Energy Crisis:

Why choose deregulation as the only scapegoat? SwissShade's president offers his own view concerning some of the reasons behind the crisis.

Contents:

Understanding Energy-Efficient Windows: How today's high-tech windows work and what to look for when making your next purchase. Excellent and all encompassing article by Paul Fisette, the director of the Building materials Technology and Management Program at the University of Massachusetts.

Link to EarthPulse: How can you make a difference? A listing of resources and a forum at: http://www.nationalgeographic.com/ngm/0103/earthpulse/

Energy Efficient Consumer Products: http://www.energystar.gov/

Learn about renewable energy, check out the Green Power Network: http://www.eren.doe.gov

Energy Crisis: Why choose deregulation as the only scapegoat?

It strikes me that most explanations to the present energy crisis get stuck in the deregulation department. I have yet to read an article about the other and equally responsible culprit in this crisis: MAN, the often thoughtless user of all this energy.

One of the very obvious and often forgotten reason for the present energy crisis is the increasing amount of energy we are spending on heating and cooling. Being in the window business, it amazes me that the window sizes in modern homes are getting larger and larger while using windows and doors which are technically outdated and substandard in insulation values.

The native American Indians in the South West had a superb understanding of the need for shading, insulation and placement of openings. There was no electricity available to cool or heat their dwellings. But these early and energy conscious people made do with what they had and if any one ever has a chance to enter an old adobe building during the hottest time of the day, one will be surprised as to the comfortable temperature inside such a dwelling! And during a 24 hour period, one will be surprised how even the temperature is. Builders throughout the country are putting up homes with large amounts of glass in order to ride this "have to have a view" fashion. At the same time they try to save money by choosing the cheapest available glazing.

Large picture windows with low insulation values, facing south and not being shaded will use an enormous amount of energy for cooling. The same goes for heating since the placement of windows is based on the best view rather then on energy efficiency. In Tucson, AZ, I hear from people paying between $ 600 and $ 700 per month to cool a single residence. This over usage should be penalized not unlike the system California used to regulate the water usage during the drought. There is no need to arrive at such high user numbers since we do have the technology to control the amount of energy needed to cool such a residence in a much more efficient manner.

The numbers are sobering! Using the RESFEN 3.1 ( Lawrence Berkley National Laboratory, Building Technologies Department) program for the simulation of different insulation values in a given setting and home size, this is an example we simulated:

Location Phoenix, AZ, home size 3,000sq feet, window area 440 sq.feet:

a) Total usage per year for heating/cooling with windows of an U-value 1,2 = 9278 KWh and 18 MBtu (gas)

    b) Total usage per year, using a high insulated window with an U-value of 0,17= 6141KWh and 9,8 MBtu

As one can see, there is nearly a 60% and 85% difference between the low and high-end window package!

My company SwissShade + Security, Inc. is importing windows and doors from Germany. There the government mandates what insulation values windows and doors have to have and therefore the manufacturers come up with products which in the light of energy conservation by far outdo most fenestration products available in the US.

In addition, people in Europe are very much aware of the impact an energy crisis can have on society in general and especially on the economy. The crisis in 1970 changed peoples attitude towards energy conservation radically. Suddenly it became clear that everybody's help was needed in order to guarantee a steady supply of affordable energy.

We in the USA are not used to conserve energy. Up to now, gasoline, electricity, coal was in abundance and the price was far below world standards. There was no need to change one's attitude.

Maybe the current energy crisis in California and the fact that the price for electricity went up 49% last week will help to open peoples minds and direct us to change our way of thinking.

As a businessman, it is in my utmost interest to help creating this new energy awareness. Our company can only sell windows and doors as long as the economy allows people to buy our products. An energy crisis hurts the economy and ultimately our company and our employees.

In addition, I strongly believe that the protection and preservation of our environment is also up to each one of us individually. What else can we give our children to look forward to if not an healthy environment?

This web page is designed to educate all of us: questions, solutions and facts regarding energy usage, energy abuse, potential energy savings and alternative ideas. If you have any constructive input, please e-mail us and we will be glad to add it to the page.

