Posted By ICFHybrid on 28 Mar 2013 01:30 AM
BTW, the biologist in me feels compelled to note that badgers are a member of the Mustelid family along with minks, otters and weasels. While they are not rodents, they do include them in their diet.

ICFH - indeed you are correct. One of the fur bearing group. Since its his mind we want and not his pelt, I guess he's save for now ;-))

Of course, we haven't seen his pelt, have we? ;-]

What I really want to know is why is the "Parker's Spring 2013 Collection of New Arrivals" displaying in the ad space for me?

Posted By KevinC on 24 Mar 2013 11:47 AM
I've been working on my plans to build in Minnesota - 55020.

What do I need to know about ventilation before I talk to the next guy?

Back to the OP original question...a good start to learning about ventilation would be Paul Raymer’s “Residential Ventilation Handbook: Ventilation to Improve Indoor Air Quality”.  It is starting to get dated, but it certainly explains ventilation basics including point-of-source, ERVs, HRVs, and make up air.

 

…and if you are from MN, you definitely need to find that wily Badger

Good article. Accurate monitoring/control of humidity levels and good (HEPA?) particulate filters are probably far more important than some fixed outdoor air ventilation rate.

The GBA article is a good one - but a bit discouraging in that it shows that we're all really "flying by the seat of our pants". Since intuition seems to be the guiding factor, mine tells me that low level (50 to 150 CFM) 24/7 ventilation is probably pretty ineffective in actually providing clean air in a home. I can't help but think, again intuitively, that there will be pockets of stagnant air that never get changed. Who will put in an elaborate duct system to distribute 100CFM? I suspect that without a distribution system the exhaust and supply will simply short circuit. My analogy would be trying to replace a bucketful of dirty water with clean water by trying to take out a few drops each minute and adding a few drops of clean water each minute. My gut tells me you'll never get there - especially with constant sources of pollution happening concurrently. The article stresses controlling the source of the pollution and that makes huge sense to me. I advocate for the periodic whole house purge. Pick a breezy day and open all the doors and windows for about 10 minutes a few times a week. Yes it's an energy hit but everything is a trade off. With some thermal mass in a house the hit shouldn't be much more than the heat (latent and sensible) contained in the air volume purged. As an additional musing - I wonder if air quality has been studied relative to submarine design. I would imagine it would be pretty important as opening the windows is frowned upon there!

low level (50 to 150 CFM) 24/7 ventilation is probably pretty ineffective in actually providing clean air in a home.

My conclusion was the opposite - that low CFM ventilation is probably more than enough for adequately clean air. Issues with radon, moisture or new homes might be exceptions. If you have something that is releasing dangerous gases, eliminating it will be far more effective than ANY level of ventilation.

"controlling the source of the pollution and that makes huge sense to me"
Exactly. this house I've just completed uses electric (minisplit) heat and has an HRV running 24/7, so the potential sources of pollution are minimized. The tightness (.8ACH50) and the insulation values (5 (windows)/20/30/40/60 minimize the heat loss. Its a winning combination and can be done with a variety of materials and designs.

Who will put in an elaborate duct system to distribute 100CFM?

ERV/HRV ducting doesn't need to be elaborate.

My analogy would be trying to replace a bucketful of dirty water with clean water by trying to take out a few drops each minute and adding a few drops of clean water each minute.

If it's a ten liter bucket and you assume that a few drops are 1/2 milliliter, then you are talking about 30 ml/hr with a time to fill bucket of 333 hrs. At 100 CFM, you are going to replace all the air in an average home (say, 20,000 ft3) in about 3 hours, not to mention infiltration.

If you have ever played around with particulate "smoke", you will note that it is nearly impossible to get "stagnant air". Almost any disturbance, thermal or mechanical, will put it in motion. The trick in designing an air exchange system is to work with the natural air flow in a home.

Posted By Bob I on 30 Mar 2013 10:46 AM
"controlling the source of the pollution and that makes huge sense to me"
Exactly. this house I've just completed uses electric (minisplit) heat and has an HRV running 24/7, so the potential sources of pollution are minimized. The tightness (.8ACH50) and the insulation values (5 (windows)/20/30/40/60 minimize the heat loss. Its a winning combination and can be done with a variety of materials and designs.

