Comparing outside to inside temp

Configuration
1

I’m trying to get notified when the outside drops below inside temp on a summer night. If this happens, then I can cool the house by opening windows and not using AC. And the opposite for winter.

Of course it’s not that simple.

  • Not every day is hot to begin with
  • It could be a dip due to rain, and once it clears we’d want windows closed again
  • spring/fall days vary a lot, and each other day could be heating vs cooling
  • which room should I compare?
  • useless if no wind - I’ve had 6deg difference and no wind = no change in house temp after an hour

Should I wait for it to drop a few deg, or for a time frame? I also have a sensor for “Today’s Maximum Temperature” that may be useful.
I got this as the simplest state so far. What tips do you have to make this actually useful?

alias: Outside Temp Drop
description: ""
trigger:
  - platform: numeric_state
    entity_id: sensor.home_temp
    below: sensor.living_room_temperature
condition: []
action:
  - service: script.announce
    data:
      message: Outside temperature dropping
      speakers:
        - media_player.speaker
mode: single
2

I compare inside and outside enthalpy (it’s a measure of energy content of the air and includes humidity). It’s extra helpful if you’re jumping between AC and windows, as it helps ensure you don’t make things worse (say it’s cool but raining/very humid).

3

I used to* do something similar. Rather than trying to have HA keep track of all the variables I just used the AC coming on as the trigger to check whether it was cooler outside than in. Should be pretty simple to add other conditions like wind speed greater than X, humidity < Y, pollen count < Z, etc. If it is raining out then you can just ignore the announcement.

  • I say used to because the family got tired of google yelling at them to open the windows.
4

How do I get these into my system?
I have the weather svc to give me outside humidity, sensors for temp/humidity in each room.
Hope it’s not too hard !

5

The Thermal Comfort integration calculates them, so it’s pretty easy. I actually calculate them myself, because this is a recent addition to that integration (and I prefer English units which it doesn’t output for that value).

As long as outside is less than inside, you won’t be making your AC work harder later on. Keep in mind these values don’t necessarily correlate to perceived temperature (so it could FEEL cooler outside, but actually be higher Enthalpy).

7

Thanks, I had no idea this existed. Now I created a sensor that I use to change my windows icon on my dashboard color of its better to be open. Except at night.

         {% set current_time = now().hour %}
         {% if 22 <= current_time or current_time < 6 %}
           off
         {% elif states('sensor.thermal_comfort_moist_air_enthalpy_inside')|float > states('sensor.thermal_comfort_moist_air_enthalpy_outside')|float %}
           on
         {% else %}
           off
         {% endif %}
       friendly_name: "Windows Decision"
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