DEAR TIM: My husband and I bought a house filled with old windows. These are the type that slide up and down with the old cast-iron weights. They are in great shape, and don’t seem to leak much air. Should we replace these old wood windows, or is our money better spent on other things? If we decide to remodel and upgrade, is it hard replacing old windows? Funds are limited, and we must get the biggest bang for our buck. Stacy T., Dunkirk, NY

DEAR STACY: One thing’s for sure. If you don’t replace the old windows, you’ll probably end up having to repair those old windows from time to time. If you do, be aware that there is a very high likelihood that lead will be in any paint or even clear varnish on them. Be sure to discover all the sinister dangers of lead, and how even small amounts of lead dust can cause great harm to you, your husband or any children or pets you have.

Old home windows are possibly the largest energy thieves in your home. Single-pane glass has an R-value of only 1, and typically there is no insulation between the window jamb and the rough framing of the window. The concealed space where the cast-iron weights go up and down absolutely has no insulation. Poor or non-existent caulking around windows can allow massive amounts of air infiltration. In other words, if you decide to keep your old double-hung windows, you need to understand you’ll be wasting energy dollars whenever your furnace or air conditioner is operating.

Old windows can be found in thousands of places, even newer homes! PHOTO CREDIT: Tim Carter

To make an informed decision about investing in new windows, you need to put a pencil to paper. There are many things you need to consider, including current heating and cooling costs, projected maintenance of the existing windows and future price increases on fuels that you use to heat and cool. It’s not easy to do all of this math, and that’s why many people cave in replacing their windows hoping they save money. Well, in some instances the people never save any money at all. Always remember that you never begin saving money until such time as you have recaptured the money you spent on the improvement plus any and all interest that money could have generated in your savings account.

Get copies of the utility bills for the past two years for this home. You can often separate the heating cost by looking at the bills for the summer vs. the winter. If the fuel source is natural gas or propane, you can see the dramatic rise between fall and spring. Do the math to calculate the approximate cost of heating the home. You may be surprised to discover that the cost is less than $1,500 per heating season if this is a smaller home.

Let’s assume that even with new windows installed you could save as much as 30 percent. I’m not saying you will, but let’s make that assumption. This means that you’ll only reduce your heating cost per year by $450.00. For now, let’s assume the cost of the fuel will rise 4 percent per year. This means that in ten years, you would save approximately $5,397.00. That’s not bad, but imagine if you had spent $10,000 or more replacing the old windows with new ones! It would take another eight or nine years of energy savings just to break even, not counting the lost interest on the money. If you finance the new windows, the payback period is even longer because of the interest you pay on the loan.

Tax credits, rebates and incentives from utility companies and other programs can impact the payback period. All of these need to be considered. But beware of fast-talking salespeople who promise you instant savings. That’s simply not the case.

If you decide to try to save money and install the windows yourself, it can be a challenge. There are replacement kits that allow you to install new windows that match your existing ones in the current openings. With practice, you could completely replace a window in about an hour, maybe 90 minutes. You’ll need a few tools to do this and possibly a belt sander in case you need to scribe a window to a jamb that’s not square.

It’s very hard to make accurate cost-savings projections. There are some highly scientific methods that take into account the higher R-value of the new windows and lower air-infiltration rates, but thermostat settings, heating-degree days of the winter from year to year, interior thermostat settings, etc. all come into play.

Perhaps the best thing to do is to take a hard look at the efficiency of your existing furnace and air conditioner. If you have an old furnace that eats too much fuel, you may get a faster payback by using your money on a high-efficiency furnace and air conditioner. Once again, you must do the math and see when you actually recapture the money you spend. If you do this, then be sure to seal all air leaks around your old windows.

If you live in an area where heating with wood is allowed, you may look into this alternative. There are some very efficient wood stoves that produce vast amounts of heat. If you have access to wood at a low cost, perhaps your best bet is to invest in a decorative, yet functional, wood stove. As you can see, there are many things to consider.