July/August  2002


Things You Should Know When Selling Energy-Efficient Products to Customers
by Tom Smiley

Ultra™ Series windows from Milgard Windows are constructed of pultruded fiberglass and offer superior energy efficiency when paired with SunCoat™.

More and more homeowners are taking it upon themselves to become educated in energy conservation. In order to assist your customers in the purchase of energy-efficient windows, be it replacement windows or windows for a new home, it is important that you have a solid understanding of the standards, developments and future of energy-efficiency in regards to residential- and light-commercial window applications. 

Knowing the basics of window energy efficiency will go a long way to making a sale, reinforce your commitment to your customer’s well-being and establish you as a knowledgeable resource. Here are a few questions your customers might be asking:

Why should I care about energy-efficiency? 
Knowledgeable homeowners can cut their annual heating and cooling costs by making smart purchases. And contractors, while not involved in their clients’ monthly energy bills, can provide a valuable service to their clients by educating them on the benefits of energy-efficient building options like windows.

As the energy crisis in the Southwest continues, John Offner, owner of Thermaguard Construction in California, is seeing more and more concerned homeowners coming through his doors. With local temperatures rising well into the 100s, the first thing his customers ask about in windows is energy-conservation properties.

Norvan Huff, owner of Whitey’s Home Improvement and Cimarron Manufacturing & Supply Co. in Colorado, points out that while the amount of energy lost daily through inefficient windows may seem miniscule, over time it adds up to some significant bills. The Milgard dealer and his team reinforce the concept to their customers that making the investment in energy-efficient windows now will save them money in the long run.

Consumer-Oriented Programs 
Energy Star® is a joint program of the U.S. Department of Energy (DOE) and the Environmental Protection Agency (EPA). The Energy Star designation is given to products meeting certain energy performance criteria. Considering the energy-efficient performance of windows and skylights varies by climate, product recommendations are given for three U.S. climate zones: Northern, Central and Southern. Products meeting these requirements are stickered with the Energy-Star label.

The National Fenestration Rating Council (NFRC) has developed a window energy-rating system based on the whole product performance: glass and frame. The NFRC provides a reliable way to determine the window energy properties and compare products. The NFRC label appears on all products certified to the NFRC standards and on all windows, doors and skylight products which are part of the Energy-Star program. At this time, NFRC labels on window units give ratings for U-factor, SHGC, and visible transmittance (VT). Air leakage is another rating that is sometimes included on the NFRC label, though it is not required. (See related article in June 2002 SHELTER on pg. 34.)

How has energy-efficiency of windows improved? 
Window technology has come a long way since the days of single-pane aluminum frame windows. In recent years, manufacturers have introduced a wide range of energy-efficient window products to the building industry—from insulating glass units and thermal spacers to tinted glass and low-emissivity coatings. 

Most manufacturers promote energy efficiency through their involvement with the Energy-Star program. Some window manufacturers specialize in niche products that increase energy efficiency, like providing extremely high U-factors. These are great products for consumers, but generally come with a high price tag.

Our company, for example, offers a full line of frame and glass types, coatings and manufacturing processes, from aluminum, vinyl and fiberglass options in the South to vinyl and fiberglass options in the North.

Classic Series™ Vinyl Windows from Milgard keep the winter’s cold from penetrating this home’s interior.

Framing Options
A variety of framing options exist, including vinyl, wood, fiberglass and aluminum. Vinyl windows carry low U-values, offering reliable energy efficiency. Some companies manufacture vinyl frames made of multiple hollow chambers. The greater the number of chambers, the more stable the frame. In addition to providing stability, the innovative chambered construction also increases energy efficiency. The honeycomb-like chambers act as additional insulation, lowering heating and air conditioning costs while reducing outside noise.

The primary ingredient used in creating vinyl today is polyvinyl chloride (PVC). PVC has proven to withstand harsh elements such as extreme temperatures and weather conditions, corrosion and rust. In addition, vinyl frames don’t warp or crack. They require little maintenance and are available in a wide range of styles and shapes. Because of their durability and energy-efficient nature, vinyl windows are a very popular option in the home-building industry.

