Nice details as usual!
On a much smaller scale my Nuheat (single zone) in the kitchen is a relatively huge thermal mass: more than a third of the apartment square footage. It’s the primary heat source in the entire place. Adjusting it seems to be most effective when done manually and tweaking the programmed set points. Thinking about the reasons why that is:
- We bake quite a lot and use the (gas) oven.
- The kitchen has a seriously efficient hood exhaust that can close the kitchen door if cranked to high.
- When we do laundry with an unvented electric (evaporative) dryer the bathroom fan stays on and vents the humidity … and draws in, in an uncontrolled fashion, outside air.
How is your outside air intake? Seems like if you had a substantial HRV/ERV with HEPA/plasma filtration you could use the cooler overnights + thermal mass to cheat some watts/BTUs. In winter I like to sleep in a cold room like a Finnish baby and in general I find that people don’t realize how nice it is to open windows or suck the heat out of a bedroom. This has distinct disadvantages when you’re trying to heat your space during the day! In warmer or transitional seasons though this is advantageous. Zoned HVAC with the ability to heat and cool at the same time is ideal: you can use room air and thermal masses as batteries.
I have an iQAir HealthPro w/carbon filters that has 6 CFMs between 40 & 240. I just got the duct kit that will allow me to finally interface it to the outside (i.e. on the intake side). I’m pretending this is a “spring energy saving project” but it’s probably more about dust avoidance and it remains to be seen whether it will save any watts. Sense will definitely help to quantify things. My 5,500-ish cubic foot space is going to be running on positive pressure. Working out a practical method for HRV/ERV is one of those non-trivial tasks that means it may never happen. I wish there was a small HEPA ERV on the market that checked all my boxes.