Franz Brun, President, SwissShade + Security, Inc.

The following article was written by Paul Fisette, the director of the Building Materials Technology and Management Program at the University of Massachusetts, Amherst, MA..

It is a very comprehensive study of how today's high-tech windows work and what to look for when making your next purchase. It covers topics such as: low-E coatings, U-values, Argon, Frame Materials, modern and high-tech Vinyl Windows, energy savings and more.

Understanding Energy-Efficient Windows

How today's high-tech windows work and what to look for when making your next purchase. A respected builderI know told me how he learned the true value of energy-efficient windows. In the course of his business, he installed a builder's line of windows from a well-known manufacturer in every house he built. He felt good about his choice; he purchased the windows from a manufacturer with a reputation for quality, but they cost 10% less than the same manufacturer's standard line of low-E, argon-filled windows, saving him about $600 per house. He even put them in his own new home. The first winter he lived there, though, he noticed that the windows seemed cold. Only then did he compare the U-values with the same manufacturer's standard windows. He did some math and concluded that his windows were costing him about $150 a year. By his estimation, the low-E windows would have paid for themselves in four years and made his home more comfortable for their entire life span.

Window choice has a real impact on heating and cooling costs. This chart is based on a computer model of heating costs for a 1,540-sq. ft. house with R-30 ceiling insulation and R-19 in the walls and floor. The window area is equal to 15% of the floor area.

 

My friend based his conclusions on widely accepted averages, and although certainly not exact, they were probably not far off the mark. Experiences such as his are common, yet they are easily avoidable with a basic understanding of how energy-efficient windows work. When you choose new windows, appearance is often the first consideration. Initial cost is the next issue: Which window within the favored style costs the least? But liking a window's appearance is a fuzzy proposition, and cost really depends on durability and on the energy dollars pumped through the windows each year (chart above). I am convinced that if we could see energy loss as we see color and shape, energy performance would top the list of window considerations.

Windows are thermal holes. An average home may lose 30% of its heat or air-conditioning energy through its windows. Energy-efficient windows save money each and every month. There are even some cases where new windows can be net energy gainers. The payback period for selecting energy-efficient units ranges from two years to ten years. In new construction, their higher initial cost can be offset because you'll probably need a smaller, less expensive heating and cooling system. And more-durable windows may cost less in the long haul because of lowered maintenance and replacement costs. Plus, you'll be more comfortable the whole while you live with them.

 

Windows lose and gain heat by conduction, convection, radiation and air leakage. This heat transfer is expressed with U-values, or U-factors. U-values are the mathematical inverse of R-values. So an R-value of 2 equals a U-value of 1/2, or 0.5. Unlike R-values, lower U-value indicates higher insulating value.

Windows lose heat in four ways. The rate at which a window loses

heat through the combination of the four is called its U-value. It is the

inverse of the R-value, so the lower the U-value, the greater the

insulative value of the window.

Conduction is the movement of heat through a solid material. Touch a hot skillet, and you feel heat conducted from the stove through the pan. Heat flows through a window much the same way. With a less conductive material, you impede heat flow. Multiple-glazed windows trap low-conductance gas such as argon between panes of glass. Thermally resistant edge spacers and window frames reduce conduction, too.

Convection is another way heat moves through windows. In a cold climate, heated indoor air rubs against the interior surface of window glass. The air cools, becomes more dense and drops toward the floor. As the stream of air drops, warm air rushes in to take its place at the glass surface. The cycle, a connective loop, is self-perpetuating. You recognize this movement as a cold draft and turn up the heat. Unfortunately, each 1°F increase in thermostat setting increases energy use 2%. Multiple panes of glass separated by low-conductance gas fillings and warm edge spacers, combined with thermally resistant frames, raise inboard glass temperatures, slow convection and improve comfort.

