 | Bob Crager of Lewis Street Glass is a 26 year veteran in the glass business. Lewis Street Glass is a leading Wichita Glass company, serving the entire Wichita/Sedgwick County area since 1919. They do anything and everything having to do with glass, both residential and commercial. They also do Auto glass. They are located at 743 South Market, facing Kellogg on the South, and you can reach them by phone at (316) 263-8259. You can email Bob Crager at bcrager@lewisstreetglass.com |
Glass
2009-08-01 12:16:00
Getting hot inside, with AC going
Answer: This time of year is really brutal with the 100 plus degree heat, but what you don’t recognize as much is that those same windows, if not properly maintained, are hurting you the same way in the coldest part of the winter too! You see, the windows in your home, or even in your commercial building, are like “thermal holes”. On average, you can lose over 30 percent of your heating and/or air conditioning through those openings called windows! That’s a lot! There are some great alternatives to your situation, such as completely replacing with some new energy efficient windows. That’s a move that will begin immediately to save you money nearly every single day. New windows can be “net energy gainers”, and the average payback period for replacing with these new windows is between 24 months to as much as 120 months. If you were building a new home, the higher initial investment can usually be offset due to the fact that you’ll probably need a smaller, less expensive heating and cooling system. In any case, more durable windows could cost you less in the long run because of lower maintenance and replacement costs. To say nothing of the elevated creature comforts you’ll enjoy while you live there. When you’re considering new glass windows, appearance and initial cost are the two considerations you’ll want the information on first. In other words, which window that you like the style of costs the least? It’s pretty certain that if you could visualize your energy losses for the year the same way you can see colors and shapes, your first consideration would be the window’s energy performance. That would top your list of considerations.
You see, your windows gain and lose heat by four ways. Those are conduction, convection, radiation and leaking! Let’s talk for a minute about those.
Conduction is where heat moves through a solid material. Touch a hot skillet, and what you feel is heat conducted from the stove through the metal skillet. Heat flows through window glass in much the same way. You can impede the heat flow with less conductive material. For instance, multiple glazed windows trap low conductance gas, such as argon, between the panes of glass. The edge spacers and window frames are thermally resistant components, and reduce conduction as well.
Convection is another way that heat moves through glass windows. When your furnace is running in the cold part of the year, your heated indoor air comes up against the interior surface of your window glass. The air cools, becomes more dense, and falls toward the floor. As this air drops, warmer air rushes in to take its place on the surface of the glass. This cycle, known as a “convective loop”, is self perpetuating. You feel this movement of air as a “cold draft”, and turn up the thermostat. The bad news is that each degree of increase in your thermostat setting increases your energy use by 2 percent! Multiple panes of glass, known as “thermopanes”, separated by the low conductance gas fillings and warm edge spacers, when combined with thermally resistant window frames, raise your inboard glass temperatures, slow down the convection, and improve your creature comforts!
Radiant heat transfer is the movement of “long-wave heat energy” from a warmer body to a cooler body. This transfer is the “warm feeling on your face” when you stand next to a wood stove. Conversely, your face feels cool when it radiates its heat to a cold sheet of window glass. Radiant heat loss is more than just a “perception”. Clear glass absorbs heat and re-radiates it to the outdoors. There are some things that can be done to greatly reduce these losses.
We’ll talk next month about the 4th method of heat transfer, which is air leakage, and some methods of helping your situation in all of these circumstances. This time of year, you just cannot afford to not pay attention to how much of your money is flowing right out of your glass surfaces and disappearing into thin air! Thanks for your attention…more next month.
