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In almost all buildings people value a strong connection to the outdoors, whether it’s a view through a window, natural daylight, or easy access to outdoor space on a nice day. Doors and windows provide those critical connections—the challenge is to have them do that without sacrificing energy efficiency or durability.

This category includes doors (both interior and exterior), windows, skylights, and curtainwall or storefront glazing systems. In addition to energy-efficient windows and doors, you’ll find revolving doors (they save a lot of energy by controlling air leakage) and solar cells embedded in glass to make building-integrated photovoltaics.

Exterior shading devices, such as awnings or shutters are covered under Exterior Specialties, and interior window treatments are under Furnishings. The louvers that are included here under Openings are those that are part of a glazing system, often fitting in between the two panes of a double-glazing system.

Door Options

Energy-efficient exterior doors are usually polyisocyanurate foam wrapped in metal or fiberglass. Insulating values of R-5 to R-7 are common in doors made that way. Storefront commercial door systems are not typically as energy efficient, although revolving doors help to reduce air leakage in tall buildings.

Interior doors are typically solid wood, molded hardboard, or plywood veneers over a hollow core. Since lauan plywood comes from poorly managed rainforest wood, it should be avoided. Molded hardboard is often made with some recycled content and pressed into shape, but most hardboard is made with unhealthy urea-formaldehyde binders. While solid wood is beautiful and a natural, minimally processed product, clear stock is becoming harder to get and may come from old-growth forests.

An increasing number of manufacturers are offering doors using wood from Forest Stewardship Council (FSC)-certified sources. Salvaged doors, or doors made from salvaged wood, can also be good choices.

Window Options

Since the early 1980s, the energy performance of typical windows has increased by more than 50 percent, the result of both improvements in glazing and in frame construction.

Double-glazed, low-e coating insulated glazing units (IGUs) are now standard in many parts of North America, although they are still described as “high-performance glazing.” Truly high-performance glazing systems, with a suspended clear film between the glass providing three layers of protection, are increasingly affordable, and becoming available in large units for commercial facades as well.

By careful selection of low-e coatings, windows can be “tuned” to optimize the performance of a structure—balancing heat loss, solar gain, and visible light transmission through the glass.

Use of an inert, low-conductivity gas in the space between layers of glazing is another way to improve thermal performance. Most low-e windows have argon gas fill. Some super-energy-efficient windows have krypton or a mix of argon and krypton between the glazing layers.

About window frame materials

Although standard for many years, aluminum windows are disappearing from most cold-climate markets. Vinyl frames are much better than aluminum in terms of thermal performance, but there are some environmental concerns associated with the production and eventual disposal of PVC (polyvinyl chloride). Vinyl windows vary greatly in quality. A particular weakness of vinyl windows is that vinyl expands considerably (more than wood or fiberglass) when heated by sunlight, and many consumers complain about weather-sealing problems over the life of the window due in part to this issue.

Wood windows are still the standard for energy efficiency. Vinyl or aluminum cladding adds value because of its low-maintenance qualities. Wood-window manufacturers are facing increasing difficulty in finding affordable, knot-free material from which to manufacture their product, and some are using finger-jointed material with an interior coating and exterior cladding. Other energy-efficient frame materials include fiberglass, with or without foam insulation in the hollow channels, and composites such as a combination of recycled vinyl and wood fibers.

All glass buildings are rarely the most efficient design; nor the best for daylighting—optimal window to wall ratios should be established with care.  However high-efficiency curtainwall systems are available. Storefront and curtainwall systems are all steel or aluminum, both of which conduct heat well so energy efficiency in those systems is all about effective thermal breaks in their design. These systems should also be designed to serve as effective pressure-equalized rainscreens to prevent rain penetration.

The edge seals and spacers that separate the layers of glass are another important element in any window assembly. These have to be energy efficient (providing an effective thermal break) but also very durable, as failure of this seal will cause condensation inside the window (fogging), and the loss of any low-conductivity gas fill.

