Energy conservation and restoration of stained glass windows

by Donald Samick

Stained glass and decorative arts studios have been dedicated to serving the artistic needs of churches and synagogues for many years. However, since 1973 it has become increasingly evident that a more pressing need is arising. Energy needs have taken precedence over artistic needs and studios are expanding their expertise into the energy field.

Even though energy losses are not limited to stained glass but occur through all single glazed areas, the insulation of a stained glass window poses more of a problem than does the typical window. By covering a stained glass window a church can save about 50% of the energy - either heating in winter or cooling in the summer - that is lost through the single· thick glass, a high conductor of heat and cold. There is also a greater loss when the windows are old, and the putty between the glass and lead strips hardens and cracks from expansion and contraction over time. A still greater heat loss takes place around an old steel ventilator which either does not shut tight due to sagging or corrosion, or which if it does close properly, is not weather-stripped. In the latter case, steel abuts on steel, which allows a great deal of energy to be transferred through these high conductors to the outside.

As for the problem of heat loss through steel ventilators, it is best to replace the steel ventilator with a modern aluminum unit that is double glazed, weather-stripped, and maintenance free. It should also be mentioned that it does no good to "sandwich" a piece of thin plastic covering against the stained glass in a ventilator. When it is an old steel ventilator that probably does not close tightly, the major portion of energy loss continues to occur. Furthermore, any thrown object will bend the plastic inward far enough to break the stained glass without being able to break the "space age" unbreakable plastic covering.

This standard energy loss, to which all unprotected stained glass windows are subject, is often further accentuated by failure to undertake certain relatively minor repairs. There is always the broken window which never gets repaired, either because the glass is irreplaceable artistically or because no one is available or capable of performing the needed repairs. Often some simple caulking is all that is needed, but due to the inaccessibility of some windows or just lack of awareness of this need, the caulking remains undone allowing a large amount of energy loss to occur.

A stained glass window can be covered with two basic types of material: glass or plastic. Different thicknesses of these protective covering materials are required depending upon the size of the window. Probably the most widely used plastics are polycarbonates, sold under the trade names of Lexan manufactured by General Electric and Tuffack manufactured by Rohm. General Electric guarantees its product unbreakable for three years. Rohm states that its product is "virtually unbreakable." These products will yellow over time, so this is a major consideration. Also available are Plexiglas, acrylite, and lucite, which are plastics that can crack upon impact but are seventeen times stronger than 1/4" plate glass. They will remain clear for a much longer period of time.

Plastics are easier to work with and install than glass. However, they often tend to have a slightly wavy appearance and sometimes a purplish cast when installed. Over time, they will scratch and accumulate dirt if not properly cleaned and maintained. This leads to an undesirable appearance from the exterior and gradually reduces the amount of light. This problem is especially severe in high pollution areas.

Glass, which was used exclusively until about thirty-five years ago when plastics became popular, is cleaned for the most part by rain and wind. It will withstand air pollution much longer, will not scratch, and can be cleaned very easily. Its great disadvantage, of course, is its relatively easy breakability.

An additional solution to this problem is the use of laminated architectural glass. With a polyvinyl butyral center layer bonded between two sheets of glass, laminated glass combines the clarity and clean appearance of glass with the damage protection afforded by plastics. Laminated glass may shatter upon impact, but it will break safely without glass splinters and will not allow flying objects to penetrate through the stained glass behind.

If recaulking is needed, this should be applied around the perimeter of a window and at the horizontal joints. Old putty or dried caulking should be removed. It is worthwhile to apply a good grade of silicone caulking that will expand and contract with the changes of temperature and the movement of the building. A local commercial glass contractor can perform this work where it requires scaffolding. Once a good sealant is applied, one usually does not have to be concerned again about this problem. Use of inexpensive caulking is never advisable.

Whatever material is used as a protective covering for stained glass windows, it will provide the following advantages: reduction in energy loss, reduction in outside noise, deterrence of vandalism and damage due to accidents, and protection of the vulnerable lead strips and glass from corrosion due to pollutants in the air.

This major work of American stained glass, designed by noted artist Ella Condie Lamb, was first unveiled al Wells College on June 11, 1902 and dedicated to the memory of Wells' first Alumna Trustee, Stella Goodrich Russell. On September 4, 1989, the stained glass treasure was again unveiled and rededicated in remembrance of Margaret E. Martindale Meserole, President of the Class of 1976. The restoration was completed by the J & R Lamb Studios, the original makers, established in New York City in 1857, now of Clifton, N.J. The new cabinet, especially designed by Lamb Studios, was crafted by the Bartolotta Brothers, Inc. of Auburn, N.Y.



The cost of installing a protective covering for stained glass windows can vary widely.

Click here for more information.

Also, if a church decides to go ahead with a protective covering project, it should obtain several bids for the work from experienced firms who understand stained glass windows and who can make needed repairs and analyze the condition of the windows as they are working around them. Be aware that different companies frequently use different specifications in their bids, make sure "apples are being compared with apples." Turn down those thermostats when the building is not being used - and even when it is. Use a locked thermostat. Unplug that refrigerator during the summer when it is not used. Schedule church meetings on Mondays while the building is still warm from Sunday. Insulate the building. Weather-strip doors and windows. Tune up the furnace so it is working at maximum efficiency. Lastly, and most important of all, realize that for energy conservation efforts to make real headway, people must change their accustomed ways.

How can you tell if your stained glass windows need restoration?

Click here for more information.
Click here to see our restoration stained glass window gallery