Radiant transfer is the movement of heat as long-wave heat energy from a warmer body to a cooler body. Radiant transfer is the warm feeling on your face when you stand near a woodstove. Conversely, your face feels cool when it radiates its heat to a cold sheet of window glass. But radiant-heat loss is more than a perception. Clear glass absorbs heat and radiates it outdoors. Radiant-heat loss through windows can be greatly reduced by placing low-E coatings on glass that reflect specific wavelengths of energy. In the same way, low-E coatings keep the summer heat out.

 

Low-E glass reflects heat energy while admitting visible light.

This keeps heat out during the summer and during the winter.

In the winter, low-angle visible light passes into the house and is absorbed by the home's interior.

Air leakage siphons about half of an average home's heating and cooling energy to the outdoors. Air leakage through windows is responsible for much of this loss. Well-designed windows have durable weather-stripping and high-quality closing devices that effectively block air leakage. Hinged windows such as casements and awnings clamp more tightly against weather-stripping than do double-hung windows. But the difference is slight; well-made double hungs are acceptable. How well the individual pieces of the window unit are joined together also affects air leakage. Glass-to-frame, frame-to-frame and sash-to-frame connections must be tight. The technical specifications for windows list values for air leakage as cubic feet per minute per square foot of window. Look for windows with certified air-leakage rates of less than 0.30 cfm/ft2. Lowest values are best

Letting in the right amount of sun

In a cold climate we welcome the sun's heat and light most of the time. And once we capture the heat, we don't want to give it up. In a warm climate, we don't want the heat, but we do want the light. Advances in window technology let us have it both ways.

Less than half of the sun's energy is visible. Longer wavelengths--beyond the red part of the visible spectrum--are infrared, which is felt as heat. Shorter wavelengths, beyond purple, are ultraviolet (UV). When the sun's energy strikes a window, visible light, heat and UV are either reflected, absorbed or transmitted into the building.

Only a fraction of the sun's energy is visible. There are windows that selectively block fabric-fading UV, visible light or infrared, which is felt as heat. Windows that block most UV and infrared while admitting visible light work well in cooling climates. For heating climates, choose windows that block UV while admitting heat and light.

Enter low-E glass coatings, transparent metallic oxides that reflect up to 90% of long-wave heat energy, while passing shorter wave, visible light. In hot climates, they reflect the sun's long-wave heat energy while admitting visible light, thereby keeping the house cooler in the summer. And in cold climates, they reflect long-wave radiant heat back into the house, again while admitting visible light. This shorter wavelength visible light is absorbed by floors, walls and furniture. It reradiates from them as long-wave heat energy that the reflective, low-E coating keeps inside. Low-E coatings work best in heating climates when applied to the internal, or interpane, surface of the interior pane. Conversely, in cooling climates, low-E coatings work best applied to the interpane surface of the exterior pane.

Low-E coatings improve the insulating value of a window roughly as much as adding an additional pane of glass does. And combining low-E coatings with low-conductance gas fillings, such as argon or krypton, boosts energy efficiency by nearly 100% over clear glass. Argon and krypton are safe, inert gases, and they will leak from the window over time. Studies suggest a 10% loss over the course of 20 years, but that will reduce the U-value of the unit by only a few percent. The added cost for low-E coatings and low-conductance gas fillings is only about 5% of the window's overall cost. It's a no-brainer.

Taking in the view

Windows with high visible transmittance (VT) are easy to see through and admit natural daylight. Besides giving you a nice view, high-VT windows can save energy because you need less artificial light. Some tints and coatings that block heat also reduce visible transmission, so be careful. Manufacturers list the VTs of windows as comparisons with the amount of visible light that would pass through an open hole in the wall the same size as the window. VT is sometimes expressed as a "whole-window" value including the effect of the frame. What is important is the ability to see through the glass, not the frame, so be sure you get the VT of the glass, not of the entire unit.

The VT in residential windows extends from a shady 15% for some tinted glass up to 90% for clear glass. To most people, glass with VT values above 60% looks clear. Any value below 50% begins to look dark and/or reflective. Dariush Arasteh, staff scientist at Lawrence Berkeley Laboratory, warns, "People have very different perceptions of what is clear and what has a tint of color, especially when they look through glass at an angle." Look at a sample of glass outdoors and judge for yourself before you decide to order the window.

