Garage Heating

Graph from yesterday's home temperature measurements:

Of particular note are the garage (dark blue) and attic (green) traces. There are three bumps in the graphs that mirror each other and are co-incident; these events are when the garage door opened to let a car in or me out to shovel snow. The two areas are connected by an access hatch that I tend to leave open, allowing air to flow between them easily.  During these bumps in the graph, the garage temperature falls and the attic temperature rises.  The warm air that has formed in the garage is displaced into the attic by the cold air moving in through the open door.  When the door closes, the temperatures in both places begin moving back to their former state.

This leads me to to observations:

1. The air flow through the garage is not very large when all the doors are closed.  The space is far from air-tight but it must be tight enough because the garage warms back up once the doors close.  The cold air from the outside isn't getting in near as well.  And where is that heat that is warming the garage coming from....
2. The insulation between the living space and the garage could be better. The heated house is the only source of energy that could be warming the garage after the door closes.  This has implications for the summer; keeping the garage cool by opening doors and allowing air to flow will hel reduce the cooling demand in the living space.