Quote:
Originally Posted by MN Renovator
5ACH naturally infiltrated would chill a house in the winter really quick and if you changed the air out 5 times per hour your furnace would be a huge monster and I couldn't imagine the energy bills. You'd feel the air moving constantly and the comfort would be terrible because of it.
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This is exactly the situation that many millions of homes experience right now.
BTW, you might be interested to see this ASHRAE table:
Quote:
Originally Posted by MN Renovator
0.35ACH of ventilation either through forced ventilation or infiltration is quite a lot of air to move.
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You might be speaking out of opinion rather than direct experience here. 0.35 ACH is actually quite difficult to achieve. I've been working on my house a long time now, and I'm not even close.
There was a previous post on ER, about some guy who was trying to get his house Passive House certified, and was not able to get it down beyond 0.6 ACH as I recall.
To achieve 0.35 ACH pretty much means starting before the house is built and planning in infiltration prevention measures from the very beginning.
In Europe, there is a big Passive House retrofit initiative going on and with energy costing 2X what ours costs, and all the years of Passive House practice under their belts, they have come to realize that the best retrofit efforts can only hope to achieve 0.65 ACH.
MN Renovator, if you actually had a blower door test done on your house, you might get some useful information.
The 0.35 ACH figure was from earlier Passive House work. The early efforts had gotten infiltration down to below 0.35 ACH and occupants were expressing displeasure with the houses because they felt so stuffy.
The fix was to shoot for 0.35 ACH, or less if possible, and then to supply 0.35 through HRV, with the input air flow balanced with the output air flow so as to not exacerbate the inevitable infiltration.
I have seen photos of German HRVs and they are about as large as a full-size cook stove.
In a discussion with the guy who currently heads up the Passive House initiative, he was asked about ventilation in general and HRV in particular, and how important were they.
His response was that a Passive House should start with a HRV.
BTW, those who are interested in this discussion should read the thread on
DIY HRV is is a storehouse of great information.
Best,
-AC