It's warm in the sun

Manufacturers have long used shading coefficient (SC) to describe how much solar heat their windows transmit. A totally opaque unit scores 0, and a single pane of clear glass scores 1 on this comparative scale. A clear double-pane window scores 0.84 because it allows 84% as much heat to pass as a single pane of glass.

Solar-heat-gain coefficient (SHGC) is the new, more accurate tool that is replacing SC to describe solar-heat gain. SHGC is the fraction of available solar heat that successfully passes through a window. It, too, uses a scale of 0, for none, to 1 for 100% of available light. The key difference is that SHGC is based on a percentage of available solar heat rather than on a percentage of what comes through a single pane of glass. It considers various sun angles and the shading effect of the window frame.

Glass coatings are formulated to select specific wavelengths of energy. It is possible to have a glass coating that blocks long-wave heat energy (low SHGC) while allowing generous amounts of visible light (high VT) to enter a home. This formulation is ideal in warm climates. A low SHGC can reduce air-conditioning bills more than if you increased the insulative value of your window with an additional pane of glass. I recommend a SHGC under 0.40 for hot climates. In cold climates you want both high VT and high SHGC. I recommend an SHGC of 0.55 and above in the North. In swing climates such as Washington, D.C., choosing a SHGC between 0.40 and 0.55 is reasonable because there is a tradeoff between cooling and heating loads. For people in swing climates, Arasteh suggests, "Think about your specific comfort needs when specifying SHGC. If you like wearing sweaters and hate being overheated in the summer, then a low SHGC may be the choice for you." Choose the blend of glass coatings that works best in your climate and exposure.

Preventing UV-damage

Windows that block UV-radiation reduce fabric fading. Expect to find windows off the shelf that block more than 75% of the UV-energy. Contrary to conventional wisdom, some visible light fades fabric, too. Some manufacturers use the Krochmann Damage Function to rate a window's ability to limit fabric-fading potential. It expresses the percentage of both UV and of that portion of the visible spectrum that passes through the window and causes fading. Lower numbers are better.

Window manufacturers sometimes boast R-8 (U-0.125) values. Be careful. This may be only the value at the center of the glass, which is always artificially higher than the whole-unit value. Look for whole-unit values of U-0.33 or better. Some manufacturers stretch low-E coated plastic film within the gas-filled airspace of double-glazed units to provide an effective third or fourth "pane." The weight of these windows is comparable to double glazing, and the true overall window performance is boosted to levels of U-0.17 or better for some. These units are pricey, but they can be more energy efficient than walls in cold climates. The R-value is lower than a typical wall, but if triple-glazed units are designed with a high SHGC and are placed in a sunny wall, they can be net energy gainers.

Keeping warm around the edges

If you've lived in a cold climate, you've seen condensation and even frost on windows. When warm indoor air cools below its dewpoint, liquid water condenses on the glass. Condensation typically develops around the edges of window glass. No surprise. The edge is where most multiple-pane glazing is held apart by highly conductive aluminum spacers.

The coldest part of a multiple-glazed window is around its edges. It's worse with true divided-lite windows; because each lite has edge spacers, the ratio of cold edge to warm center is much higher than with regular insulated windows. Moist conditions support mold growth, and hasten decay and paint failure. Condensation is the No. 1 reason for window-related callbacks. Warm edges reduce the chance of condensation forming.

 

Energy-efficient glazing reduces winter condensation. When low glass temperatures cause inside air to reach its dew point, water condenses on the window. The chart indicates the points where indoor humidity and outdoor temperature combine to cause condensation on various types of glazing. This chart is based on center-of-the-glass temperatures, but the edges are always colder, and condensation usually begins there.