Wood frames also carry low U-values, and they are not affected by extreme temperatures. On the other hand, they also require some maintenance and regular painting. If wood frames are not properly protected from moisture, they can warp and crack. Our company offers a special composite frame constructed of fiberglass on the outside and vertical grain Douglas fir on the inside. In addition to their thermal benefits, fiberglass frames don’t warp, shrink, swell or rot. They’re extremely durable, are available in a variety of colors and can be painted.

Aluminum frames are often used in warmer climates where maintaining heat inside a home is less of an issue. Aluminum frequently causes conductive heat loss and condensation. However, by adding spacers or special glazing options, the thermal resistance of aluminum windows can be greatly improved. 

Glazing Options
Low-emissivity (low-E) glass is fast becoming the product of choice among builders, remodelers and consumers looking for new construction and replacement windows. Emissivity measures the amount of heat that is emitted from a window. The lower the level of emissivity, the more efficient the window. Emissivity levels generally range from 0 to 1.

Low-E windows have a clear, microscopically thin coating on one side of the glass. This special coating, made of silver and metal oxide, is placed on window panes to reduce the amount of heat they give off through radiation. Offner describes low-E to his clients as doing the same thing a screen would, but without the darkening effect.

Energy loss not only occurs through the window pane, but also around the edges of a window. Because the thermal resistance around the edge is lower than that in the center of a window, heat can escape and cause condensation. To address these problems, manufacturers have developed “warm-edge technology.” In a multiple-pane window or insulating glass unit, the layers of glass are held apart by spacers. Traditionally, spacers have been constructed of four sides of aluminum, but aluminum conducts heat. Manufacturers have now developed thermally improved spacers, known as “warm edge” spacers. One of these developments is a thin U-shaped spacer constructed of steel. Steel transfers less heat than aluminum, thereby increasing energy efficiency. The U-spacer’s unique shape also absorbs much of the glass movement that can occur when temperatures fluctuate, reducing the possibility of seal failure and glass breakage.

Installation Factors 
A window truly is only as good as its installation. A frame that does not fit its opening means heat and cold can pass through, wasting energy and money. 

The American Architectural Manufacturers Association (AAMA) has instituted its Certified InstallationMaster™ program, providing training to window, door and skylight installers in an effort to avoid costly callbacks. You can learn more about the AAMA Certified InstallationMaster program by visiting

By being an educated dealer, you can help your customers answer important questions: Which frame and glass options are best for my home? What types of windows perform best in warm climates? Which windows save the most energy? How do my desires for lighting, heating, shading and aesthetics affect my options? Addressing these questions before choosing a window will save homeowners energy and money that otherwise would have been lost to unnecessary heating and cooling costs. 

                                 What is Energy Star?

                                                             ENERGY STAR-LOGO  

In the Northern zone, where heating is mostly the concern, a window’s glass must have a U-factor of .35 or less. In the Southern zone, where cooling is mostly the concern, a window’s glass must have a U-factor of .75 or less, and a solar heat gain co-efficient (SHGC) of .40 or less. In the Central zone, where both heating and cooling are issues, a window’s glass must have a U-factor of .40 or less, with an SHGC of .55 or less. 

The U-value is a measure of how much heat escapes through a window unit. The lower the U-value, the more efficient the window. U-values generally range from .1 to .9, with .1 being the most efficient. Ultraviolet light also has the tendency to fade furniture and carpet. When determining which window is best for a particular application, look to a window’s U-value first.

The SHGC measures the sun-shielding properties of a window, particularly important in warm climates where a cool indoor temperature is desired. The lower the SHGC rating, the better the product will protect from solar heat entering a home. In Southern regions, glass products with lower solar heat gain ratings help keep annual cooling costs low. When looking at SHGC ratings, clear-over-clear insulating glass typically carries a rating around .80, whereas tint-over-clear insulating glass has a rating of approximately .45. Tinted glass offers a wide range of benefits. It absorbs heat, thereby minimizing solar heat gain, reduces interior damage caused by harmful ultraviolet rays, and adds an element of privacy by decreasing visibility to a home’s interior.


Tom Smiley is a marketing specialist for Milgard Windows of Tacoma, Wash.


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