I've got to admit that I'm the first to preach about increasing energy efficiency in our homes, but not the first to make it happen. The truth is: I'd love to replace every dated window in my home, but I can't afford it. I know there are tax credits and I'd love to cash in, but new windows are a major ticket item. So, I looked into buying do-it-yourself window film for my huge picture windows. In the summer, my house is like an oven with the heat they bring in. Wintertime means heat loss as the warm air seeps away. There are many options when it comes to film for existing windows...and just as many opinions about it. You can have industrial-grade window films professionally applied to existing glazing. The professional films block up to 99 percent of ultraviolet (UV) rays, saving furniture and rugs from fading while reducing heat buildup. This results in a huge savings on the cooling bills in the summer and maybe even the heating bills in the winter (it depends on the type of film you get). The 3M web site lists some products that are tax-deductible. Then you need to get an installer. Watch out for the warranty on your windows, though, as film applied can cause a heat buildup within the glass itself, resulting in seal failure. Some sites report that this generally occurs if the film is applied on the inside, so remember to install it on the exterior. The last set of debates centers on the cost of film versus replacement glass. When you calculate the cost of upgrading your UV and low-e protection, consider the tax credits, the longer life of your furnishings, the cost to purchase and the cost to install. If your warranty is voided on the original windows, be sure the window film company picks up the remainder of any warranty items so that you will have full coverage. If they will not, price out the cost of replacement glass with UV and low-e protection. If you're really on a budget and hope to replace the windows ASAP, go to the local home store and get do-it-yourself film. It may discolor down the road, but a season's protection from heat loss and heat buildup may be worth it.