I live in a 2 story semi detached house that is heated by a single stage NG forced air furnace. I have the Ecobee 3 Lite installed in my home. It is on the main floor. I have a digital thermometer that I have in my bedroom. There seems to be a 1 degree Celsius difference between the main floor and the upstairs with the upstairs being cooler. Now before you tell me that I need more insulation in my attic. I need to inform you that my home inspector when I bought the house that there is about 40 inches of blown in and batten fiberglass insulation. The house is almost 50 years old. Could the wall insulation have settled enough that it is causing it to be cooler? Other thoughts?