There are many ways to provide supplemental heat to those cooler rooms in a home. You can use a fireplace if it happens to be in the room where the extra heat is needed. An electric space heater is an option if your space is relatively small or if you need something that will provide a greater amount of heat, you could use a kerosene heater. Each of these options are useful in certain situations, but one option that can be adapted to work in almost any situation is a gas fueled ventless heater.
A ventless heater can be turned on for just a few minutes to take the chill off in a room, or can be set on low to provide a steady flow of heat. Where a kerosene heater needs a steady circulation of air for ventilation, vent free heaters can be burned without a vent as long as the heater can draw air from other rooms of your home. Otherwise, do not place the heater in a confined space that is shut off from other parts of the house. If the heater does not have proper air circulation, carbon monoxide can build up and could result in death with prolonged exposure.
The modern versions of these vent-free heaters do come equipped with an ODS (oxygen depletion sensor) device that is designed to shut the unit off if the oxygen level near the burner drops below the proper levels. However, if you are using any type of gas burning device in your home it would be in your best interest to acquire and maintain a carbon monoxide detector for an additional safeguard.
You should also keep in mind that these devices are meant to be utilized as supplemental heat. While they can be used as a short term primary heat source in the event of a power outage or some other emergency, they should be shut off for a while every 5-6 hours to insure the prevention of a build up of carbon monoxide or excessive moisture.
Ventless heaters come in a variety of sizes and you should have no trouble locating one that will serve your needs no matter what size room you need to heat. By following a few well publicized safety precautions and having the unit installed and maintained by a qualified professional, your ventless heater should provide you with many years of safe and efficient operation and most of all, keep you warm and toasty regardless of how cold a punch Mother Nature chooses to deliver.