A thermostat is a controller that maintains a system’s temperature near a fixed point. The simplest thermostat does this by switching a heater or AC on and off to maintain the desired temperature (known as the bang-bang control). I spent a couple of days adding thermostats to Energy2D and developing a simple GUI for setting up thermostats.

In Energy2D, a thermostat is a connection between a power source and a thermometer. A thermometer can be linked to any number of power sources, but a power resource can only be linked to one thermometer. In the property window of a thermometer, the user can select the power sources it will control.

This Energy2D model demonstrates how a thermostat works. Turn on the temperature graph. Let the simulation run for a few cycles and then turn on the sunlight. Compare the behavior of the temperature graph. You can also try to move the temperature sensor around to examine how the on/off time of the thermostat depends on its location.

You should discover from this simulation that, when the sun shines on the house, it ends up using less energy to maintain the inside temperature because the time that the heater is on is shorter (see the differences of the two graphs in the first two images of this post). You should also find out why we should not put the sensor of a thermostat near a window.

The third image shows multiple thermostats at work to create different heating zones. This Energy2D simulation has four heaters in three rooms, each of which is controlled by a thermostat. 

From these demos of thermostats in Energy2D, you can see the richness of the software. I will add more useful features like this to make Energy2D even better. Stay tuned!