Bob - isn't Martin inferring that 24/7 is over ventilating?

I totally agree with limiting indoor pollutants as the low hang fruit of the clean air. However I think the Canadian Codes have it right. The builder must install balanced tempered ventilation up to set rates (ashrae) but its up to the home owner how they use it.

I believe the best approach is one that uses all methods of clean air approach:
* A dedicated HRV/ERV duct system with exhaust air being taken out of the bathrooms and kitchen area.
* Good house plants that are known to provide natural air filtration and good O2 levels
* Opening windows when the weather allows for it
* A good HEPA filter for the home
* Reducing any VOC's within the home and using natural cleaning products if possible (Baking Soda works great)

Each home design will have its own specific needs but for my design I will run the ERV/HRV on a timer/programmer. Here in the desert SW during summer one can close up the house during the daytime heat and at night get fresh cool air into the home. The reverse during winter, limit venting at night and utilize more during the day when the air is warmer. Again, each home will be different based on location, design and occupancy levels.

Some things are not debatable; one of which is that building poorly sealed & leaky homes is a dumb idea whose time has come and gone.

For several years I left it up to the homeowner - I was installing controls to run a bathroom fan for extended periods to provide fresh air. I found later that most people turn it off and forget or neglect to turn it back on, meaning they were getting no fresh air. With tighter houses this starts to become dangerous. When we commission the house we test the ventilation rate and adjust the damper on the HRV to compensate. The danger of "too much" ventilation is simply increased heating cost so minimizing the heat loss by building a proper envelope covers that possibility. As for the homeowner, they can install a control that adjusts the time period from 24/7 to whatever, or they can unplug the unit.

no fresh air. With tighter houses this starts to become dangerous

Do you have more info on this? These people were getting sick? From what specifically?

from whatever contaminents are in their house. My first SIPS house in 1980 was for a couple who both smoked; six months later they told me they had been sick since they'd moved in. One gets used to contaminents in the air we breathe, but we aren't used to them at the concentrations that can build up in a tight house.

Yes, the idea of pulling contaminants from the source makes sense. As part of my design I'm going with dedicated ERV return venting, to pull pollutants directly from places like closets (think of the smells from outgassing shoes, purses, etc. in your walk in closet) the laundry room in a location to pull the fumes from the detergents, storage room, kitchen, pantree, etc. Then I'll pump air into the places where we spend time, bedrooms, family rooms, etc. I've also been trying to come up with ways to get air movement in places like corners, nooks and such. I've been thinking about maybe some small fans that would be on a periodic timer just to stir up that air once in a while so the ERM can pull it out. Dedicated exaust fans for baths, laundry (dryer), hood vent... So much to consider!!!

I've also been trying to come up with ways to get air movement in places like corners, nooks and such.

As ICFHYbrid pointed out, you will get air changes in these areas. Release some smoke into a room and notice how after a short time, the corners aren't clear.

As for the homeowner, they can install a control that adjusts the time period from 24/7 to whatever,

I was under the impression that recent energy code specified how the ventilation was to be controlled, thereby ensuring that it ran a certain minimum amount of time. IECC 2009? 2012? Did I dream it up?

Am I wrong, or is this Daikin system both HVAC and ERV? http://www.daikin.com/global_ac/products/residential/urusara_series/outline.html
I am building a SCIP home with three basic modules of space. Each module will have scip envelopes. The left module is two bedrooms with Jack & Jill baths and closets in between, with a total of about 720 sq feet. The right module is about 720 square feet of master bedroom & bath and spare bedroom/den and bath. The middle module is a big square with about 1280 sq feet of open space. It will contain my kitchen, eating area and living area. Could I not use the Urusara for heat/air and erv for the big middle module? And then perhaps use the Panasonic whisper comfort erv for the J&J bathroom fan and the master bedroom fan. The only room not connected in some way to ventilation would be the guest bedroom (where no one will sleep most nights).

What do y'all think?

It does appear as if that Daikin product has some sort of a media wheel capable of transferring moisture. You'd have to look up the product literature to see what kind of operations are recommended.

Your guest bedroom would still need some sort of ventilation. You wouldn't want to suffocate guests, even if it is only a few nights.

Are you trying to avoid putting in an entire HRV system?

Yes, I am trying to avoid any ductwork at all.