The earliest windows were literally holes in walls—maybe covered by animal skins, if the owner was ambitious, or the weather was  chilly—and were useful only for allowing a little air and light into the living space.  

 Eventually, mankind found ways to make windows both more useful and more  beautiful. The ancient Egyptians had shutters and cotton drapes, and the Romans  actually used glass in their windows. Mullioned panes and stained glass designs  came along centuries later to enhance windows and to show status and wealth.  During the 18th and 19th century in Europe, a property tax based on the number  of windows per dwelling, was a hotly protested issue. Property owners from that  period sometimes closed in the window spaces in protest of the government “stealing daylight" by taxing it.  

 For most of the last hundred years, the biggest issues with windows has been  planning for cross-ventilation in the days before air conditioning was common,  and making sure the windows were closed before it rained in. Over the last few  decades however, the door and window industry in America has evolved as a  separate niche in the construction industry. Windows are generally considered a  necessity and an amenity. They convey style, provide protection from the  elements, enhance ambiance and conserve energy—and like any other building element, they require routine maintenance and  replacement. The right combination of elements can mean the difference between  filling a hole in the side of the building or installing an energy efficient  architectural element that continues to add value and beauty to the property  for years to come.  

 A Big Project

 Replacing or repairing windows in a multi-storied, multi-unit condominium or  co-op is a major undertaking for everyone involved. The board, the residents,  the property management firm and the company selected to perform the work will  need a coherent plan and excellent communication skills to keep the project on  track and to minimize the disruptions for staff and residents.  

 According to the experts, windows generally have a 20- to 30-year life span  depending on the window material and finish, and the elements they're exposed  to. However, if windows were poorly or incorrectly installed, or if proper  maintenance such as caulking and painting has been inadequate, replacement will  be needed sooner rather than later. If maintenance has been thorough and  diligent, the life of the windows may well be extended.