In almost all buildings people value a strong connection to the outdoors, whether it’s a view through a window, natural daylight, or easy access to outdoor space on a nice day. Doors and windows provide those critical connections—the challenge is to have them do that without sacrificing energy efficiency or durability.

This category includes doors (both interior and exterior), windows, skylights, and curtainwall or storefront glazing systems. In addition to energy-efficient windows and doors, you’ll find revolving doors (they save a lot of energy by controlling air leakage) and solar cells embedded in glass to make building-integrated photovoltaics.

  • Clara Starrett Vinyl Windows
  • Clara Starrett Vinyl Windows
  • Mathews Brothers
  • Clara Starrett Vinyl Windows
    Mathews Brothers
    Mathews Brothers, which claims to be the oldest window manufacturer in the U.S., offers Clara Starrett vinyl windows, whose triple-pane, argon-filled series offer NFRC U-factor ratings of 0.17–0.20. Designated as “Most Efficient” by Energy Star, these windows feature tri-extruded frames with Air Cell insulated cores, warm-edge spacers, and fusion-welded frame and sash. They are available as double-hung, fixed, slider, casement, and awning styles and come with a 20-year limited warranty. Mathews Brothers manufacturers its own windows and insulated glazing units (IGUs) in Belfast, Maine.
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  • Cascadia Passive House Windows and Doors
  • Cascadia Passive House Windows and Doors
  • Cascadia Windows and Doors
  • Cascadia Passive House Windows and Doors
    Cascadia Windows and Doors
    Cascadia Windows & Doors offers a full line of high-performance fiberglass windows and doors, including some that meet Passive House standards. Triple-glazed versions of its windows have U-values as low as 0.14, with doors reaching U-values of 0.17. Window options include in-swing and out-swing casement, awning, and fixed; door options include in-swing and out-swing models with single or double doors. These windows and doors come with Hydro Tuff waterborne coatings that incorporate ceramic-based pigments for added durability and fade resistance, according to the company. They are available in nine standard colors, with custom colors also available. The company offers a limited warranty of 20 years on the frame and 10 years on the hardware and glazing.
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  • S.E.A.L. Window Systems
  • S.E.A.L. Window Systems
  • Wausau Window and Wall Systems
  • S.E.A.L. Window Systems
    Wausau Window and Wall Systems
    Wausau’s S.E.A.L. (sound, energy, air, and light) window system installs as a retrofit on the interior of existing weather-tight commercial windows or curtainwalls to improve their thermal and acoustic performance. They have a thin profile to fit within existing frames and can be accessed for cleaning via a lockable side-hinged mechanism. A variety of glazing options are available, including laminated glass, polycarbonate, dual-glazed, low-e coatings, and security glazing. Performance of the window assemblies will vary depending on existing glazing and frame. Venetian blinds that sit between the existing window and S.E.A.L. system can also be specified. Wausau recommends a sample S.E.A.L. window be installed for a “seasonal cycle” to ensure that the system will perform as intended. S.E.A.L. comes with a limited 10-year warranty.
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  • RavenWindow Thermochromic Glazing
  • RavenWindow Thermochromic Glazing
  • RavenBrick LLC
  • RavenWindow Thermochromic Glazing
    RavenBrick LLC
    RavenWindow is a filter that can be added by fabricators to standard insulated glass units (IGUs) and will tint at a certain temperature, reducing glare and solar heat gain coefficient (SHGC)—with projects seeing up to 30% energy savings, according to the company. RavenBrick can set the glass temperature at which the tinting occurs—anywhere from 40°F to 120°F, with the typical setpoint being 90°F. When tinted, the window’s energy performance can change dramatically, reducing SHGC by more than 20 points and dropping visible light transmittance (Tvis) from over 30% to 3.5%. The transition from clear to tinted occurs in less than 10 minutes, with the tinted area spreading across the window like an inkblot. The company offers a 10-year warranty through its fabricators, and the design life for the product is 30 years.
