MILLENNIUM® Windows and Doors — Double Pane Windows
MILLENNIUM® Windows and Doors are engineered for energy efficiency, long-term performance, and low maintenance — without forcing you to compromise on style. Every window we build is custom made to your exact specifications, from frame material and configuration to finish and design detail. Whether your project calls for modern contemporary aesthetics or faithful antique reproductions, MILLENNIUM® delivers custom windows and doors built to the highest standards of craftsmanship.
Our Window Series
A-Series — All-Aluminum Thermal Windows The A-Series features fully custom all-aluminum frames with thermally broken construction. Aluminum frames are exceptionally strong and virtually maintenance-free — no painting, staining, or sealing required. Because aluminum is highly conductive on its own, our A-Series frames incorporate an insulating polyamide thermal break between the interior and exterior aluminum profiles, which significantly reduces heat transfer through the frame and improves overall energy performance. Built to withstand demanding weather conditions, the A-Series is an ideal choice for both residential and commercial applications where durability and a clean, modern look are priorities.
Key Benefits:
- Architecturally modern aesthetic
- Exceptional structural strength
- Corrosion resistant
- Minimal maintenance
- Designed for harsh weather environments
Ideal for contemporary homes, coastal regions, and large glass openings.
M-Series — Aluminum Frame with Wood Interior Cladding The M-Series combines the structural strength and weather resistance of an aluminum exterior with the warmth and beauty of a natural wood interior. The aluminum exterior stands up to rain, UV exposure, and temperature extremes without warping or fading, while the wood-clad interior creates a rich, traditional look that complements virtually any interior style. This hybrid construction gives you the best of both worlds: minimal exterior maintenance with the authentic aesthetic of natural wood inside your home.
Key Benefits:
- Exterior aluminum protection
- Interior solid wood finish
- Excellent thermal performance
- Custom stains and paint finishes
- Low maintenance exterior
Perfect for luxury residences that demand both performance and natural warmth.
W-Series — Wood Frame with Aluminum Exterior Cladding The W-Series starts with a genuine wood frame — a time-tested material prized for its natural insulating properties and design versatility — and protects it with an aluminum exterior cladding. The aluminum shell shields the wood from moisture, wind, and weathering, dramatically extending the life of the window while retaining the warmth and character of real wood on the inside. The W-Series is the preferred choice for homeowners who want a traditional, wood-window look with significantly reduced upkeep.
Key Benefits:
- Traditional architectural appeal
- Custom millwork detailing
- High insulation value
- Long-lasting exterior protection
- Estate-level finish options
Ideal for custom homes, heritage projects, and high-end architectural builds.
Available Window Configurations
MILLENNIUM® double pane windows are available in a wide range of operating styles to suit any application:
- Double-Hung Windows
- Single-Hung Windows
- Casement Windows
- Sliding Windows
- Awning Windows
- Fixed/Picture Windows
- Bay and Bow Windows
- Special Shape Windows
- Fully Custom Designs
What Makes a Double Pane Window?
Double pane windows — also called insulating glass units (IGUs) — consist of two panes of glass separated by a precisely sized spacer and hermetically sealed to create a stable, insulating air space between them. In standard double pane windows this space is filled with air, but higher-performance units replace the air with an inert gas such as argon or krypton.
Argon gas is the most common upgrade fill. It is six times denser than air, which slows convection currents between the panes and reduces heat transfer. Argon-filled double pane windows can reduce U-factor values to the 0.25–0.35 range (compared to 0.90–1.00 for a single pane window) and are the recommended choice for most residential applications.
Krypton gas is approximately twelve times denser than air and provides even greater thermal resistance. It is typically used in triple-pane windows or where a narrower gap between panes is required. While krypton offers superior performance, it carries a higher cost premium and its benefit over argon in standard double pane applications is marginal for most climates.
Many MILLENNIUM® windows are also available with Low-E (low-emissivity) coatings — microscopically thin, optically transparent metallic layers applied to the glass surface. Low-E coatings work by reflecting long-wave infrared radiation (heat) back into the room in winter and deflecting solar heat away from the interior in summer, all while allowing natural visible light to pass through freely. According to the U.S. Department of Energy, windows manufactured with Low-E coatings typically reduce energy loss by 30–50% compared to uncoated glass.
Benefits of Double Pane Windows
Energy Savings The primary reason homeowners and builders choose double pane windows is the reduction in heating and cooling costs. Replacing single-pane windows with double pane, Low-E, argon-filled units typically yields 20–50% reductions in energy loss through the glazing, depending on climate, home size, and existing window condition. Windows and doors can account for a significant share of a building’s total heat loss, making them one of the highest-impact envelope upgrades available.
Improved Comfort — Eliminating Hot and Cold Spots Beyond the energy bill, double pane windows meaningfully improve interior comfort. Single-pane windows create cold radiant surfaces in winter and hot zones near the glass in summer, producing the uncomfortable “cold spots” and drafts familiar to most homeowners. By reducing heat transfer through the glass, double pane windows maintain a warmer interior glass surface in winter and a cooler one in summer, eliminating these problem areas and making the entire living space more consistently comfortable regardless of how hard the HVAC system is working.
UV Protection and Furnishing Preservation Low-E coatings block a significant portion of the sun’s ultraviolet and near-infrared radiation — the wavelengths responsible for fading fabrics, carpeting, wood flooring, and furnishings. This protection extends the life and color vibrancy of your interior finishes without noticeably reducing the amount of natural visible light entering the room.
Sound Attenuation An often overlooked benefit of double pane construction is its noise-dampening effect. The air or gas space between the panes acts as a buffer against airborne sound transmission, reducing the intrusion of traffic noise, aircraft, train lines, and neighborhood activity. This makes double pane windows especially valuable for homes or businesses located near busy roads, transit corridors, or in densely populated areas. Triple pane windows, for reference, can provide an additional 3–5 dB of noise reduction beyond double pane.
Reduced Condensation Because double pane windows maintain a warmer interior glass surface, condensation — the moisture that forms when warm interior air contacts a cold surface — is significantly reduced. This helps protect window frames, sills, and surrounding walls from moisture damage and mold over time.
Increased Property Value Energy-efficient windows are a recognized value-adding upgrade for residential and commercial properties alike. ENERGY STAR-certified windows may also qualify for federal tax credits and utility rebates depending on your location and the specific products selected.
A Note on Performance Ratings
When shopping for windows, look for products rated by the National Fenestration Rating Council (NFRC). Key metrics include:
- U-Factor: Measures how well the window insulates. Lower is better. Single pane windows typically rate 0.90–1.00; quality double pane units with Low-E and argon fill achieve 0.25–0.35.
- Solar Heat Gain Coefficient (SHGC): Measures how much solar heat passes through the glass. The ideal value depends on your climate — lower SHGC in cooling-dominated climates, higher in heating-dominated ones.
- Visible Transmittance (VT): The amount of visible light the window allows through.
ENERGY STAR certification confirms that a window meets the EPA’s minimum efficiency thresholds for your specific climate zone.
From modern contemporary to antique reproductions, MILLENNIUM® builds custom windows and doors to your exact vision. Contact us to discuss your project.