Monitoring House Temps

​My house is fairly new so it should be insulated to at least recent building code standards. I was still concerned about the how much heat was getting transferred from the attic to the house. 

So I plotted temperature of the house versus temperature of the attic. I would open all the windows late in the evening and would pull in cooler temperatures using box fans. Then in the morning, I would shut all the windows up and monitor how quickly the heat transferred from the attic into the home.

I have 3 temperature probes in the attic space that were initially added for monitoring lineset temperatures for my HVAC unit. I placed the other two sensors in the laundry room on the second floor. My objective was just a room without any windows that was somewhat near the center of the house - I'm not as interested in the thermal resistance of the walls but instead focused on the thermal resistance from the ceiling->attic.

It does appear to transfer at a pretty slow rate, especially considering there is a ΔT≈70°F