Q. My single pane windows are not in bad condition, but they waste a lot of energy and are hard to clean. How can I improve their efficiency without investing in entirely new thermal replacement windows? — W.E.

A. There are several ways to improve the efficiency of your windows without a huge investment in all new replacement windows. These methods not only lower your heating and air-conditioning costs, but they reduce dust and outdoor noise inside your home and the fading of your furniture and curtains.

One excellent replacement window alternative is to install new do-it-yourself tilt-in replacement sash kits in your existing window frames. The tilt-in feature allows you to clean the windows from indoors. Installing these kits costs less than half as much as new replacement windows. You can install one yourself in less than an hour.

There are many glass options available, including super-efficient argon gas-filled low-E glass and tinted glass for hot climates. Filling the gap between the panes of glass with argon gas increases the efficiency and reduces outdoor noise. The sash frame is made of wood with options of aluminum cladding.

If only the channels in your window frames are worn so that the sash is loose and leaky, you can buy inexpensive do-it-yourself replacement frame channels. One type of replacement channel is designed so you can easily remove the entire window sash from indoors for cleaning.

If your window sash won’t stay open in the summer and keeps sliding down, you can install another design of airtight replacement channel. In addition to stopping air leaks, the channels create a snug spring-friction fit to allow your windows to slide up easily, yet stay open.

Applying new do-it-yourself insulating window film saves energy and greatly reduces the sun’s fading rays on your furniture. This film has a special low-E coating on it, similar to the new super-high-efficiency window glass. Window film is very easy to install yourself.

There are several film options. You can install nearly-clear window film which you can’t even tell is on your windows. This reduces heat loss in the winter and heat gain in the summer. For greater heat reduction in the summer, you can apply a tinted low-E film. You may choose to use a clear film on east and north windows and a tinted film of south and west windows.

You can write to me for Utility Bills Update 122 listing addresses and telephone numbers of manufacturers of high-efficiency replacement tilt-in window sash kits, frame channels, and insulating window film, a sample piece of insulating window film, and product information and specifications. Please include $1.50 and a self-addressed business-size envelope. Send to James Dulley, 6906 Royalgreen Drive, Cincinnati, Ohio, 45244.

Q. I am concerned about global warming from using too much energy and inefficient products. About how much carbon dioxide (CO2) gas is produced from various types of energy we use? — N.M.

A. You will be surprised at how much CO2 gas is produced. Each kilowatt-hour (KWH) of electricity you use produces from 2.14 to 2.37 pounds of CO2 gas depending on whether oil or coal generation is used. One KWH is the amount of electricity used by one 100-watt light bulb in just 10 hours.

Based on the usable energy output, burning natural gas produces the least amount of CO2 gas. For one million Btus of energy, natural gas produces 118 pounds of CO2 gas compared to 694 pounds from coal-generated electricity.

James Dulley studied energy management at the doctoral level at Harvard.