Greenhouse
Looking at the graph (and trying to keep my fingers from freezing):
I noticed interesting thing – the temperatures in my office tend to go down a bit every day (look at those last four green peaks). Keep in mind that my thermostat is set to the same temperature as it was before, yet those temps really go down. Looking for explanation I tried to remember what changes in weather did we observed during those last 4 days. Did it become colder outside? Not really. Maybe hotter? Naa… Rained? Snowed? Was it windy? And then it strike me – we got more and more sun each day. So apparently upper level of our house acts as greenhouse absorbing energy from sun. And because the thermostat is in fact mounted there, lover level rooms, not exposed to radiation heat became colder and colder.
One additional reason why giving those rooms more decision power as when to turn the furnace on is not that bad idea.
