This applet simulates what happens inside your house when the temperature and dew point change outside. You have control over the outdoor values by sliding the red colored portion of the two thermometers (one for temperature and one for dew point). The Relative Humidity meter will instantly tell you the value for the outside.
As you change the values outside, your indoor environment is slower to
change. (We run this simulation at several times normal speed...)
In the winter, you probably would set the furnace to go ON when the temperature inside falls below the Thermostat setting. In the summer, you may set the air conditioner to go ON when the indoor temperature rises above the Thermostat setting.
And of course...Have Fun