I am often asked if a few degrees in temperature really affects the total energy usage for the home. The answer to this question is yes. Here is how critical the setting and accuracy of your thermostat is:
Thermostat Setting
A few degrees in temperature does make a significant difference in total energy used by the home heating and cooling system. Let’s take winter as an example. The heat loss through outside walls, ceilings, and floors is directly proportional to the difference in temperature between inside and outside temperatures.
If we take a typical winter month for average outside temperature and average inside temperature we have the following example: Outside of 45F and inside of 70F versus outside of 45F and inside of 73F.
70-45=25 and 73-45=28, then 28/25=1.12 or twelve percent more energy used with a three degree rise in inside average temperature. This example gets even more drastic at moderate outside temperatures say of 60 degrees. 70-60=10 and 73-60=13, then 13/10=1.3 or thirty percent more energy. This more moderate example would apply to most summer temperatures as well.
Thermostat Accuracy
I use a very reliable thermometer that I check for accuracy periodically. I first put the thermometer in ice water (32F) and take the reading and then into boiling water to take a reading (boiling water temperature varies with altitude, at sea level 212F, at 900 ft about 210F, and at 3000 ft about 206F or about 1 degree for every five hundred feet). This tells me if the thermometer is off at its end points as well as the relationship over the range of the scale.
It is not unusual to find thermostats in homes with as much as plus/minus five degrees. This could mean a huge difference in both energy usage and comfort in the home.
It is always a good idea to check the accuracy of your thermostat by simply using a calibrated kitchen thermometer (you can use the method described above) to check the accuracy of your thermostat. This should be done when moving into a new home or when installing a new thermostat. If you find your thermostat with an offset versus the calibrated thermometer, then you should adjust your thermostat accordingly. - Mark
Thermostat Setting
A few degrees in temperature does make a significant difference in total energy used by the home heating and cooling system. Let’s take winter as an example. The heat loss through outside walls, ceilings, and floors is directly proportional to the difference in temperature between inside and outside temperatures.
If we take a typical winter month for average outside temperature and average inside temperature we have the following example: Outside of 45F and inside of 70F versus outside of 45F and inside of 73F.
70-45=25 and 73-45=28, then 28/25=1.12 or twelve percent more energy used with a three degree rise in inside average temperature. This example gets even more drastic at moderate outside temperatures say of 60 degrees. 70-60=10 and 73-60=13, then 13/10=1.3 or thirty percent more energy. This more moderate example would apply to most summer temperatures as well.
Thermostat Accuracy
I use a very reliable thermometer that I check for accuracy periodically. I first put the thermometer in ice water (32F) and take the reading and then into boiling water to take a reading (boiling water temperature varies with altitude, at sea level 212F, at 900 ft about 210F, and at 3000 ft about 206F or about 1 degree for every five hundred feet). This tells me if the thermometer is off at its end points as well as the relationship over the range of the scale.
It is not unusual to find thermostats in homes with as much as plus/minus five degrees. This could mean a huge difference in both energy usage and comfort in the home.
It is always a good idea to check the accuracy of your thermostat by simply using a calibrated kitchen thermometer (you can use the method described above) to check the accuracy of your thermostat. This should be done when moving into a new home or when installing a new thermostat. If you find your thermostat with an offset versus the calibrated thermometer, then you should adjust your thermostat accordingly. - Mark
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