New windows can change your home like no other home improvement can. Not only do they add light and improve air circulation, but new windows can also save you money by reducing the energy resources you use.
If you're not sure if your windows need to be replaced, look for the following signs of deterioration:
Many standard and specialty windows are now available with energy-saving features. Energy can be saved by using a low-emissivity glass coating that reduces the transfer of heat. The coating will also protect your indoor furniture and fabrics from sun damage. When you replace single-pane windows with double- or triple-pane windows, heat and cold can be trapped and tempered between panes instead of transferring straight into your room.
You may choose to change your windows for energy efficiency alone, in which case the windowsills and other trim can remain in place (which, ultimately, will save you money). As long as you're replacing a window of the same size, you can keep your old frame - all you have to do is pull out the old window sashes and insert the replacement window into the old frame. If you can't save your trim, consider upgrading to a deeper windowsill or a wider apron beneath it to add a touch of elegance to your room. Remember to use a high-grade glossy paint on windowsills (and any other trim that may be exposed to moisture and mold) to prevent these elements from entering and rotting the wood.
If changing your windows is part of a larger home improvement project, you should always change the windows before you paint the walls. If you're installing new siding on the exterior of your home, you'll want to fit it to the shape of the new windows.