[Greenbuilding] Passive Ventilation for Tight Houses
corwyn at midcoast.com
Tue Feb 17 12:37:25 CST 2009
Eli Talking wrote:
> I want to consider how we provide passive ventilation to a tight home.
> I am ok with using electricity to organize heat to reduce overall
> energy use and create comfort. However, we must consider power
> outages. Also, we may consider normal operating ventilation without
> electricity for those that aspire to live off the grid. Yes, we can
> run on solar electricity and the funky batteries that are in towe.
> However, please consider non electirc ventilation. All grid connected
> houses experience power outages. With the grid as cobbled together as
> it is, I expect more. As we design buildings for safety, comfort and
> efficiency, we should plan for these outages so that it is not a crisis.
Passive ventilation has problems in that it is not consistent. You get
more when the wind blows, for example.
Running an HRV on off-grid electricity is not a big deal, just make sure
it is in your power need calculations. There are good ones which draw
low current. Are there any that run on DC? I don't know, but even that
should be be too hard a retrofit.
For a house which is normally on the grid, during a blackout,
ventilation is probably not the biggest issue. Around here we get power
outages mostly in the winter. Anyone staying in their house therefore
has to heat it first. Most heat sources are going to need air. A
non-powered HRV is still an air intake (possibly two).
> To those aware of the need for air the obvious response to power
> outage in a tight house in the winter is to open a window. Can we
> really count on people to do this? Can we calibrate how much window
> needs to be open?
Probably; people are designed to detect stale air . And probably not.
> To compel our occupants of tight buildings to vent, could be have the
> dampers set to open when the electricity goes off?
Compelling rarely works. If I had something like that in my home and
didn't understand the ventilation needs, I would plug it, especially
during a power outage when I would want to conserve heat. If I DID
understand the ventilation needs, compelling is unnecessary.
> More generally I am interested in a discussion of how to achieve
> passive ventilation in deliberately tight homes.
I have been trying to work out a design for a cheap thermsiphon solar
heated air intake system. Or possibly with solar PV fan assist. I
would welcome thoughts.
Thank You Kindly,
Green Fret Consulting
Kermit didn't know the half of it...
topher at greenfret.com
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