XCEL Energy Makeover Contests and Colorado Energy Science Center

The Blind Spot has participated for three years with XCEL Energy and the CESC in the annual Energy Makeover Contests - two lucky winners each year get a serious home makeover and receive energy-efficient home improvements worth more than $25,000 each - all made possible by local companies that co-sponsored the contest.

We have learned extensively about energy-efficiency through this affiliation, and can help you to make the best overall decisions concerning window coverings and your home.

You can find out more about the contest and the sponsors by visiting the Smart Energy Living website here.

Window Energy Theory

• Windows provide FREE light
• A house with good window design is much more efficient than one with no windows at all
• WINDOW COVERINGS greatly enhance the energy benefit of windows
• HEAT is transferred three ways: CONDUCTION, CONVECTION AND RADIATION
• These processes follow a basic law of nature: heat energy tends to move from warmer areas to colder areas . There is no way to get around this fundamental principle; all we can do is slow the processes down.

Conduction	Convection	Radiation

Conduction - Conduction is the movement of heat through a solid material. Touch a hot skillet and you'll feel heat conducted from the electric coil trough the pan. Heat flows through the glass, spacers (metal strips that separate the panes of glass), and frame of a window in much the same way. Heat will flow from inside your home through the window to the outside. Interrupt the pathway with a less conductive material and you impede the flow of heat. Less conductive materials like insulation do this by trapping dead air between the solid fibers of insulation. Multiple-glazed windows do this by trapping low-conductance gas like argon and krypton in the space between the panes of glass. Thermally resistant spacers and window frames reduce conduction too.

Now add window coverings and you have yet one more barrier to the flow of heat through your windows, as long as the window coverings are installed correctly.

Convection - Convection is another way that heat moves through windows. In a cold climate, heated indoor air rubs against the interior surface of the window glass. The air is cooled, becomes more dense, and drops to the floor. As this stream of air drops to the floor, more warm air rushes to take its place at the glass surface. The cycle, called a convective loop, is self-perpetuating. The cold glass surface methodically strips heat from the indoor air. Sitting on a sofa, you recognize this convective movement as a cold draft and raise the thermostat. Unfortunately, each 1-degree increase in a thermostat setting, increases energy use by 2%! Instead, raise the temperature of the glass. Choose multiple glazings with low-conductance gas fillings, warm-edge spacers and thermally-resistant frames. They raise inboard glass temperatures, slow convection and improve comfort.

Or add properly installed window coverings to impede this process. Properly installed means that you have the "tightest fit possible" inside your window jamb so air cannot easily flow around the sides of your window coverings or down through the top. Additionally, have the bottom rail sit flush on the sill. If it does not reach the sill, the convection above takes place. You can actually feel the draft off your windows if you lift the rail from the sill. Place the rail on the sill and you can noticeably feel less draft (on cold windows).

If your windows coverings are installed outside your jamb, on the trim or on the wall, you can also reduce this convection process by covering the top with a board mounted valance, or cornice that impedes the loss of heat through the top.

Radiation - Radiant transfer is the movement of heat from a warmer body to a cooler body through energy waves. A good absorber is a good emitter. Most wood stoves are black for a good reason. Black absorbs and emits radiation best. You can feel a stove's radiant heat on your face across a room. In turn, your face feels cool when it radiates (emits) its heat to a cold sheet of window glass. This uncomfortable sensation, like convection, persuades you to boost the thermostat. Radiant heat loss is more than a perception: Clear glass absorbs heat and dumps it outdoors. Absorption and emission potentials of glass can be greatly reduced by placing coatings on glass that reflect specific wavelengths of energy. Low-"E" coatings emit less long-wave heat energy. In cold climates, more heat stays in the house. In hot climates, the heat stays outdoors. Low-E coatings improve the insulating value of window roughly the same as adding an additional pane of glass to a unit. So a double-glazed low-E window works as good as a triple-glazed clear window.

Now add window coverings to the equation and you have another absorber/reflector of the radiation gain. In our Colorado sun, we want to reflect back the sun to the outside in the Summer and use the solar gain from the sun in the Winter.

Seeing is Believing

This house was photographed during the winter using thermal photography, a process which exposes higher temperature zones as indicated by the color transitions. You will notice that the areas around the windows are particularly 'hot', proving that a significant amount of interior heat is escaping from these portions of the home.

The Most Energy Efficient Window Coverings

• Window Quilts
• Draperies
• Roman Shades
• Honeycomb Shades
• Others

Window Quilts

Air & moisture-tight fabric along with the 4-sided seal dramatically increases the insulating value! 5 Layers in design: Lining, high density fiber batting, internal reflective polyethylene moisture vapor barrier, high density fiber batting, fabric cover. R-value: 4.99 Shading coeff: .23 - .14

Draperies & Roman Shades - R-value: 3.0 - 5.0
	Depending on fabric and lining Can be thermally lined Type of pleating effects R-value

Honeycomb Shades - R-value: 2.0 - 4.8, Shading Coefficient: .44 -.21
Duette Architella from Hunter Douglas	Opaque R value: 7.22-7.73 *On low-E glass ** Data for Hunter Douglas brand Semi-Opaque R value: 5.48-6.02 * On low-E glass as compared with others on double pane glass
	Opaque Single cell: 4.3/.21 Double cell: 4.35/.35 Triple cell: 4.80/.24 * Data for Hunter Douglas brand Semi-Opaque Single cell: 2.0-3.9/.40-.31 Double cell: 4.35/.35 Triple cell: 4.80/.24
Duette® Honeycomb Shades has earned the highest energy-efficiency rating in the industry and ranks as the nation's best-selling honeycomb shade due to their single, double or triple thickness air-trapping construction. For French and sliding doors, Duette with VertiglideT provides the same honeycomb construction with the shade's pleats oriented vertically. Don't forget to cover the Skylights! There are several options for Duette Shades for covering skylights, which are a big source of heat loss in the winter and heat gain in the summer. This includes the new Duette PowerRise For Skylights options, which is far more affordable than previous motorized skylight shades and are installed with no wiring at all.

The Best Energy Efficient Products For  Year round Heating and Cooling Benefits

1. TrioT Convertible Shades.  While Trio convertible shades sometimes look like Duette honeycomb shades, the vanes expand and contract to allow the shade to operate.  With the R-Value of the semi-opaque version of Trio at 3.94, you can be assured that the newest product in the industry provides great efficiency.

2. Vertical Blinds can increase window insulation by 37 to 123 percent and block 95 to 99 percent of ultraviolet (UV) light. Hunter Douglas offers fabric, vinyl and aluminum styles in various finishes, as well as products that combine the softness of suede with the strength of metal. Hundreds of colors, textures and embossed patterns are available. R-values reach as high as 3.92 for vertical blinds.

3. Heritance Hardwood Shutters and Vinylbilt Shutters --It's reasonable to expect shutters to help reduce heating and cooling bills and protect furnishings. Shutters provide an R-Values of 2.75 and up.  They block 95% to 100% of unwanted UV rays.

4. Vignette® Window Shadings - have the gentle look of a fine drapery, but are made of generously contoured folds of rich fabrics. They provide a 49 percent increase in window insulation value and block 99 percent of UV light. Vignette, which has an R-value of 2.63. All colors and pleat sizes of Vignette shadings are now available in the EveScapeT fabric option, which is completely room darkening.