I have a programmable thermostat that is, well, dumb. It is willing to set times and abide by those, but it doesn't take in to account the weather. What I'm looking for is a smart thermostat that can learn my behavior and also make decisions based on the humidity inside the house and the temperature outside.
NEST and other smart thermostats seem to be able to predict temperature but not more advanced analytics. Does anyone know a thermostat that can move with the weather? Especially for sudden warm or cold fronts, it makes sense to set thermostat based on temperature and not hours of the day. We generally keep our thermostat warmer in the summer due to the wide difference between RH and temperature inside and out. 80 feels so much cooler on a hot summer day than in a late spring heat wave.
Ideally it would be a thermostat that can raise the setpoint with the outside temperature (say 15degrees trailing, max 85 degrees) throughout the day and also based on relative humidity (say 60%). Then, as the day cools down, lower the setpoint based on the outside temperature and the relative humidity (Leading 15 degrees with a floor at 72, 40%RH). This way I could minimize the deltaT while keeping my house relatively dry.
There are three settings on the Nest. Heat Only == Cool Only == Heat Cool. I have several customers on the H/C setting during these shoulder seasons. It does that. Not as sophisticated as your description above. Effective, yes.
The best equipment for doing this "communicating" equipment. I'm most familiar with Carrier Infinity series, but American Standard and Goodman offer similar control I believe.
Infinity can manage airflow and staging. This allows it to adjust focus from removing sensible to removing latent. If you really want air conditioning to have that "doesn't feel like air conditioning, just feels comfortable" outcome, you need to go this direction.
Some Inverter Driven Mini-Splits can operate using the same principals.
Ted, Without using name brands or proprietary terms, how would you suggest specifying 'communicating equipment'?
Very easy to spec 'Builder's Grade' 80 AFUE, single speed draft induced gas fired furnace with 13 SEER AC. Or Upgrade to 90+ AFUE sealed combustion with 15 SEER or Upgrade 2 to 94+ sealed combustion with 16+ SEER AC. and so on.
I could use an Upgrade Level III in my arsenal.
That is stretching me a fair distance outside my expertise. Let me convey the idea, then you can design to it:
Imagine you have a milk jug with a few holes in it. You want to keep it 1/2 full of water and place it under a tap. Your design strategy is to keep it as close to 1/2 full without ever shutting the tap off. Shut the tap off and you get a big penalty. Turn the tap on like a fire hose, you get a big penalty.
The water is proxy for thermal comfort and fresh air. A modulating boiler outdoor reset on steroids.
So your thermostat needs to know how to manage the throttle on a LOT of things. BTU management AND adjusting airflow, and in the really sweet equipment, compressor adjusts and exv adjusts refrigerant efficiency.
NOW we have to design so airflow stays above .08 and below .4-.5 if you really want optimal distribution, distribution cost, and even comfort. Too high, costly and noisy. Rare occasion too low, trickling/uneven distribution. So we test ESP on existing equipment and hope we can bring that typically terrible number into line when we drastically down size the replacement.
Since you are constantly and cheaply (fans laws) mixing air, why not inject fresh, latent managed air into that btu circulation? Sure, why not? http://bit.ly/VentDehum
All temps stay in line - Latent/Sensible/Mean Radiant. Super efficient. Super comfortable.
Comfort - http://bit.ly/comfortcalculator
Super Efficient - http://bit.ly/rickchitwood
Hope that helps. Let me know if it looks like Greek instead of English...
Some of the higher end Emerson thermostats do this. It's called "cool savings" and adjusts the setpoint automatically based on system run time. The more the system runs, the greater the offset.