This is a question a get from everyone of my clients during a home inspection. My answer depends on what I see during the home inspection.

If I see original wood or metal windows, with either rope or chain counter balances my answer is yes. These windows are always drafty, rarely work and are usually poorly maintained. The truth about windows is that a single paned window, that is a window with only one sheet of glass has an insulation value of R1. A double paned window has a rating of R2, A triple glazed a rating a R3. The gas filled windows, which are very expensive and quickly give up their gas, rate about an R4.

R ratings determine how slowly a material will allow heat to penetrate it. The higher the R value the better the insulation, i.e. less heat loss. So as you can see a window rate R3 is just 50% more efficient than a window rated R2. But compared to a typical wall which has an R11 to 19 rating, windows are the worst insulators in the home. If your old wood windows work, and the storms are intake, caulked and functional, replacing is a bad investment. Replacing with R2 windows won't reduce heat loss. Replacing with expensive R3-4 windows will take upwards of 10-15 years to break even. If your windows are not functional, don't lock, have broken storms are metal framed, damaged, etc., replacing is recommended. Again, the break even point here is 6-8 years. When shopping for vinyl windows, make sure you look at full size example. The miniature samples that sales people carry are not representative of the final product. Small examples will always be strong and sturdy, even if the vinyl extruded is poor. Thinly extruded vinyl windows will deform over time and are prone to seal failure, which allows moisture in between the panes of glass. Over time this leads to a cloudy appearance. Ask for references and check them out! Replacing windows can add cosmetic value to the home, reduce maintenance and energy costs. The homeowner should take these into account when considering a window upgrade. Be wary of contractors who want a large deposit up front. most window replacements are done in two days, and usually do not require a permit, so long as the window sizes stay the same. Always check with the town construction official first.