Choosing Windows

Not All Replacement Window Projects Are Equal

One of the most common reasons that homeowners replace windows is for improved aesthetic appeal. But there is a lot more to look for when choosing windows for an installation project than appearances. To get the most value, safety, comfort, and energy performance from a window replacement project, it is important to choose the appropriate product and follow industry best practices during installation.

Choosing the Appropriate Replacement Window

Many contractors sell replacement windows, especially vinyl windows, on price alone. It is surprisingly inexpensive to assemble a basic vinyl window – common smaller size windows often wholesale for less than $50 apiece! However, although the cheapies will look pretty similar to the name brands from the street, they won’t perform nearly as well, nor will they necessarily provide crucial features.

Windows & Fire Safety

Fire safety is perhaps the most important aspect of a window purchase. Building Code requirements regarding egress from a building in case of a fire are both stricter and more universally enforced than they have been in the past. Many bedrooms have double hung windows which often don’t have large enough openings to meet fire code egress requirements – meaning that some people, particularly children and senior citizens, may not be able to escape in case of a fire. Replacing these double hung windows with casement or awning windows, which allow the entire window area to open, typically bring the windows into code compliance. However, replacing double hung windows in bedrooms with “like for like” often will not meet current code. Also, many towns require tempered glass to reduce the likelihood of the window shattering in a fire. This is especially common in the Western U.S. where forest fires are more common and widespread. Don’t ignore fire safety, lest your project get burned by a code official when the project is inspected.

Glass Breakage

Glass breakage requirements are also mandated in most areas. Windows in bathrooms are required to be tempered in most cases due to the likelihood of slipping and falling into a window. Windows with low sill heights, windows located near high traffic areas, sliding glass doors, and French doors are all usually required to have tempered safety glass.

Window Energy Performance

Energy performance is a major reason many window projects are undertaken, but homeowners and contractors frequently fail to verify the energy performance of windows they install.

The National Fenestration Rating Council (NFRC) verifies the energy performance of windows across a variety of criteria as depicted in the image above. Many window salespeople tout the value of their projects, including the availability of a $500 federal tax credit for window replacement. However, if the windows don’t meet Energy Star requirements – or can’t be proven to meet requirements in the case of some custom windows –  the project is rendered ineligible.  You should insist that any potential installer provide the NFRC rating for the windows that will be used in the project, and check carefully to ensure all products are eligible – Energy Star window requirements vary by climate within the US. Most “tilt-pack” windows, which tilt inward for easy cleaning, are not eligible.

Livability & Comfort 

Apart from actual energy performance, NFRC ratings are very helpful in determining which windows will most improve the livability of a home. Almost universally, a window with a low U-factor and low air leakage will help retain heat within the home during winter. However, based on orientation, home design, and intended use, choosing windows with unique U-factor, Solar Heat Gain Coefficient, and Visible Light Transmission characteristics can enhance the outcome. For example, if your home faces west over a beautiful view and has lots of windows, chances are it overheats on summer afternoons. Among other improvements, choosing a window with low solar heat gain will minimize overheating and save on air conditioning. If your home was designed to utilize passive solar heating, or has lots of south-facing glass in a cold climate, utilizing a window with high solar heat gain can save a lot of energy by using the sun, rather than the furnace, to heat the home. If a workshop, studio, or office is on the north side of the house, a window with high Visible Light Transmission will help maximize the northern light’s excellent natural light characteristics and reduce or eliminate the need for electric lighting during the day. If the TV sits adjacent to an east-facing window, a low VLT window will reduce glare. Work with an experienced window installer who will consider the design and use of the home when selecting products.

Window Durability

It is common to see dual pane windows with fog or condensation stuck between the panes, or windows that don’t open or close properly due to failure of the mechanism or hardware. Ensure that the window you choose carries a warranty in line with industry standards – 5 years should be considered a minimum. Also be sure to read the fine print on your warranty.

Proper Window Installation

Choosing the best window isn’t worth much if the installation is lacking. The energy efficiency gains from a high quality dual pane window can be totally offset if drafts occur around the window. Make sure your installer thoroughly caulks the windows during installation. When trim is removed and the rough framing is exposed, be sure that your installer uses low-expansion foam sealant to seal the gaps around the window rough opening. Installers have traditionally used fiberglass, which will not prevent draftiness around the window. Fastener systems between the window and framing are critical, especially in areas prone to earthquakes or high winds. I have seen window projects have permits withheld pending a fastener schedule in the San Francisco Bay Area. Ensure that your installer is properly licensed and insured, and familiar with local code requirements and “gotchas”. Window installers should provide a warranty on their own workmanship, in case installation issues aren’t apparent until the window has been through the seasons. One year of workmanship warranty is a minimum for window projects.

Ventilation & Combustion Appliance Safety

Windows often greatly reduce the draftiness of a home, but one consequence of this benefit is that both occupants of the home as well as gas appliances may have been relying on the draftiness of those windows for healthy breathing or combustion air. Homes undergoing a window replacement project should undergo Blower Door Testing and Combustion Appliance Safety Testing both before and after the project takes place. Blower Door Testing will allow the reduction in draftiness and the improvement in energy efficiency to be quantified, as well as provide a frame of reference for whether supplemental ventilation might be needed to ensure adequate air circulation in the home. For more information on airtightness and ventilation, see “seal tight and ventilate right”. If combustion appliances are present in the home, they could have underlying safety problems, such as an obstructed flue pipe, cracked furnace heat exchanger, or inadequate Combustion Ventilation Air (CVA). Any of these safety issues could go unnoticed before window replacement, but be lethal afterwards.

Installed Right the First Time

Window replacement is one of the most expensive and complex projects that will ever take place in your home, and it is critical to follow the permitting process closely to limit your liability and ensure the project meets the often complex code requirements. To ensure a smooth process and top notch results, make sure the following criteria are met:

  • Thoughtful window selection
  • Attentive and professional installation
  • Pre- and post-project safety testing

As with most other energy-related projects, a home performance contractor, such as Advanced Home Energy in Richmond, CA, is usually one of the most capable installers. A home performance contractor will be able to understand how the windows function in the context of the whole house, and take the necessary steps throughout the project to ensure a fantastic end result.


Copyright September 2014 by Advanced Home Energy

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