The nights are getting colder, and you're thinking about lighting a cozy fire. Read the information below before you strike that match. Although you might be thinking about using your fireplace to cut down on your heating bills, many fireplaces can actually remove more heat from a house than they produce. According to the U.S. Department of Energy, a typical vertical-back fireplace with an open front is at best 10 percent efficient in converting fuel to energy and delivering it to a room. The rest of your fuel dollars escape up the chimney. Fireplaces pull cold air into the house from small gaps around windows and doors. Also, most fireplaces are inappropriately situated on exterior walls. The large mass of masonry that makes up most fireplaces are poor thermal insulators and readily conduct room heat to the outdoors in cold weather. One simple and very inexpensive tip is to use flue sealers. Even brand-new dampers may not close tightly or become warped after the first hot fire. They may even be installed incorrectly. You can use inflatable draft stoppers that you insert into the flue and inflate when not using your fireplace. The web site states that a less expensive solution is to use an old foam rubber seat cushion or pillow: Place it in a heavy plastic bag, and insert this into the flue. Be careful with this, though-attach a long red tail to it to remind you it's there so you remove it before building a fire. Wood-burning appliances and fireplaces also may emit large quantities of air pollutants that can jeopardize health. Wood smoke contains hundreds of chemical compounds, including nitrogen oxides, carbon monoxide, organic gases, and particulates. Carbon monoxide is a poisonous gas that has no color and no odor. It replaces oxygen in the blood, leading to suffocation and probable death. The U.S. Centers for Disease Control and Prevention states that particles released from fuels that are not completely burned can irritate or damage lung tissue. These pollutants attach to microscopic particles that are inhaled and carried deep into the lungs, where they are lodged, causing extensive damage. Particles from combustion as well as other airborne particles can cause or contribute to asthma and restrictive airway diseases. Try out the new Java-Log made from recycled coffee grounds. Voted one of Time magazine's Coolest Inventions of 2003, the logs burn up to three hours, save trees, and have a faint, sweet aroma rather than the chemical smell associated with most manufactured logs. According to testing from Omni Consulting Service, the logs have significantly fewer emissions than firewood-96 percent less residue after combustion, 85 percent less carbon monoxide, 86 percent less creosote deposits, and 31 percent less particulate matter