Window Types & Technology — Improving Energy Efficiency
Windows are an essential component of a home’s thermal envelope, protecting its inhabitants from the elements and allowing natural light and ventilation. However, energy inefficient windows can also be a significant source of energy loss, affecting the home’s overall energy efficiency. Many design features and technologies make windows more energy efficient and improve their durability, aesthetics, and functionality. In this article, we’ll explore different window types and technologies to consider when selecting new windows.
Frames and Sash
The frame material plays a crucial role in determining the thermal resistance and energy efficiency of a window. Various materials have different advantages and disadvantages, and some are more energy-efficient than others.
Aluminum or Metal Frames
Metal or aluminum window frames are lightweight, strong, and require minimal maintenance. However, they are poor insulating materials because they conduct heat rapidly. To improve their insulation properties, they should have a thermal break – an insulating plastic strip placed between the frame and inside and outside the sash.
Composite window frames consist of composite wood products, such as particleboard and laminated strand lumber, and some are mixed with polymer plastics. They have similar or better thermal and structural properties as conventional wood, and they are more moisture and decay resistant.
Fiberglass window frames are dimensionally stable and have air cavities that can be filled with insulation, providing superior thermal performance compared to wood or uninsulated vinyl.
Vinyl window frames are made of polyvinyl chloride (PVC) with ultraviolet light (UV) stabilizers to keep sunlight from breaking down the material. They don’t require painting and have good moisture resistance. The hollow cavities of vinyl frames can be filled with insulation, making them thermally superior to standard vinyl and wood frames.
Wood window frames insulate well, but they require regular maintenance. Aluminum or vinyl cladding can reduce maintenance requirements. Due to the conditions of the desert, we typically do not recommend wood frames to homeowners in our region.
Glazing or Glass
The glazing or glass is the most critical factor in determining a window’s energy efficiency. Based on various window design factors, such as orientation, climate, and building design, you may want to choose different types of glazing for different windows throughout your home.
Insulated Glazing Units (IGUs)
Virtually all new efficient buildings use double or triple glazed units with an insulating air space to reduce heat loss. The properties of the IGUs depend on the type of glass, coatings, gas fill, and spacers used between the panes.
Low-Emissivity (Low-E) Coatings
Low-e coatings on glass control heat transfer within the insulated glazing. Windows manufactured with low-e coatings typically cost more than regular windows, but they reduce energy loss by as much as 30% to 50%.
Spectrally Selective Coatings
Spectrally selective coatings filter out the sun’s non-visible infrared radiation while allowing the full amount of daylight to pass through. They are suitable for climates where cooling loads dominate.
Gas Fills and Spacers
Argon or krypton gas is filled in the space between glazing layers to minimize heat transfer between the interior and exterior of the window. Spacers with associated sealants keep the layers of glazing at the correct distance apart and prevent moisture and gas leaks.
To assess and compare the overall window properties, look for an NFRC or National Fenestration Rating Council label. The label provides information about U-factor, solar heat gain coefficient, visible transmittance, air leakage, and condensation resistance. By considering the frame materials, glazing, gas fills, and spacers, you can select the most energy-efficient windows that suit your needs, climate, and budget.
In summary, windows are a significant contributor to a home’s energy efficiency. By selecting energy-efficient windows, you can save money on your energy bills while also reducing your carbon footprint and contributing to a more sustainable future.
Selecting new windows for your home can be a great investment in your home’s overall value and comfort, and it’s important to work with a qualified professional to ensure that you choose the right type of window for your specific needs and preferences. Synergetic Home is here to serve you.