Energy efficient homes (was: Energy demand is the problem)
From: ehrbar (ehrbargreenhouse.economics.utah.edu)
Date: Fri, 15 Jul 2011 16:18:36 -0700 (PDT)
Sharon Villines wrote:

> We have two fresh air ducts on our HVAC system for the
> large dining room and kitchen of our commonhouse. The
> dampers were always open but we only needed that much
> fresh air when the room was fully occupied. We asked the
> HVAC engineer to wire the dampers and put a switch
> upstairs so we could open the dampers when we were
> expecting a large crowd but otherwise not be heating and
> cooling outdoor air.

I am not an expert but here is my experience from recent
remodeling.  Old gas furnaces are constructed in such a way
that they cannot function without allowing large amounts of
energy to escape through the flue.  It seems modern furnaces
are much better (they need PVC or stainless steel flues
because of condensation water).  Just closing the flue is
against code for a good reason; the combustion gases from
Natural gas are of course much better than oil or coal but
still have very nasty stuff in them, not the least of which
is PM2.5 (ultra-fine particulate matter).  This is also an
issue with gas stoves.  Install vents which do not
recirculate but go outside and have a powerful fan.  300 CPM
(cubic feet per minute) is too little.  I found some with
440 CPM in the store I was looking, that's what I picked.
When I heard about the health dangers of gas stoves (which
of course nobody wants to tell you because profits are at
stake), I wanted to replace it with an electric induction
stove, but didn't have the required 220 volts in my home.


Another energy saving measure which seems obvious but has
its drawbacks is tightening up the building, i.e., plugging
all the little holes through which air can get through the
walls.  If the building is too tight, then the outgassing of
carpets and paints etc in the building will be a health
hazard.  Solution: tighten the building and at the same time
install a heat recovery ventilator (in arid regions as in
SLC) or an energy recovery ventilator when moisture is an
issue.

All this is much easier with new buildings than as
retrofits.  If I were member of a cohousing group building
now I would insist on following the passive house standards.
They are stricter and more relevant than LEED.  It
increases the original building costs by 15% or so, but I
think this will pay off tenfold over the life of the
building in energy savings, comfort, and resale value.
Finding an architect who is familiar may be the biggest
hurdle, but consciousness about this is increasing rapidly.

Hans

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