FR/Question: cost based heating

Checklist

[X] I have filled out the template to the best of my ability.
[X] This only contains 1 feature request (if you have multiple feature requests, open one feature request for each feature request).
[X] This issue is not a duplicate feature request of previous feature requests.

Is your feature request related to a problem? Please describe.

Hi, I’m considering to use this nice project to group multiple heating solutions. In my house I have both central heating with zone control that uses gas, and inverter based airco’s that can efficiently heat electrical. Cost of gas vs Electra is a criteria to determine which heaters to use (airco’s or central).

Describe the solution you'd like

My feature request is to support external helpers to define a preference for a particular heater in the HVAC group. I think evaluating criteria like cost and/or weather conditions should be kept apart from this HVAC group. Those criteria can become rather complex by themselves (e.g the efficiency of heating with airco’s depends heavily on the outside temperature…). The HVAC group can simply use Boolean helpers to select the preferred heater

Describe alternatives you've considered

Own scripts and automations

tetele / hvac_group