Thermal decision table...

[Externet]

Hi.

Stuck with mental farts on how to make a graphical decision chart, for using thermal switches.  Suggestions please ?  Perhaps someone lucid  has done it ?

Attic temperature can vary  -20C to +50C  along the year.

Exterior ambient temperature can vary -20C to +40C along the year.

Desired temperature in dwelling 15C to 25C , outside that range, energizing HVAC system is allowed.

Bidirectional fans located at boundaries attic/living area ;  living area/exterior.

Thermometers/thermostats located in the three locations (attic, exterior, living area) to command fans for the correct air flow direction to avoid energizing HVAC.

 

Example :  If exterior ambient is 10C;  attic air is 22C,  living area is 12C, energize fan flow from attic towards living quarters and no action from fan between exterior-to-living.

There will be many variables along the day, time, season and weather to affect the decisions, and the limits when to stop fanning.