For many households living in large older homes reducing the amount of living space that needs to be heated during the winter can be an important way to reduce heating costs. In theory, if you reduce the amount of living space that is heated to one half the total space you could reduce heating costs by one half. In practice the savings are not as high as that because there are still heat losses from the heated area to the unheated area. But the savings can be considerable.

You can also lower the thermostat in rooms that are used only for sleeping or are used infrequently enough that a lower temperature would not inconvenience or harm household members.

What you can do:

Identify what rooms might not be needed at all during the heating season, or used only for a several week period during the heating season. If possible select rooms for sealing off that are on the north or west side of the house, or that have the most “leaky” windows or are generally considered to be the coldest rooms in the house.

CAUTION: Do not select rooms that have water pipes running through exterior walls. The risk of water pipes freezing and bursting is too high in severely cold weather.

For rooms you plan to use infrequently: Close vents or turn down thermostats in rooms that are only used infrequently or for sleeping.

For rooms that you are going to seal off: Add some sort of window covering to all windows to reduce heat loss (a colder room will result in more heat loss from the main part of the house).

Close vents or turn down thermostats.

If you have the time adding insulation or blankets to the room’s interior walls (the walls that are shared with the main, heated area of the house) will cut down on heat loss from the heated area of the house to the unheated room.

Seal off doors using weatherstripping and rope caulk.

Savings:

It is difficult to be precise or even offer a good estimate of energy or cost savings because there are so many variables involved (how cool you keep the rest of your home, how leaky your home is, how leaky the room that you are sealing off is relative to the rest of the house, how good a job you do of sealing off the room). However a conservative estimate of heating energy savings would be that for every 10% reduction in total heating space you can expect to save 2% on your heating costs.