By John Dybsky
One of the ways construction professionals can set their business apart is by recommending energy-efficient products to home and building owners. Even more beneficial than the potential savings these products can provide is a contractor who understands how energy-efficient materials coexist with other building components.
Low emissivity (Low-E) windows are energy-efficient windows that account for 90 percent of all new installations, according to the National Association of Home Builders. These windows are quickly becoming the standard with the federal government providing tax incentives and both the Environmental Protection Agency (EPA) and U.S. Department of Energy developing energy-performance criteria for window specifications. In multifamily buildings, the benefits of switching to Low-E can result in between $126 to $465 in utilities savings, according to the EPA.
Low-E windows typically contain two insulating glass units separated by a space. Argon or another inert gas is then contained in the sealed space between the two panes of glass. The term Low-E comes from a low emissivity coating applied to one pane of glass. This coating has two purposes:
- Reflecting out the sun’s short wave infrared energy in the summer; and
- Keeping in the home’s long wave infrared energy in the winter.
Bottom line, these windows have plenty of benefits for home and building owners, making them energy efficient in the summer and winter.
However, the same qualities that make these windows attractive to homeowners are also causing significant damage to some types of exterior siding.
Over time, as the argon gas permeates the window’s seal, the center of the panes are forced inward. The extra reflectivity, combined with concavity in the glass, turns the window into a powerful mirror. This concentrates sunlight, creating a direct ray of heat onto the siding of adjacent houses that can range from 160 to 200 degrees F. If a home is clad in vinyl siding, the heat caused by the windows can be sufficient to create irreversible buckling and distortion with extended exposure.
Most instances of vinyl siding distortion occur in the inside corner of a home or on the opposite wall of a nearby home. Homeowners in more than 16 states have reported melted siding due to these windows, and unfortunately for proprietors, the damages aren’t covered in vinyl siding warranties, according to the Vinyl Siding Institute.
Since replacing the siding will only lead to more melting, and the benefits of Low-E windows are so numerous, contractors are turning to different siding materials for homes that use or are near these windows.
Frequent alternatives to vinyl include wood and fiber cement siding. However, the windows have potentially devastating effects on wood siding as well, causing four house fires, according to an investigation from the Consumer Product Safety Commission.
As a result, many builders are recommending fiber cement siding as a siding material that will withstand the heat reflected from Low-E windows. Fiber cement siding is non-combustible and non-ignitable, meaning it won’t distort at the high temperatures of direct heat. While vinyl starts distorting at 165 degrees Fahrenheit, fiber cement can stand up to 2,500 degrees without softening or distorting.
As energy-efficiency becomes the standard, construction experts must consider accompanying materials that can play nicely with products such as Low-E windows.
John Dybsky is the Senior Marketing Manager at James Hardie Building Products, where he currently oversees the development and implementation of new marketing strategy. He has an MBA in Marketing from the University of St. Thomas, and 30 years of progressive experience in the building industry.