The material the spacer is made from affects the rate that heat travels through a window's edge. Many window makers now offer warm edge spacers as standard fare. Aluminum spacers are not acceptable. The best windows use less conductive materials such as thin stainless steel, plastic, foam and rubber. Warm edge spacers can improve the U-value of a window by 10% and boost the edge temperature by around 5°F, thereby reducing condensation.

Good frames insulate.

The most widely available window frames are wood (including vinyl-clad and aluminum-clad wood frames), with 46% of the market. Hollow vinyl frames hold 36% of the market, and aluminum runs a distant third, with a 17% market share. A trickle of alternative materials such as wood-resin composites, fiberglass, PVC foam and insulated vinyl makes up another 1% of windows sold. A window's frame represents about 25% of its area. So it's important that the frame material be thermally nonconductive. For the most part, wood and vinyl are the best performers, and they work equally well. Aluminum frames are typically poor energy performers.

Connections where the frame joins together must be tightly sealed to keep out water and air. Weather-stripping needs to seal tightly after hundreds of window closings, rain wettings, sun dryings and winter freezings. Inexpensive, flimsy plastic, metal or brushlike materials don't last. Compressible gaskets like those used to seal car doors are best. Closures must clinch windows tightly shut. Look carefully at these components, and ask your architect or builder about a particular brand's track record. Pick longtime winners. Let others experiment with a new brand.

Wood is typically the most-expensive frame material. Maintenance is one of the biggest drawbacks to using solid-wood windows. Wood rots, shrinks and swells. Paint fails. Solid wood requires frequent, fussy maintenance. On the other hand, well-maintained wood looks good, is stable and can be recolored easily. Clad versions are the easiest to maintain. On the down side, if you get sick of the cladding color, too bad. When you choose either a solid or clad version, be sure that the manufacturer has treated its wood frames with water-repellent preservative to improve durability, paint retention and dimensional stability.

Vinyl windows are built to move

Vinyl windows have been around for 35 years. Vinyl is energy efficient, durable, rotproof, insectproof and weather resistant. It's made with chemicals that inhibit UV-degradation. Vinyl is colored throughout and requires no painting. The knock on vinyl is that it fades, can't be painted, becomes brittle with age and is thermally unstable (especially dark colors). Temperature changes cause it to contract and expand more than wood, aluminum and even the glass it holds. Vinyl frames have the potential for causing increased air leakage over time because of this movement. But Richard Walker, technical director of the American Architectural Manufacturers Association (AAMA, 1827 Walden Office Square, Suite 104, Schaumberg, IL 60173; 847-303-5664 ), is quick to say, "Vinyl windows are built with this movement in mind, and failures have not been recorded to cause concern." If you choose vinyl frames, specify light colors and heat-welded corners. Heat-welded corners hold up best over time.

The pigments that are used in paint are almost identical to those used in vinyl, but vinyl's color goes all the way through. Walker says, "A little rubdown with Soft Scrub or one of the products on our (AAMA) list of recommended cleaners will bring vinyl back to its original brilliance." I tried the Soft Scrub test and was impressed with how much brighter aged vinyl became. Not the original color, to be sure, but the scrubbing resulted in a marked improvement.

Fiberglass-frame windows are showing up in a few product lines. Fiberglass is extremely strong, and because it is made of glass fibers, the frames and the glass expand at the same rate. Fiberglass must be painted and is more expensive than vinyl. Owens Corning, Andersen and Marvin are three major manufacturers that produce fiberglass windows. Owens Corning is the only manufacturer that makes fiberglass windows with insulated frames. But before you get too excited, the whole-window U-value for a low-E argon-filled casement window carries the same 0.32 rating for both an uninsulated vinyl and an insulated fiberglass unit.

Aluminum-frame windows are durable, requiring little maintenance. However, they are energy siphons and shouldn't be used where energy efficiency is a consideration.

The range of window options available today is staggering. But a working knowledge of the terms and these few guidelines should make choosing windows a little less intimidating.

 

You might also want to get ahold of this book: Residential Windows: A Guide to New Technologies and Energy Performance by John Carmody and others, W. W. Norton & Co. Inc. (1996).