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  • EcoClad Composite Windows
  • EcoClad Composite Windows
  • Klearwall Industries
  • EcoClad Composite Windows
    Klearwall Industries
    Klearwall offers EcoClad, a line of composite windows and doors that are manufactured in Ireland. These windows have a powder-coated aluminum exterior, a PVC-encased polyurethane insulating core, and a wood frame interior. The windows can achieve whole-unit U-factors as low as 0.13 (R-7.5) and are available double- or triple-glazed with a krypton or argon gas fill.
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  • Groke Aluminum Entry Doors
  • Groke Aluminum Entry Doors
  • Sommer USA
  • Groke Aluminum Entry Doors
    Sommer USA
    Groke doors are all-aluminum, powder coated, and achieve a whole-unit U-factor that ranges from U-0.257 (R-3.9) down to U-0.13 (R-7.7). Doors are available in three thicknesses based on how much extruded polystyrene insulation they contain—0.94" (24mm), 2.52" (64mm), or 3.70" (94mm)—with triple glazing that comes standard on the upper two thicknesses. Models with 64mm of insulation have an overlay panel on the outer skin of the door, and the 90mm doors have overlay panels on both sides. All doors come with three-latch multipoint locking and most are rated class 4 in the air permeability test DIN 12207.
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  • Makrowin Wood Windows
  • Makrowin Wood Windows
  • European Architectural Supply, Inc.
  • Makrowin Wood Windows
    European Architectural Supply, Inc.
    Makrowin wood windows are made from European spruce, oak, and mahogany, and can be double- or triple- glazed. With aluminum cladding on the exterior, whole-window U-values range from 0.12 to 0.13 with a center of glass U-factor of 0.88. Wood certified by FSC is available upon request. The highest-performing Makrowin window, the MW88G2, meets the strict energy and air-tightness requirements of the Passivhaus Institut and uses cork to insulate the frame. The company claims these windows are the thinnest PHI-certified wood windows at 3.46 inches thick (88mm). In addition to tilt-turn windows, Makrowin also offers a variety of entry, lift-slide, and patio doors.
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  • Willmar Windows
  • Willmar Windows
  • Jeld-Wen - Canada
  • Willmar Windows
    Jeld-Wen - Canada
    Willmar Windows, part of the Jeld-Wen family, manufactures the vinyl Ener-smart 7000 (Es7000) line. Included in Willmar's selection are a number of double- and triple-glazed options available with Solar Gain and Solar Shield low-e coatings featuring warm-edge Intercept spacers, and argon fill. Unit U-factors are offered as low as 0.16.
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  • J.S. Benson Custom Wood Windows and Doors
  • J.S. Benson Custom Wood Windows and Doors
  • J. S. Benson Woodworking & Design, LLC
  • J.S. Benson Custom Wood Windows and Doors
    J. S. Benson Woodworking & Design, LLC
    J. S. Benson Woodworking & Design is a manufacturer of high-end, custom, true-divided-lite windows both for the renovation and new construction market, with FSC-certified wood available as an option. The company offers dual-sealed insulated units using clear annealed glass. Energy features include low-e coatings, argon-fill, and warm-edge insulated glass spacers.
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  • SageGlass Electronically Tintable Glazing
  • SageGlass Electronically Tintable Glazing
  • SAGE Electrochromics, Inc.
  • SageGlass Electronically Tintable Glazing
    SAGE Electrochromics, Inc.
