes. Best insulation but heaviest and most expensive. Worth it in cold climates.
- ENERGY STAR Certified
- Federal certification meeting climate-zone-specific U-Factor and SHGC thresholds. Qualifies for 25C tax credit.
- Vinyl Windows
- Most common replacement material. Affordable, low-maintenance, 20-30 year lifespan.
- Fiberglass Windows
- More dimensionally stable than vinyl. Higher cost but longer lifespan and better paint adhesion.
- Wood Windows
- Traditional material. Best appearance, highest maintenance, longest history. Often clad in aluminum or vinyl exterior.
- Composite Windows
- Wood/fiber composite material. Combines wood appearance with synthetic durability.
- Aluminum Windows
- Lightweight, strong, but poor insulator unless thermally broken. Common in commercial settings.
- Double-Hung Window
- Most common style: two operable sashes that slide vertically. Both sashes typically tilt in for cleaning.
- Single-Hung
- Like double-hung but only the bottom sash operates. Less expensive.
- Casement
- Hinged at the side, opens outward with a crank. Best for ventilation and air-sealing.
- Awning
- Hinged at top, opens outward at bottom. Good for ventilation during rain.
- Slider
- Horizontally sliding sash. Common in modern construction.
- Bay / Bow Window
- Multi-panel window that projects outward from the wall. Bay = angular, Bow = curved.
- Impact-Resistant
- Windows tested to resist storm debris impact. Required in Florida HVHZ. Often qualify for insurance discounts.
- HVHZ (High Velocity Hurricane Zone)
- Miami-Dade and Broward counties. Strict impact-rating requirements for windows.
- WBDR (Wind-Borne Debris Region)
- Coastal areas requiring impact glazing or shutters under International Building Code.
- NOA (Notice of Acceptance)
- Florida product approval document required for compliance with HVHZ code.
- Insert (Pocket) Replacement
- New window installed inside the existing frame. Faster and cheaper than full-frame replacement.
- Full-Frame Replacement
- Removing existing window down to the rough opening and installing complete new unit. Required if frames are damaged.
- Title 24
- California's building energy code. Specifies window U-Factor and SHGC requirements.
- Section 25C Tax Credit
- Federal credit covering 30% of energy-efficient window cost, up to $600 per year.