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This is a very interesting thread.<br>
<br>
I had never considered things from John's point of view regarding
the other - and often more complex - machinery/systems in a typical
home versus the ventilation equipment. Having been a long-time
off-grid, fridgeless neo-hippy, I understand the aversion to
equating machinery with sustaining life. At the same time, I've
never questioned the need for my car to be fed as much air as it
requires to operate... So thanks for that kick in the perspective,
John.<br>
<br>
(As a sidebar... I've often wondered why our ventilation equipment
isn't coupled with our refrigerators. Use those heating coils on the
back of the fridge to heat incoming air in the winter. Run the
ventilation every time the fridge cycles... fridge should perform
better if the coils cool down more...)<br>
<br>
I still have questions (actually, it was the initial question that
kickstarted this discussion) about <i>how much</i> ventilation is
required. I still feel that our code requirements are overkill, as
they are designed for homes with greater need to move moisture and
toxins out of the building. Seems to me that the ventilation
requirements began from a need to exhaust first, and the fresh air
component was a side-effect of needing to exhaust without
depressurizing, not to ensure oxygen for occupants.<br>
<br>
How much of this discussion is really about occupants having enough
oxygen? To what degree are we really in danger of asphyxiation
inside a tight home? Just to get inside the home, we open up the
door and create a bunch of exchange... In a home with no combustion
devices inside, do people really asphyxiate or even get sick from
excessive CO2? What amount of trickling fresh air would service a
bedroom adequately?<br>
<br>
Obviously I'm not really looking for hard answers here... it's all
highly specific to location, insulation, air tightness, heating
equipment, etc. I'm just musing on where my own next steps will go
in order to make tight buildings with adequate ventilation. My
search for answers to "how much" is in pursuit of designing systems
that can potentially be run with as little energy as possible in
order to be as resilient as possible. I guess I'm going down the
same path with ventilation as Passivhaus does with heating
systems... trying to make the needs as low as possible and meet them
in the least energy intensive way.<br>
<br>
Where do the numbers the codes use come from? And are there ways to
calculate and propose our own numbers based on actual needs for
oxygen and for exhaust? And if you're a person who answers yes to
this, do you want to talk more off-list?<br>
<br>
Thanks all, this group is the best brain trust I can imagine.<br>
<br>
Chris<br>
<pre class="moz-signature" cols="72">--
Chris Magwood
Director, Endeavour Centre
<a class="moz-txt-link-abbreviated" href="http://www.endeavourcentre.org">www.endeavourcentre.org</a></pre>
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