Actually, during the winter, self-cleaning glass is more efficient because clean glass allows more solar heat through it.
Several major international glass manufacturers produce the self-cleaning glass. Check with them or your window manufacturer to see if it is offered. The special self-cleaning coating is invisible and is actually part of the glass pane, so it is as durable as the window glass surface itself.
The coating self cleans the window by two continuous processes. Safe chemicals in the glass surface create a photocatalytic process when sunlight (specifically ultraviolet - UV) strikes the glass. This process breaks down and disintegrates organic dirt, which is the majority of dirt on windows.
The special surface also has a hydrophilic property which causes water to sheet and flow down the glass instead of forming beads when it rains. Every time it rains, the glass is cleaned or spray it off with a hose. You can see outdoors during a heavy rain almost as well as when it is dry.
There are many new types of decorative glass available, but you probably won't be able to find it with the self-cleaning surface. Just adding a few decorative windows (some very ornate ones are quite expensive) to your home can dramatically improve its appearance from indoors and out.
Some decorative windows are very efficient even though they may have metal and other trim in the glass. The most efficient ones sandwich the decorative pane of glass between two plain panes. This protects the decorative pane while it creates two insulating air gaps inside the glass.
Most major window manufacturers will offer several or all of these decorative glass options: stained, leaded, glue chip, beveled, carved, hammered, multifaceted, granite, jeweled, art-deco, etched, and orchid. Privacy and security, such as impact-resistance, glass is another option.
If your budget is tight, consider decorative glass panels that snap over an existing window. These kits include finishing wood trim strips so the add-on glass panel appears to be an integral part of your existing window pane.
Often, a small fixed (non-opening) window with a unique shape and tinted glass is attractive and reasonably priced. Arched styles, such as Gothic or unequal legs, are popular.
Write for (instantly download - www.dulley.com) Update Bulletin No. 413 - buyer's guide of 14 manufacturers of self-cleaning glass and complete windows with decorative glass listing styles, frame materials/colors, decorative glass options, and features. Please include $3 and a business-size SASE.
James Dulley, c/o Casa Grande Dispatch, 6906 Royalgreen Dr., Cincinnati, OH 45244
Dear Jim: I am considering several designs for a new home. The home will be built on a sloping lot. What is the insulation value of the soil and is it necessary to add wall insulation where it is covered with ground? - Ken F.
Dear Ken: Soil does not have a particularly high insulation R-value, especially when it is wet. Its advantage for underground homes is that its temperature stays fairly constant several feet below the surface.
If you are building a home into a hill, it would be wise to use exterior foam wall insulation against the dirt and where the foundation is exposed. Extruded polystyrene foam insulation board would be a good choice.