Does anyone know a way of calculating the amount of heating I need to maintain an average temperature in terms of kWh of heating per 24 hours? Ideally one taking into account weather conditions.
I have a pretty big Home Assistant setup which includes switches for individually controlling all the (electric) heaters in my home. I’m also using an electricity supplier that changes the amount they charge every 30 minutes to reflect supply and demand. Given these rates are published at least 24 hours in advance I can currently choose a number of hours to run the heaters per day and have an automation automatically select the cheapest periods. I’m paying less per kWh for heating than I would if I was using a gas boiler. Plus, it’s all from renewables, so working out that number of hours is the next step.
If you’re measuring the temperature in the room currently, you could try trending it yourself. Start the heater, and see how quickly the temperature rises (e.g., degrees per hour). Call this Rate 1.
Then turn off the heat and see how quickly the temperature drops. Call this Rate 2. For the formula below, make it a positive number.
Assuming the weather conditions are similar and the room temperature doesn’t change too much during data collection:
Rate of heat loss = Heater power * Rate 2 / (Rate 1 + Rate 2)
This number could be impacted by the weather: temperature, wind and insolation (affected by time of day, time of year, latitude, and cloud cover). It’s also impacted by room conditions (temperature, slade position, how many times the door is opened), so you’d need to do a few trials to get a sense for thr impact of different variables.
You’ve probably already thought of this, but your strategy is going to result in noticeable swings in temperature in the room, because ypure going to do a lot of heating at once when prices are cheap, then turn off the heating and let the room cool. Compare that to a thermostat that tries to maintain a constant temperature.
Sounds like a fun project - good luck! I’d love to hear updates here as you go.
We’re thinking along the same lines, I think, I just wanted to see if someone smarter than me had published their solution :D
I’ll post if/when I get something that works, thanks.