When to open windows to cool or warm a building

My uninsulated apartment building went from too cold to too hot in about a week, which is normal in Canberra. People have started to open the windows in the stairwell in addition to their apartment windows. The timing of the opening seems a bit misguided – people open the windows in the morning. During daytime, the air outside is warmer than the air inside the stairwell, but during the night the outside air is colder. To state the obvious: to cool down the building, open the windows for the night and close them for the day. Currently the opposite seems to happen, although I counter this trend by closing the windows in the morning when I notice them open.
In general, if you want the building cooler and the outside air is colder than the inside, then open the windows, but if the outside is warmer, then close them. If you want the building warmer and the outside air is colder than the inside, then close the windows, but if the outside is warmer, then open them. This could easily be automated with temperature sensors outside and inside the building connected to a thermostat and small electric motors opening and closing the windows. Such a system would save some of the heating and cooling costs of the building.
There may be non-temperature reasons to open and close the windows, for example to let smell out of the stairwell or to keep insects from coming in. The second reason is not relevant for my building, because all windows have bugscreens and the exterior doors have a gap an inch wide under them, which the insects can easily use to get in.

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