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    What Does "U-Factor" Mean?

    Last updated 3 years ago

    To a consumer shopping for replacement windows, energy-efficiency labels can be confusing. These labels display several numbers: solar heat gain coefficient, visible transmittance, air leakage, condensation resistance, and U-Factor. When you are selecting windows for your home, you should make sure that the products you purchase have the U-Factor appropriate for your home’s insulation needs. The U-Factor measures the total amount of heat energy that flows through the window by these three processes:


    Conduction is the transfer of heat through adjacent particles in solid material. Highly conductive materials will heat up faster than less conductive materials. Thus, a window assembly that conducts heat well will not protect your home from temperature fluctuations. Metal frames conduct more heat than wood, and thus tend to have higher overall U-Factors.


    Convection is the transfer of heat by airflow. As the temperature of the window affects the air around it, cold air will sink and hot air will rise. This air motion is called convection current, and it can cause drafts of warm or cold air inside the room. Many double- and triple-paned windows, such as those by Simonton, have a layer of inert gas between the glass panes that reduces convection heat transfer and lowers the window’s U-Factor.  

    Thermal Radiation

    Thermal radiation does not need airflow to transfer heat from one object to another. A hot windowpane will emit thermal radiation, which will heat objects and people in the room. A cold window will absorb the heat emitted by other objects inside the room. Windows with higher U-Factors will absorb thermal radiation from the sun in the summer and heat up the interior of the house, while in winter they will allow the thermal radiation generated by your body heat and home heating system to escape.

    The window technicians at Five Star Windows can determine the correct U-Factor for your home’s replacement windows to maximize energy efficiency all year round. Call us at (408) 385-9867 to find out more about our new window installation services.

    The Steps Involved with Replacement Window Installation

    Last updated 3 years ago

    Once you have selected the replacement windows that fit your aesthetic and your budget, the next step is installation. Always make sure that your windows are sealed and weatherproofed correctly, so that your home does not suffer wind or rain damage. To ensure that your replacement windows are installed properly, hire a contractor for your window project. A window professional has experience with every step of the process. Your window contractor will:

    Remove the Old Window Components

    The type of window installation determines how complicated the removal process will be. Unlike new full-frame windows, which require the contractor to cut out the entire frame, replacements are relatively simple. A window replacement is installed inside the existing frame, so your contractor will not need to spend a lot of time removing the old components.

    Measure the Space

    Once the old window is removed, the contractor will measure the rough opening to determine the proper size for your replacement window. Measurement is easier with the old window components gone, which is why this step comes after removal. Your window contractor knows how to calculate the proper measurement allowances for shims and insulation. 

    Install and Align the Window

    Installation requires much more than merely putting the window into place and securing it. The contractor will install flashing to direct rain away from the home, and insulation to prevent heat loss.  Then, the window must be shimmed to ensure it is level, and finally it must be squared off. These delicate processes go faster with experience, so a professional window installer can finish much quicker than an inexperienced layman.

    If you are considering retrofitting or replacing the windows in your home, contact Five Star Windows today. We offer complete installation of windows and doors. Our professionals can help you select the right window materials and design for your home. To learn more, call us today at (408) 385-9867.

    A Look at Milgard SunCoat and SunCoatMAX Low-E Glass

    Last updated 3 years ago

    Milgard is proud to offer SunCoat and SunCoatMAX low-E glass to customers. This glass uses specialized coatings to minimize energy waste and lower the cost of your utility bills. Read on to learn even more about what these Milgard coatings can bring to your home.

    Subtle Applications

    Milgard’s glass coatings are one of simplest way to improve the energy efficiency of your home, especially when compared to the alternatives. Sun screens are bulky and can detract from the beauty of your windows. You can also shade your home with awnings, but adding these covers to your home is complex and expensive. Thankfully, Milgard’s SunCoat and SunCoatMAX low-E glass coatings are microscopically thin.

    Sustainable Performanc

    Solar heat can cause big problems for your home’s interior. The warmth carried by sunlight travels through your windows, increases indoor temperature, and forces your HVAC appliance to work harder, wasting energy. Thankfully, Milgard SunCoat and SunCoatMAX low-E glass can protect your household from escalating heat—these heat-deflecting coatings boast an impressively efficient solar heat gain coefficient. Milgard’s signature windows can also assist your home by reducing household heat transfer during the winter. Similar to summer heat, heat transfer during the winter forces your heater to work harder than normal. The most cost-effective way to eliminate this energy waste is through reliable Milgard products.

    UV Protection

    Sunlight contains invisible rays of energy that are known as “ultra-violet” light. Ultra-violet (UV) light is so powerful that constant exposure can actually change the color of your floors and furniture.  However, this color change can be prevented with high-quality window glass. Products are equipped with Milgard’s SunCoatMAX® low-E glass prevents these powerful rays from infiltrating your home. In fact, the right glass can reflect up to 99.9% of UV light.

    Contact Five Star Windows today if you have more questions about low-E glass. We are experienced installers of Milgard products, so you can have these coated windows installed quickly and conveniently. Get in touch with us at (408) 385-9867 to schedule your free estimate.

    What to Expect When Having Milgard Replacement Windows Installed

    Last updated 3 years ago

    Your windows are an important aesthetic and practical component of your home. A new set of windows can greatly improve your home’s curb appeal, and new energy-efficient materials can insulate your home and save you money on your utilities each month.

    When you select Milgard windows and have them installed by a Milgard Certified Dealer, you can expect excellent customer service each step of the way, from the window selection process to the post-installation clean-up. Watch this video to find out more about the window installation process.

    For your window replacement project, contact Five Star Windows. We professionally install high-quality windows and doors all around the San Jose area. Call us today at (408) 385-9867 to discuss your new window options.

    "Very happy with the new windows and my experience with Five Star."

    Last updated 3 years ago

    • on
    • Very happy with the new windows and my experience with Five Star. The windows were ready on time and I am very happy with the price and the quality of the work.

      Phoenix, AZ

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