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> Houses are not that airtight. Long before a house gets airtight enough to maintain a pressure differential efficiently, the occupants will get ill as off-gass

> Houses are not that airtight. Long before a house gets airtight enough to maintain a pressure differential efficiently, the occupants will get ill as off-gassing from carpets and paints and wood finishes cannot escape. They are that airtight. That is why they put in mechanical ventilation such as HRV and ERV. The houses are that air tight that off-gassing is a problem once they get down below 0.6 ACH @ 50 pascals as they do in passive house builds. > If you run a large negative pressure in a typical house, you also risk carbon monoxide poisoning from sucking exhaust from the furnace into the living space. It happens, I read this the other week. https://www.reddit.com/r/TinyHouses/comments/5ec33i/the_big_tiny_house_problem_nobody_seems_to_be/ https://www.reddit.com/r/TinyHouses/comments/5ec33i/the_big_... > They use air pressure this way specifically because construction is not airtight. If you run a negative pressure differential (which requires a pretty beefy blower to accomplish and isn't very energy efficient), you end up pulling air in from all the gaps and cracks and porous materials, which means that contaminated air is not going into all the gaps and cracks and porous materials. I understand why a negative pressure room works. The linked to Wikipedia page explains it. They are an example of manipulating air pressure to affect an outcome. What I don't understand is what point you're trying to make. If it is that the air tightness of a house coupled with a HRV is not sufficient to effect barometric pressure on a human body, then I already acknowledged that might be so. It also might be sufficient, which is why suggested getting an expert's opinion.

dpark 10y ago
> They are that airtight. That is why they put in mechanical ventilation such as HRV and ERV. The houses are that air tight that off-gassing is a problem once they get down below 0.6 ACH @ 50 pascals as they do in passive house builds. Yes, off-gassing is a problem. Off-gassing is a problem long before a house is really airtight enough to efficiently maintain a pressure differential, though. 0.6ACH@50Pa means that your house is extremely airtight by even modern standards. It also means that a very light pressure is sufficient to cause your house to completely exchange it's interior air in less than two hours. If you want to depressurize a house enough to offset a high pressure weather system, you're going to be moving a lot of air. > It happens, I read this the other week. Yes, I know it happens. That's why I said it. This is another reason that you cannot significantly depressurize a house. Plus your door would fly open and break your face when you turned the knob. > What I don't understand is what point you're trying to make. > If it is that the air tightness of a house coupled with a HRV is not sufficient to effect barometric pressure on a human body, then I already acknowledged that might be so. It also might be sufficient, which is why suggested getting an expert's opinion. Yes, I'm saying it won't work. For many reasons. You don't need an expert. It doesn't even pass the sniff test.

dpark 10y ago

> They are that airtight. That is why they put in mechanical ventilation such as HRV and ERV. The houses are that air tight that off-gassing is a problem once they get down below 0.6 ACH @ 50 pascals as they do in passive house builds. Yes, off-gassing is a problem. Off-gassing is a problem long before a house is really airtight enough to efficiently maintain a pressure differential, though. 0.6ACH@50Pa means that your house is extremely airtight by even modern standards. It also means that a very light pressure is sufficient to cause your house to completely exchange it's interior air in less than two hours. If you want to depressurize a house enough to offset a high pressure weather system, you're going to be moving a lot of air. > It happens, I read this the other week. Yes, I know it happens. That's why I said it. This is another reason that you cannot significantly depressurize a house. Plus your door would fly open and break your face when you turned the knob. > What I don't understand is what point you're trying to make. > If it is that the air tightness of a house coupled with a HRV is not sufficient to effect barometric pressure on a human body, then I already acknowledged that might be so. It also might be sufficient, which is why suggested getting an expert's opinion. Yes, I'm saying it won't work. For many reasons. You don't need an expert. It doesn't even pass the sniff test.