In addition to the fuel a heating system uses, several characteristics of a home and its heating system influence how much energy is required to stay warm during cold weather. These include the local climate, the home's building envelope, the efficiency of the heating system, thermostat settings, and the size and layout of the home.
Where you live has a major influence on how much heat your home needs. Homes in colder climates need heating for more months of the year, and their heating systems must work harder on the coldest days to keep indoor temperatures comfortable. Homes in milder climates may only need heating for a few weeks each winter.
Heat naturally moves from warmer areas toward cooler areas. The colder it is outside, the faster heat escapes from a home, and the more energy the heating system must use to replace it.
A home's building envelope is the physical barrier separating the heated interior from the outdoors. It includes the roof, walls, floors, windows, and doors.
During cold weather, heat escapes through the building envelope in two main ways. First, heat moves directly through walls, ceilings, windows, and floors. Insulation slows this heat transfer. Second, warm indoor air leaks out through gaps and cracks around windows, doors, outlets, attic hatches, and other openings, while cold outdoor air leaks in.
A well-insulated and air-sealed home loses heat more slowly, so it requires less energy to stay warm than a poorly insulated or leaky home.
Different heating systems require different amounts of energy to provide the same amount of heat. More efficient systems deliver more heat for each unit of energy they use, resulting in lower operating costs.
Maintenance also matters. Dirty filters, blocked vents, and equipment that has not been serviced can make a heating system work harder and use more energy.
How heat is delivered throughout the home can also affect efficiency. For systems that use ducts, warm air can escape through leaky ducts or lose heat as it passes through cold attics, garages, crawl spaces, or other unheated areas. As a result, some of the energy used to heat the air may be lost before it ever reaches the living space.
The thermostat setpoint is the indoor temperature the heating system tries to maintain. During cold weather, higher thermostat settings require the heating system to run more often and for longer periods of time.
The greater the difference between the indoor and outdoor temperature, the faster heat escapes from the home. Lowering the thermostat setpoint, even by a few degrees, can therefore reduce heating demand and energy costs.
Larger homes generally require more energy to heat because there is more space to keep warm and more exterior surface area for heat to escape through.
A home's layout also plays a role. High ceilings allow warm air to rise away from occupants, and rooms located above unheated garages or crawl spaces tend to lose more heat through the floor. Homes that share walls with neighbors, such as apartments and townhouses, typically need less heating because shared walls are exposed to heated spaces rather than cold outdoor air.