What's a Double Hung Window?

Last week I had a conversation with an old house owner out west. She really wanted to replace her windows so I told her that she should go ahead and replace her 100-year-old windows if she liked spending more money than necessary for something that won't be as energy efficient as what she has. I suggested she may want new windows but I have rarely seen a house built before 1950 that needed them.

Double hung windows (one window sash on top and one on the bottom) are the most popular in America and seem to have been invented sometime  in the 1400's. There original purpose was primarily as an early air conditioning system. Vintage double hung's have two window sashes that move up and down utilizing a counter balance system with a cast iron weight, a pulley and rope to connect the weight to the side of the window sash. If you drop the top window sash down three inches and raise the lower sash three inches a very interesting thing happens. The heat and humidity leaves the house through the top gap and cooler breezes enter the house through the lower gap.

Now, I love air conditioning but when we use our windows in this fashion, I don't have to turn on the air conditioning until mid-July and it goes off in mid-August. We estimate we're saving between 20% and 30% on our summer electricity bills without sacrificing comfort to do so.

In most pre-1960 homes, with wood windows, there is also a storm window that protects them. Part of the reason we don't use our windows as air conditioning systems is that we replaced the original wooden storm windows with aluminum, self-storing storms. Folks just got tired of climbing up and down ladders in the spring and fall to switch out glass storms with screen storms. Whoever invented these aluminum storms did so because of this fact.

The problem with this design is that there is only a screen on the bottom and so everyone painted their top window sashes shut. Not only did this stop people from using their double-hung windows as air conditioning, the windows got much less use and people didn't pay much attention to maintenance issues.

One of the primary problems I have with new double paned (insulated glass) windows, wood or vinyl, is they have no storms. Your interior double hung units, old or new, were never intended to take a direct hit from the weather. From the 1400's until around the 1870's most windows had wooden storm shutters. Then wooden storms were invented in favor of shutters. These were more practical than hassling with closing the shutters every time a storm was coming.

The good news is that there are now combination wooden storms that are either self-storing or have glass that can be taken out of the wood frame from inside the house. No more trudging up and down the ladder to change storms and screens twice a year. These storms also have full screens so your windows can be used as they were intended.

It will take a consumer 20 to 50 years to get any payback (saving enough energy to pay for the new windows) from replacement windows with double paned glass. Considering the following statements in the window industries trade magazine, Glass Magazine, they make the case for restoration.

July 2001 Glass Magazine, By Editor, Charles Cumpstom, "The consumer's perception of glass is significantly different from the industry's. While some in the industry think a 15-year life is adequate, it is the rare homeowner who envisions replacing all his windows in 15 years."  

Another article in 1995 in Glass Magazine by Ted Hart states, "Remember our industry, with rare exception, has chosen to hide the fact that insulating glass does have a life expectancy. It is a crime that with full knowledge and total capability to build a superior unit, most of the industry chooses to manufacture an inferior single-seal unit." 

Single seal units are still the norm in plastic/vinyl and most stock wood windows with an average seal life of 2 to 6 years according to accelerated testing by the flat glass manufacturer, IG Cardinal. 

For most homes, you will never find a simpler, more cost effective and energy efficient window unit than an original weatherized, single paned, double hung window with a combination wood storm.

Wooden, Combination & Traditional Storm Window Manufacturers:

• Adams Architectural, Dubuque, IA, 1-888-285-8120, www.adamsarch.com
• Acker Millwork Co, Milwaukee, WI 1-414-672-2200
• Marvin Windows (self-storing, wooden storms) www.marvin.com
• The Belvedere School for Hands on Preservation-Learn to make your own wood storms (see Belvedere School tab above)