I've been reading all these posts on the mutitude of so-called "Green" websites and blogs with great interest. They mostly say you should get rid of your old and historic windows in favor of disposable replacement windows. This is truly anti-green and anti-energy efficiency!
Bottom line, I'm a historic property developer in the upper Midwest. In over 160 projects, small residential to huge commercial, I've never replaced a window that wasn't missing in the first place.
Most of these posts whine about preservation ordinances and federal preservation rules. I love working with historic preservation commissions, state historic preservation offices and the National Park Service. Their regulations are all based on The Secretary of the Interiors Standards for Rehabilitation. These guidelines recommend keeping as much original material as possible. There's nothing oppressive about this for my projects. I actually save money and get better performance as a result. I don't install disposable replacement windows for a variety of reasons:
1) They only last on average about 15 years.
2) From a green/environmental standpoint, throwing away a perfectly good window is environmentally irresponsible.
3) After restoration & weatherization, the historic windows outperform most disposable replacements. This includes the entire window opening with sash weights.
4) On average, windows only make up 10% of the energy footprint.
5) Glass is a terrible insulator. R-1, R-2 or R-4 is all just hype by the disposable window manufacturers. Windows are there to let in light and to create ventilation, not insulation
6) All the windows I restore and weather strip for my development projects can be easily cleaned on the exterior from the inerior of the structure.
7) A properly weatherstripped old or historic window and general window envelope has less air infiltration than a disposable replacement..
8) The average payback for a residential disposable replacement is about 40 years and 150 years plus for commercial. Paybacks for restored and weather stripped historic windows, that perform similarly, run about 3 to 7 years with a proper storm.
9) Restoring and weatherizing old and historic wood windows costs less than replacing with a so-called comparable, disposable replacement.
None of these facts are conjecture, they're are proven in study after study. I'm a founding member of the not-for-profit, National Window Preservation Standards Collaborative. We have been conducting extensive testing and have written the Window Preservation Standards book that sites all the objective research that backs up this information as well a detailed standards for the best practices in repair, restoration and weatherization of old and historic windows. This book is now available for you to order online at www.windowstandards.org .
As a property developer my buildings must be energy efficient and I need to make a fair profit. I can't get either if I replace original windows.
There is nothing green or sustainable about a disposable replacement window.