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There's really no reason to keep your house as warm, when you are not there or are sleeping. With a smart thermostat, you can set how your week looks. When you are at work, always out Thursday night, when you go to bed and get up again,,etc. That way you can save energy when you are not home or do not need it.
If you have a geothermal heat pump, or air to water. Much energy can be saved by being able to lower the flow temperature on the pump. This can be done by having large radiator. A large radiator can heat the same room with less temperature water.