    SAGE Electrochromics manufactures SageGlass, an electronically tintable exterior glazing that blocks solar heat gain while providing glare control and preserving views. SageGlass incorporates durable thin-film ceramic coatings and uses 0.28 W/ft2 to switch the glass from clear to tinted state and 0.1 W/ft2 to maintain a darkened state. Used with typical clear glass to fabricate an insulated unit, the tinting reduces the visible transmittance (Tvis) from 60% to 1%, while reducing the solar heat gain coefficient (SHGC) from 0.41 to 0.09. The company's triple-pane (Tvis 52% vs. 3%; SHGC 0.38 vs. 0.06), argon-filled and krypton-filled glazings have center-of-glass winter U-factors as low as 0.14 (R-7.1) and 0.12 (R-8.3), respectively. SageGlass can also come with a technology called LightZone, which enables one pane of glass to be tinted to different levels in three sections. SAGE is partnering with window, skylight, and curtainwall manufacturers to produce commercial and residential products that can help save energy while improving occupant comfort and control.
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  • Assa Abloy PoE Access Control Locks
  • Assa Abloy PoE Access Control Locks
  • Assa Abloy
  • Assa Abloy PoE Access Control Locks
    Assa Abloy
    Assa Abloy offers power-over-ethernet electronic access-control locks, including the SARGENT Profile Series v.S1, the SARGENT Passport 1000 P1, and the Corbin Russwin Access 700 PIP1. Ethernet data cables carry low-voltage electricity to power the lock as well as transmitting data to and from the devices using a facility’s already existing wired and wireless local area network (LAN). Each PoE door typically uses about one watt per door in standby mode, saving more than 150 kWh per year compared to a traditionally wired system. Ethernet power loads are low enough that a modest uninterruptable power supply (UPS) may be able to maintain electronic-access functionality in the case of a power outage.
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  • ERC 50 Renovation Façade
  • ERC 50 Renovation Façade
  • Schuco USA
  • ERC 50 Renovation Façade
    Schuco USA
    The ERC 50 Renovation Façade from Schüco is a retrofit façade system that can be installed on older, inefficient commercial buildings to improve energy efficiency, occupant comfort, and aesthetics. The ERC 50 incorporates an aluminum load-bearing framework, Schüco’s high-performance windows, exterior insulation, and cladding into a system that can be installed with minimal disturbance to building occupants. The ERC 50 is modular and uses EPDM gaskets rather than caulk, so it is relatively easy to replace damaged components. Schüco’s building-integrated photovoltaic panels can also be used in this system.
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  • Casagrande Woodworks Windows
  • Casagrande Woodworks Windows
  • Casagrande Woodworks
  • Casagrande Woodworks Windows
    Casagrande Woodworks
    Casagrande windows incorporate FSC-certified timber, Cardinal or Alpen Glass, Siegenia hardware, and Gutmann cladding.The Synergist model, made in the U.S., has achieved Passivhaus product certification through Germany's Passive House Institute and is certified with a whole-window U-value of 0.139 (R-value of 7.2).
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  • CaliPassiv Wooden Windows
  • CaliPassiv Wooden Windows
  • Wooden Window
  • CaliPassiv Wooden Windows
    Wooden Window
    The CaliPassiv aluminum-clad wooden window achieves Passivhaus product certification through Germany's Passive House Institute. The CaliPassiv line includes one operable and one fixed model. A whole-window U-factor of 0.137 translates to an R-value of 7.3.
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  • SunBeamer 100
  • SunBeamer 100
  • SunCentral Inc.
  • SunBeamer 100
    SunCentral Inc.
    SunCentral’s SunBeamer 100 tracks the sun throughout the day and uses lenses to direct sunlight into building interiors. The SunBeamer can be used in skylights or tubular skylights or in combination with the company’s SunLuminaire, SunShade, and SunSpandrel products. Using this system, sunlight is directed down the exterior of the building where reflectors in the company’s SunShade reflect and concentrate the light, focusing it into the SunSpandrel and into the building. The light then travels along the SunLuminaire, that has a reflective interior that can provide daylighting up to 50 feet into the building interior. The luminaires also contain sensors and LEDs that automatically adjust interior light levels based on available sunlight.
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