Where did you read this? We have done testing with University of Idaho on economizers for a couple years, our findings would not suggest that as a parameter. Sensor and intake location are key items, but each structure can have some idiosyncrasies. The proper sizing of the intake is also an issue which needs careful attention.
I can't find it now, but it was on a website like buildingscience.com or another one. The discussion was for a humid climate (that's me) so I was worried maybe having the intake hood on the north side would cause more issues with buildup in the duct or something along those lines. The thread didn't mention the reason behind it.
Thanks for the link. I am not sure of the design and the execution of the fresh air intake that she is advocating and the location being low enough for the homeowner to change a filter just does not fit the best practices we arrived at. We had some gable penetrations and some through the roof. Gable is better, but can be more difficult to accomplish. The damper system must shut down the intake completely, once the system starts, you don't want to degrade the efficiency of the system. The question that we have variance on from participants is the humidity question, some are much more willing to have a higher humidity understanding they are both saving energy and breathing fresh air. We also continue to operate the fan on constant mode therefore we utilize whatever filtration is in place in the system already. Northern exposures give you more time before the temperature of the area is degraded by the sun. This is also the reason a gable is better than and roof penetration. The issue with being lower to the ground is that you do end up with the potential for issues with false humidity sensor readings. If you are under the gutter, that is not draining, problems can occur. We logged some changes in humidity just from lawn sprinklers. Again, I think the issue of determining the operating parameters for your locale is the key. Some homeowners in the study we worked on had aesthetic reasons they wanted the intake on another side of the home rather than the north. Those locations consistently showed less savings for electricity usage. The savings numbers can be significant.
In my case I want it on the north facing gable (for visibility, best air quality and no roof penetration) but was concerned about the comment about the north side. As far as filtering, mine would be an inline filter (Fantech FB6) in the attic next to the attic entrance (easy access) with an insect screen on the intake hood.
If you have not seen the CoolMizer we developed a couple years ago and the unit that Idaho Power & Light used in their pilot program let me know, I can send you a tech sheet and also a copy of the summary from the study when it is released.
An economizer in my location isn't really practical. There are maybe a total of 20 days out of the whole year where the outside air doesn't need some sort of conditioning. My purpose for the outside air is to improve ventilation.
I see no reason given for the non-north facing walls though.
In the south, where you are cooling dominant, I would WANT it north.
Which side of the house see's the least sun? North.
Second, you can't put a filter on an air inlet termination.
Said filter can be somewhere in the house, but not on the termination.
So having the termination accessible to the homeowner is useless. Which leads me to further doubt the north facing.
"Better tell the sandman to stay away, because we're gonna be workin on this one all night."
"Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."