If I add a single ventilation tube and put a fan in it, blowing air inside, this could deter air from leaking in through the usual gaps (such as under baseboards) and bringing chemical odors with it.
I believe that with all the weatherstripping in place (I still haven't added door weatherstripping, which I bought last week; also I still haven't finished sealing the A/C unit either) the room will be VERY WELL SEALED. That is the benefit of having sealed the entire building with 1.5 inches of polyurethane closed cell foam, combined with 4 inches of open cell foam, combined with rigourously sealing all the gaps around electrical boxes, etc.
With this very well sealed room, it might only take a trickle of incoming air to keep the room pressurized, preventing chemical smell sources from draining inside the room, and forcing them to drain outside.
That was my latest idea, anyway. For that matter, if the air being forced in (through clean stainless steel ventilation tube) is sufficient, it will positively ventilate the room, forcing out air through the usual gaps, as well as preventing any additional air from coming in through those gaps. That would be "normal positive ventilation." So that possibility is #2.
The third possibility is to have two ventilation tubes. With two separate tubes, it's harder to arrange positive ventilation (both tubes would have to have working fans) but you can have several flavors of passive, assisted passive, and other types of ventilation as well as positive and negative ventilation. A full on passive system with crossflow could provide very good ventilation at the cost of energy loss. But the tubes could both have reversible fans, and closeable doors on both side, so that many ventilation options are possible, and if the doors can be closed at the right times, relatively little energy loss.
Back before I was considering A/C, I though of the idea of having two ventilation tubes mounted at near ceiling height. That was also consistent with the idea of having solar power and sealed storage batteries, as even the best sealed batteries might leak H2 under some circumstances. Regular storage batteries need lots of ventilation and would be better housed in a separate highly open structure. Anyway, that is why I already have sealed stainless steel ventilation tubes.
With an air conditioned structure, it's not so good to have ventilation to keep cost down, ventilation will bring in hot air during the summer and even bring heat through the pipe itself. At least that was what I thought, and why the current design has no ventilation system other than the doors and window (which work VERY WELL, by the way, when the building can be left open, because the crossflow ventilation is excellent.)
Anyway, my original idea was to have both tubes on the north side but near east and west corners, thus capturing ventilation from the normally SE windflow.
But clearly the maximum air pressure occurs on the east side, and a tube added at ceiling height near the SE corner would do the best job of capturing that. Such a tube might not even need a fan, it would work simply on typical outside wind pressures. A fully passive design could be realized with an oversized horn-like intake. I like the idea of having both a fan and a damper door. The tube should be mounted so the outside register is mostly in the shade so as not to conduct summer heat inside.
It's not clear whether this would work better than an inside-only VOC filtration system. The filtration system would contribute a small amount of heat, 60 watts or so, operating constantly at it's lowest speed. That is nothing compared with the 1000 watts or so of heat an outside ventilation tube might bring in on a hot day. So I think the air filter is actually a better idea from the standpoint of energy conservation. But the question is how well the filter actually works. I know that a sufficient amount of ventilation from outside works. But there also, I don't know how much ventilation would be required. And also, I don't know how much energy "loss" (including unwanted heat gain that needs to be air conditioned away) would be created by any particular ventilation strategy.
So for now, it seems like going ahead with plan to cure building in the summer sun this summer, then add a VOC filter in the fall, is still the best start. Only if there is still a problem after filter is added should ventilation options be explored.
Another option might be to replace the A/C with a new Friedrich Chill model that has an integrated selectable exhaust vent (I think that works on negative ventilation, therefore negative pressure). But I've already got a brand new A/C, actually the XStar that I have is more expensive than the Chill units, I wonder if the one I already have is actually better made. And positive pressure, provided by an auxiliary ventilation system, might work better.
*****
Standing under ceiling fan was where I got the strongest smell of chemicals (after french doors had been open a few hours). Funny, over in the room corners underneath the shelves I didn't smell anything. This made me wonder if smell isn't coming from the floor itself, from the flexbond and poly grout which are still curing. Or possibly from the ceiling, which picked up smells but has never been cleaned.