Verifying energy performance

Until recently, purchasing a window was a little bit like buying a mattress. With mattresses you get cushion firm, chiro protector and Posturepedic Plus. Huh? With windows you're promised energy performance with U- and R-values. But what does the advertised R-value mean? And does it mean the same for all windows? Hardly. Some manufacturers determine R-value by measuring conductance at a single point in the center of the glass and do not count heat transferred through the frame or through metal spacers at the edges of the window. They do not account for the air that leaks around the sash. Nor do they measure radiant-heat loss from the entire window unit. Others honestly report whole-window values.

All NFRC-rated windows have this label. Manufacturers must list U-value, but other values are optional. Tests used to determine the values are consistent, so this label is useful for comparing different manufacturers' windows. Compare this window's rating with the chart above.

Photo courtesy of NFRC.

In 1989, the National Fenestration Rating Council (NFRC) was formed to level the playing field in the window industry. NFRC's mission is to develop a national energy-performance rating system for windows and doors (FHB #111, p. 38). All NFRC-rated windows are tested using a reliable, standard procedure that measures energy transfer through the entire window unit. U-values, solar-heat-gain coefficients, visible-light transmittance values and air-leakage rates are now (or will be soon) listed on certified windows. When consumers see an NFRC label (photo above) on the windows they are considering, they can be sure that they have a reliable tool they can use to compare windows.

As of June 1997, NFRC had over 150 participants with more than 30,000 windows, doors and skylights in the program. "This includes all of the major manufacturers like Jeld-Wen, Andersen, Marvin, Pella, Certainteed, Owens Corning, Peachtree, etc.," says Susan Douglas, the NFRC's administrative director.

How the NFRC system works

Window manufacturers that want to be certified hire a NFRC-accredited lab. The lab simulates the thermal performance of the windows with computers. Entire unit performance--including frame, spacer and glass--is measured. Windows with the highest and lowest simulated U-values in each product line (such as casements) are physically tested to verify the computer simulation. An independent NFRC-licensed inspection agency reviews the computer simulations and randomly pulls window units from the factory floor as test samples. Physical test values must fall within 10% of the computer predictions for a product line to be validated.

Presently, manufacturers that participate in the NFRC program must include certified U-values on the label. They also elect whether to include solar-heat-gain coefficient, visible-light transmittance and emissivity on the label. NFRC has created a technical procedure to measure air leakage and expected to have the details ironed out by January 1998. Douglas promises, "You can expect air-leakage values soon." Solar-heat gain is based solely on computer simulation, while visible transmittance, air leakage and emittance are physically measured values. The NFRC does not evaluate durability now, but the group does have a long-term performance subcommittee in place and expects to consider durability in the future.

Certified products have temporary and permanent markings. The big, temporary label is placed in a highly visible spot on the window. A small permanent NFRC serial code is etched on an inconspicuous part of the window, such as a spacer or metal strip. Permanent labels are useful. Potential buyers of older homes often ask, "What kind of windows are these?" A phone call to the NFRC will provide the brand and rating for the unit. Labels provide builders, designers, code officials and consumers with information needed to verify code compliance and a reliable level of performance.

Beyond labels

RESFEN, a computer program developed by Lawrence Berkeley Laboratory, enables you to minimize energy use, maximize comfort, control glare and maximize natural lighting in your home design. Builders, architects or consumers who want to fine-tune a design and choose specific windows for specific exposures on a house in a particular climate can order RESFEN from the NFRC for about $15. The NFRC Certified Product Directory and RESFEN are available from NFRC, 1300 Spring St., Suite 500, Silver Spring, MD 20910; (301) 589-6372, www.nfrc.org.

Governmental Energy Resources:

 

-Paul Fisette is director of the Building Materials Technology and Management Program at the University of Massachusetts in Amherst, MA. http://www.umass.edu/bmatwt. Chart information courtesy of W. W. Norton & Co. Inc., except where noted. Photo: Brian Vanden Brink. Drawings: Dan Thornton. From FH #114, pp. 68-73.

top