The Smart Thermostat

Heating, ventilation and cooling is the largest source of residential energy consumption.

We demonstrate and implement how to use cheap and simple sensing technology to automatically sense occupancy and sleep patterns in a home, and how to use these patterns to save energy by automatically turning off the home’s heating, ventilation and cooling systems. We call this approach the smart thermostat.

Smart thermostats are devices used for becoming more efficient in domestic energy usage.

They can contribute to more economic energy use in two ways.

On the one hand, they can control the heating system in an effective manner, for example by not heating the house if the detect that nobody is at home.

But on the other hand, they can play an important role in making the persons in the house aware of the severity of their energy usage; so, that they are encouraged to change their behavior or their house into a more sustainable environment.

Through the use of artificial intelligence, the thermostat can make some homeowners aware, for example, that there is room for improvement in insulating a particular section of the house.

We will give the thermostat the intelligence it needs to analyze what are the energetic characteristics of the house. This could provide the basis for comparisons with other users and recommend specific advises about measures to reduce energy usage.

Studies have shown that 20-30% of heating, ventilation and cooling energy could be saved by turning off those systems when residents are sleeping or away.

These savings, however, have been difficult to realize: typical residents will not manually adjust the thermostat several times a day, and programmable thermostats are too difficult for most people to use effectively. In fact, recent studies have found that households with programmable thermostats actually have higher energy consumption on average than those with manual controls because users program them incorrectly or disable them altogether.

Household appliances to be controlled by our energy management system are: water heater, air conditioning unit, clothes dryer, and other electric machines.

Each can have a comfort setting from the owner, for instance, the minimum temperature for water in the water heater can be set to 45ºC, the comfortable base temperature for air conditioning unit can be 23ºC (±1.5ºC), and job completion time can be specified for clothes dryer, and any other machines.

A homeowner can also set their priority, i.e., residents may choose the water heater to be more necessary than the air conditioning unit and may have similar priority order for the other appliances.

The energy management algorithm starts by gathering current state information about all appliances, output limit and duration and customer priority and preferences. It then constantly checks for demand limit violations and comfort setting deviations. Efficiency limit violations are prevented by cutting OFF power to less important appliances as defined by the user.

Comfort setting violations are prevented by turning ON appliances (in order of rank) keeping total consumption under a specified productivity limit. This way, the algorithm learns to meet both the efficiency limit requirement and the homeowner’s comfort preference setting.