A replacement window is custom built to fit within a pre-existing window opening. A new construction window has nailing fins or flanges on the exterior and is designed for homes yet to be built, or where an existing window has to be removed down to the studs. Replacement windows fit your old opening without removing interior or exterior casings, leaving your siding, walls and trim intact — which minimizes both disruption and cost.

"Off the shelf" standard or lumberyard windows are less expensive at the start, until you consider the increased labor and the problem of trimming out the inside of the opening. Custom windows give the best fit and energy performance for your home. All replacement windows will save on heating and cooling bills and noticeably reduce the noise entering your home.

Vinyl windows come factory-finished in their color and are nearly maintenance free. Replacement windows have no storm windows — the screens lift out easily, so the glass can be cleaned from inside the home. Clean frames and glass with mild soap and water and a soft cloth, keep sill tracks and weep holes free of dirt and debris so water can drain properly, and wash the weatherstripping with mild soap and water to remove grit and keep the seal tight. Always use the mildest cleaner possible; abrasive cleansers can harm vinyl and PVC surfaces and other window components.

Insulated glass packages featuring Low-E glass reduce the ultraviolet rays that enter the home and fade furniture, drapes, carpet and woodwork. Low-E is a very thin coating that helps reflect heat away from the glass surface, and is the most effective way to increase a window's energy efficiency. Argon is a colorless, odorless, nonflammable, nontoxic inert gas that is heavier than air; it further improves efficiency and makes the home quieter.

Condensation forms when warm humid air meets a cool glass surface, which happens when interior and exterior conditions differ sharply. When humidity is regulated, condensation is very unlikely. Energy efficient windows keep the outside glass closer to the exterior air temperature; double pane glass, Low-E coatings and argon fill all reduce unwanted heat flow and the condensation that comes with it.

Consider replacement if your wood frames are rotting, if you get excessive condensation, or if you feel drafts standing next to them. The same goes for single-pane windows, windows that aren't energy efficient, windows that need constant upkeep, or fading furniture and carpets. Windows can be installed in winter or summer with great results.

ENERGY STAR is a voluntary program of the U.S. Environmental Protection Agency that helps businesses and individuals save money and protect the climate through superior energy efficiency. The EPA and the U.S. Department of Energy use the ENERGY STAR® label to help consumers recognizes energy-efficient products.