I might not be using the proper terminology but in commercial applications roof top units, RTUs, normally include an economizer.  Is there an equivalent for residential applications?  Maybe in combination with a DOAS?

It's called a window :-).

DOAS is a good match for radiant cooling - not common in residential. Would also be useful if you had a need for dehumidification and ventilation without any heating/cooling.

Really how do those work



I guess I was hoping that there was an automated system out there. In my area, zone 6, during the cooling season the outdoor temperature often drops below the set point overnight. It seems silly that the AC continues to cycle over night when it could simple exchange outside air. As part of a automated solution I would want to have some means of controlling the indoor humidity, either by treating the incoming air or a whole house system. In fact, with a more advanced control system, if the outdoor temp would allow if you could let the indoor temp fall several degrees below the set point to get a jump start on the next day.



Maybe the gains aren't worth the effort? Based on how you describe a DOAS, aside from the radiant cooling, it seems to fit what I would envision with the addition of some logic controls.

I agree, there should be an automated whole house ventilation system capable of significant CFM. Thermal mass works a lot better if you manage the temperatures/humidity by closing and opening windows, but figuring out when and doing it twice a day (or even again in the middle of the night as the house gets too cold) gets old.

Economizers can be installed on a residential system. The use of an enthalpy control would be preferred. There are several companies that mfg such a product.

Your right, if you dig around a bit you can find a few different companies offering solutions.  I'm just a bit surprised that there aren't more offerings.  Maybe economics of it don't work out?  In theory the exchange system would still need a dehumidifier.  To cool the house on exchanged air I'm thinking the economizing system would log twice as much run time as the AC system would if you weren't exchanging.  Maybe in that case you're back to the same place with total power usage. 

Also my experiences are based on older haphazardly insulated homes.  Maybe this isn't as much of an issue with a tight properly insulated (where I'm hoping to get to) home? 

It is not practical in most wet climates.

We use an ERV in most applications where four seasons are distinct.

If you are not in a dry climate and you have cold weather, open window--or powered economizer--will make IAQ harder to control.

Tight home, sealed combustion, HRV or ERV and central de-humidification if required.

It looks like California is requiring whole house fans or "central fan systems" in many areas. Might as well fully automate it to optimize thermal mass and "free" heating/cooling benefits without significantly impacting comfort or hassle.

Agreed, as homes get tighter and better insulated, it costs less to just seal them up and always use the standard HVAC system to keep them comfortable. On the other hand, it's irritating to see the AC running at 7pm when it's comfortable outside.