I believe that with all the weatherstripping in place (I still haven't added door weatherstripping, which I bought last week; also I still haven't finished sealing the A/C unit either) the room will be VERY WELL SEALED. That is the benefit of having sealed the entire building with 1.5 inches of polyurethane closed cell foam, combined with 4 inches of open cell foam, combined with rigourously sealing all the gaps around electrical boxes, etc.
With this very well sealed room, it might only take a trickle of incoming air to keep the room pressurized, preventing chemical smell sources from draining inside the room, and forcing them to drain outside.
That was my latest idea, anyway. For that matter, if the air being forced in (through clean stainless steel ventilation tube) is sufficient, it will positively ventilate the room, forcing out air through the usual gaps, as well as preventing any additional air from coming in through those gaps. That would be "normal positive ventilation." So that possibility is #2.
The third possibility is to have two ventilation tubes. With two separate tubes, it's harder to arrange positive ventilation (both tubes would have to have working fans) but you can have several flavors of passive, assisted passive, and other types of ventilation as well as positive and negative ventilation. A full on passive system with crossflow could provide very good ventilation at the cost of energy loss. But the tubes could both have reversible fans, and closeable doors on both side, so that many ventilation options are possible, and if the doors can be closed at the right times, relatively little energy loss.
Back before I was considering A/C, I though of the idea of having two ventilation tubes mounted at near ceiling height. That was also consistent with the idea of having solar power and sealed storage batteries, as even the best sealed batteries might leak H2 under some circumstances. Regular storage batteries need lots of ventilation and would be better housed in a separate highly open structure. Anyway, that is why I already have sealed stainless steel ventilation tubes.
With an air conditioned structure, it's not so good to have ventilation to keep cost down, ventilation will bring in hot air during the summer and even bring heat through the pipe itself. At least that was what I thought, and why the current design has no ventilation system other than the doors and window (which work VERY WELL, by the way, when the building can be left open, because the crossflow ventilation is excellent.)
Anyway, my original idea was to have both tubes on the north side but near east and west corners, thus capturing ventilation from the normally SE windflow.
But clearly the maximum air pressure occurs on the east side, and a tube added at ceiling height near the SE corner would do the best job of capturing that. Such a tube might not even need a fan, it would work simply on typical outside wind pressures. A fully passive design could be realized with an oversized horn-like intake. I like the idea of having both a fan and a damper door. The tube should be mounted so the outside register is mostly in the shade so as not to conduct summer heat inside.
It's not clear whether this would work better than an inside-only VOC filtration system. The filtration system would contribute a small amount of heat, 60 watts or so, operating constantly at it's lowest speed. That is nothing compared with the 1000 watts or so of heat an outside ventilation tube might bring in on a hot day. So I think the air filter is actually a better idea from the standpoint of energy conservation. But the question is how well the filter actually works. I know that a sufficient amount of ventilation from outside works. But there also, I don't know how much ventilation would be required. And also, I don't know how much energy "loss" (including unwanted heat gain that needs to be air conditioned away) would be created by any particular ventilation strategy.
So for now, it seems like going ahead with plan to cure building in the summer sun this summer, then add a VOC filter in the fall, is still the best start. Only if there is still a problem after filter is added should ventilation options be explored.
Another option might be to replace the A/C with a new Friedrich Chill model that has an integrated selectable exhaust vent (I think that works on negative ventilation, therefore negative pressure). But I've already got a brand new A/C, actually the XStar that I have is more expensive than the Chill units, I wonder if the one I already have is actually better made. And positive pressure, provided by an auxiliary ventilation system, might work better.
*****
Standing under ceiling fan was where I got the strongest smell of chemicals (after french doors had been open a few hours). Funny, over in the room corners underneath the shelves I didn't smell anything. This made me wonder if smell isn't coming from the floor itself, from the flexbond and poly grout which are still curing. Or possibly from the ceiling, which picked up smells but has never been cleaned.
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